Homo-and heterobimetallic Pd-, Ag-, and Ni-hybrid salen-bis-NHC complexes

Article

pubs.acs.org/Organometallics

Homo- and Heterobimetallic Pd−, Ag−, and Ni−Hybrid Salen−Bis-

NHC Complexes

Melanie Mechler, Katja Latendorf, Wolfgang Frey, and Rene Peters*

́

Institut fur Organische Chemie, Universitat Stuttgart, Pfaﬀenwaldring 55, D-70569 Stuttgart, Germany

̈

S

* Supporting Information

ABSTRACT: salen ligands and N-heterocyclic carbenes

(NHC) are among the most abundant structural ligand motifs

for metal catalysis. In this article we present a modular

approach to chiral ligands merging both ligand motifs for the

preparation of bimetallic catalysts, in which one metal (M¹) is

coordinated by the salen moiety and the other metal (M²)

binds to two NHCs. After selective complexation of M¹= Pd^II,

Ni^IIion into the salen N₂O₂coordination site, heterobimetallic

M¹/Ag(I) complexes were synthesized which could be further

utilized for the preparation of homo- and heterobimetallic M¹/Pd^IIcomplexes by an oxidative transmetalation to Pd(0) as a key

step of the catalyst synthesis. The structures of the bimetallic complexes and the intermetallic distances strongly depend on the

counterions of M²= Pd^II, as revealed by X-ray and UV−vis studies. In the absence of an anionic ligand with suitable Lewis

basicity the salen oxygen atoms serve as bridging ligands for both metals. A preliminary investigation into catalysis showed that

the complexes are capable of catalyzing the 1,4-addition of oxindoles to 2-nitrostyrene.

INTRODUCTION

■

Bioinspired tailor-made catalysts, which similarly to enzymes

allow for a simultaneous activation of both substrates of a

chemical reaction by cooperation of two or more catalyst

functionalities, have recently been demonstrated to be highly

valuable for the asymmetric synthesis of chiral building blocks.¹

Among the diﬀerent dual-activation concepts investigated, the

cooperation of two metal centers, which is also well-known

from a number of dinuclear metalloenzymes,²constitutes a

particularly intruiging design principle for artiﬁcial catalysts that

oﬀers a great development potential.³

Figure 1. General modular design of dinuclear salen bis-NHC

complexes.

In this article we present a modular approach to scalemic

dinuclear Lewis acid catalysts merging the features of metal

salen⁴and NHC complexes,⁵two of the most abundant

structural motifs in homogeneous catalysts. The N₂O₂

coordination sphere of salen ligands can usually be used for

the complexation of hard and soft metal ions of diﬀerent

oxidation states.^4,6,7NHC ligands are also capable of binding to

a large variety of metals; however, with a considerably higher

binding aﬃnity to late transition metals.⁵

The general modular design of the catalysts presented herein

is depicted in Figure 1 and oﬀers a large degree of structural

and electronic variability by adaptation of (a) the metal center

M¹, (b) the metal center M²(both metal centers including

additional counterions/ligands where appropriate), (c) the

diamino backbone as the source of chirality, (d) the

substituents R on the phenolate part, and (e) the NHC donors.

steps with high overall yields (Table 1). N-Methyl-, N-phenyl-,

and N-mesitylimidazole and N-methylbenzimidazole were used

to synthesize imidazolium salts 3a−d.⁸Condensation of their

aldehyde moieties with (1R,2R)-1,2-diaminocyclohexane

(CyHex-H₄) and (R)-6,6′-dimethyl-[1,1′-biphenyl]-2,2′-di-

amine (BiPh-H₄) furnished salen ligands 4-CyHex and 4-

BiPh, respectively, in quantitative yields.

Synthesis of the Bimetallic Complexes. Selective

complexation of a Pd^IIor Ni^IIion into the salen N₂O₂

coordination site of 4 proceeded in quantitative yields with

Pd(OAc)₂and either NiCl₂in CH₂Cl₂at room temperature in

the presence of NaOAc as base (5-CyHex-Ni) or NiOAc (5-

BiPh-Ni) (Table 2). Complexes 5-M¹(M¹= Pd^II, Ni^II) were

then readily transformed into heterobimetallic M¹/Ag com-

plexes 6-M¹using 2 equiv of Ag₂O in 1,2-dichloroethane at 55

°C.⁹In contrast, bis-NHC complexation of M²= Pd^IIwith 5-

M¹to form 7-M¹under basic conditions was ineﬃcient, as a

RESULTS AND DISCUSSION

■

Ligand Synthesis. Bis-imidazolium salen ligands based on

the commercially available aldehyde 1 were prepared in three

Received: September 6, 2012

Published: December 18, 2012

112

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

Table 1. Three-Step Synthesis of Bis-Imidazolium Salen Ligands 4-CyHex and 4-BiPh

a

yield (%)

entry

3, 4

R¹

R²

R³

3

4-CyHex

4-BiPh

1

2

3

4

a

b

c

Me

Ph

H

88

87

73

93

>99

b

Mes

Me

d

C₄H₄

a

b

Yield of isolated product. Not prepared.

result of decomposition or formation of mono-NHC complexes

as major products. On the other hand, attempts to form 7-Pd

by oxidative addition¹⁰of the imidazolium N₂C−H bonds of 5-

M¹using a Pd⁰source gave no conversion at all.

Tris(dibenzylideneacetone)dipalladium (Pd₂(dba)₃, 0.6 equiv)

in CH₂Cl₂at room temperature gave access to 7-M¹in useful

yields (Table 2). ESI-mass spectra conﬁrm that the oxidation

state of M²= Pd is changed from 0 to +2 during the

transmetalation step. This stands in contrast to trans-

metalations of silver carbene complexes with Pd⁰sources

known in the literature, which generally proceeded with

retention of the oxidation state.^12,15Oxidation of the palladium

center is apparently a key factor in our system to drive this

transmetalation step and is caused by reduction of the silver

ions to form silver metal.

The positively charged bis-NHC silver complexes 6-M¹were

identiﬁed by ESI-MS but should be in equilibrium in solution

with neutral trimetallic bis-silver complexes 8-M¹, in which each

Ag^Iion binds to one NHC donor (Scheme 1). These latter

species could also be detected as minor species by high-

resolution ESI-MS for 8b-BiPh-Pd. This kind of equilibrium

has previously been reported in detail for other silver NHC

complexes.¹¹⁻¹³The extent of the corresponding ﬂuctuation of

the Ag−carbene complexes can often be estimated by the shape

and chemical shift of the ¹³C NMR signals of the carbene C

atoms.^11,12The signal of strong σ donors is shifted more

downﬁeld than the analogous signal of weaker donors.¹¹

Furthermore, silver NHC complexes that are static or have a

dynamic behavior which is slow on the NMR time scale often

show a ¹⁰⁷Ag/¹⁰⁹Ag−¹³C_carbenecoupling (doublet of a doublet).

As the dynamic behavior increases, the coupling pattern is

known to disappear and the C_carbeneresonance becomes broader

and eventually coalesces into a sharp singlet.^11,12In the case of

6-M¹broad singlets were found, pointing to an equilibration of

6-M¹and 8-M¹at a medium pace relative to the NMR time

scale.

The homobimetallic complexes 7-Pd are also available in a

single step from the ligands 4, as exempliﬁed for 7a-CyHex-Pd

(Scheme 2). Treatment of 4a-CyHex with PdCl₂(MeCN)₂and

K₂CO₃in DMF at 100 °C gave direct access to the bis-

palladium complex, albeit in signiﬁcantly lower yield than the

three-step silver carbene transmetalation route, as a conse-

quence of substantial decomposition. The oxidative trans-

metalation route via silver carbene complexes thus oﬀers the

advantage of milder reaction conditions.

1

As judged from their H NMR spectradepending on the

ligand backbonethe Ni complexes 5-Ni, 6-Ni, and 7-Ni are

either high-spin or low-spin complexes. Whereas the complexes

with a cyclohexane backbone are all diamagnetic, resulting in

sharp NMR signals, their biphenyl counterparts gave very broad

signals, pointing to a paramagnetic high-spin nature. Similar

eﬀects for Ni salen complexes have been reported before.¹⁶

The binding mode of 7a-CyHex-Ni was conﬁrmed by X-ray

single crystal structure analysis (Figure 2),¹⁷which identiﬁed

two diﬀerent rotamers in the solid state. The crystal structure

shows a pseudocentric behavior. There is also a possible

solution in P2₁/c, but with disordered positions around the

stereogenic centers of the cyclohexane moiety. For crystal-

lization attempts the almost enantiomerically pure substance

Ag−NHC complexes showing such a dynamic behavior are

often potent NHC transfer reagents.¹⁴For the formation of bis-

NHC−Pd^IIcomplexes transmetalation is normally achieved by

treatment with a Pd^IIsalt.^9,11In our case all attempts in this

direction failed, as a result of insuﬃcient reactivity, and in the

best case only traces of the targeted bimetallic complexes were

generated. However, the silver complexes 6-M¹could be

employed to prepare homo- and heterobimetallic complexes 7-

M¹with a palladium source in the oxidation state 0.

113

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

Table 2. Formation of Bimetallic Salen Bis-NHC Complexes

a

b

c

d

e

Yield of isolated product. Determined by ¹H NMR. Reaction done at 30 °C for 12 h. Reaction done at 35 °C for 24 h. The isomeric ratio could

1

not be determined by H NMR, since the product is paramagnetic.

was used. The substance was crystallized as a racemic twin with

a domain ratio of about 4:1. The Pd atoms display a slightly

distorted square planar coordination environment with a cis

orientation of the NHC moieties. The bite angles of the NHCs

are almost identical at 93.7(6) and 94.0(4)° for rotamers A

(top) and B (bottom), respectively. The Pd−carbene distances

for both complexes are notably diﬀerent. For rotamer A bond

lengths of 1.897(13) and 1.934(14) Å have been determined

that are signiﬁcantly shorter than for rotamer B with bond

lengths of 2.010(11) and 2.072(11) Å. This might point to less

conformational strain in rotamer A and thus a higher stability in

solution as well. We therefore suggest that the isomer of 7a-

CyHex-Ni formed in excess corresponds to rotamer A, whereas

the minor isomer is rotamer B (see Table 2). The angles

between the carbene ring planes and the corresponding metal

coordination planes vary over ranges of 64.8(5)−69.9(4)° and

64.7(4)−67.6(4)° for rotamers A and B, respectively. The

angles between the Ni and Pd square planes amount to 69.0(2)

and 60.8(2)° for rotamers A and B, respectively. The

intermetallic distances of the Ni and Pd centers are very

similar for both rotamers, at 6.169(2) Å for rotamer A and

6.134(2) Å for rotamer B.

114

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

Scheme 1. Proposed Equilibrium between Cationic Mono-Silver and Neutral Bis-Silver Complexes

Scheme 2. Direct Formation of the Homobimetallic Complex 7a-CyHex-Pd from the Ligand 4a-CyHex

Initial Problems by Imidazolium Counterion Ex-

change. In our initial synthetic studies the reaction sequence

presented in Tables 1 and 2 was performed via the bromo

analogue of 2.⁸However, upon formation of the Ag−carbene

complexes the bromide counterions were largely, but not

completely, exchanged with chloride, with a variation of the

bromide/chloride ratio from batch to batch. Halogen exchange

reactions upon the formation of silver NHC complexes in

CH₂Cl₂or ClCH₂CH₂Cl were ﬁrst reported by Danopoulos¹⁸

and soon thereafter by Lin,¹⁹while in many other cases no

halogen exchange was noted.¹²The mechanism of the halogen

exchange is not yet understood in detail, but the presence of

silver usually seems to be required for the known cases.

In the case reported herein, the presence of Ag₂O is not

essential, as control experiments have revealed. Stirring 5a-Pd

in DCE at 55 °C for 48 h in the absence of Ag₂O led to

quantitative halide exchange, as judged by ESI-MS, pointing to

a nucleophilic substitution at the solvent with ionic bromide.

The ligand 4a itself also promoted a counterion exchange. After

48 h under identical conditions ca. half of the bromide was

replaced with chloride. The presence of the palladium ion M¹

thus accelerates the nucleophilic substitution, most likely by

reversible solvent coordination.

To obtain bimetallic complexes with a deﬁned stoichiometry,

attempts were then made to avoid the counterion exchange.

Performing the Ag−carbene complexation in acetone at 55 °C

generated 10 in quantitative yield (Scheme 3). However, the

subsequent oxidative transmetalation gave the bis-Pd complex

11 with a signiﬁcantly lower yield of just 21% (with Cl⁻

counterions: 73%).²⁰

Chloride Exchange by Silver Salts. The two halide

ligands of Pd(II) in 7-CyHex-M¹or 7-BiPh-M¹can be

removed using diﬀerent silver salts AgX, such as silver acetate,

tosylate, and heptaﬂuorobutyrate (Table 3), forming 12-

CyHex-M¹-X or 12-BiPh-M¹-X, in each case as mixtures of

isomers (presumably again rotamers, vide supra). The single

species 13-CyHex-M¹-X or 13-BiPh-M¹-X are generated by

silver salts with “non”-coordinating anions X⁻such as triﬂate,

tetraﬂuoroborate, and hexaﬂuorophosphate (Table 3). In the

absence of an anionic ligand with a suitable Lewis basicity, the

salen oxygen atoms serve as bridging ligands.

Suitable crystals were obtained to determine the solid-state

structure of 13a-CyHex-Ni-PF₆by X-ray crystal structure

analysis (Figure 3), which conﬁrmed that the phenolate oxygen

atoms serve as bridges in an (ONiOPd) square, despite a

relatively strained O−Pd−O angle of 73.69(7)°.²¹Due to the

O bridges the intermetallic distance between the Ni and Pd

center is signiﬁcantly decreased to 3.0762(4) Å. Both metals

adopt a distorted-square-planar coordination geometry (sum of

the four bond angles at the corresponding metal: Ni,

362.88(9)°; Pd, 360.48(9)°), and the complex adopts a C₂

symmetric conformation in which one N-Me moiety of the

NHC donors points above whereas the other points below the

Pd square plane. This implicates that the chiral information of

both stereocenters of the diamine backbone is diastereo-

selectively transmitted into an element of axial chirality in the

NHC coordination sphere of M²(dihedral angles: O1−Pd−C−

N5, −132.7(3)°; O2−Pd−C−N4, 41.3(2)°) without the

formation of a second rotamer.

A very similar solid-state structure was also found for 13d-

CyHex-Ni-PF₆by X-ray crystal structure analysis (Figure 4).

Again the phenolate oxygen atoms serve as bridges in an

(ONiOPd) square with an O−Pd−O angle of 74.4(4)°

(intermetallic distance between the Ni and Pd: 3.057(3) Å).

Again, a nearly C₂symmetric conformation is found in which

one N-Me moiety of the NHC donors points above whereas

the other points below the Pd square plane (dihedral angles:

O1−Pd−C−N4, −125.4(14)°; O2−Pd−C−N5, 37.4(10)°).

Both structures appear to be highly strained, as the aromatic

substituents in positions ortho to the phenolate O atoms show

signiﬁcant deviations from coplanarity with the C−O bonds

and the aromatic rings. For 13a-CyHex-Ni-PF₆the deviations

115

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

of the carbon atoms of the benzylic CH₂groups from the

phenolate plane are 0.207(5) and 0.190(4) Å, respectively, and

the deviations of the C atoms of the CN groups are 0.364(4)

and 0.221(4) Å. For 13d-CyHex-Ni-PF₆the carbon atom of

one CH₂group deviates by 0.27(2) Å from the phenolate

plane, while the other shows coplanarity. The C atoms of the

CN substituents are located 0.21(2) and 0.11(2) Å out of

plane, respectively.

The complexation behavior of the mixed Ni−Pd complexes

is also visible: while the O-bridged Ni−Pd complexes 13 with

noncoordinating counterions BF₄, PF₆, and TfO⁻are bright

green, the corresponding complexes 12 with anionic donor

ligands coordinated to M²= Pd are either yellow, orange, or

red. The UV−vis spectrum (Figure 5) of the red 7a-CyHex-Ni

(red curve) bearing two coordinated chloride counterions is in

fact very similar to the spectra recorded for the orange 12a-

CyHex-Ni-OAc (black curve) and the yellow 12a-CyHex-Ni-

OTs (pink curve) with characteristic absorption maxima at

around 420 nm in each case. In contrast, the green 13a-CyHex-

Ni-BF₄(green curve) and 13a-CyHex-Ni-PF₆(blue curve) do

not have that absorption maximum but are very similar to each

other with characteristic maxima at around 315 and 370 nm.

Preliminary Results in Catalysis. As part of our program

to study cooperative eﬀects in asymmetric catalysis,^22,23we

have selected the 1,4-addition of oxindole 14 to 2-nitrostyrene

(15, see Table 4) for a preliminary investigation of the

bimetallic title complexes in catalysis.²⁴⁻²⁶For this reaction

type previous studies using bimetallic salen complexes

possessing one N₂O₂and one O₂O₂coodination site had

demonstrated a positive impact of two cooperating metal

centers on the stereoselectivity outcome.²⁷

−

In CH₂Cl₂at room temperature we found almost no

background reaction of oxindole 14 and nitrostyrene (15) after

20 h in the absence of a catalyst (Table 4, entry 1). Addition of

10 mol % of acetic acid had almost no eﬀect (entry 2). Diﬀerent

complexes of type 13-CyHex-Ni-PF₆carrying two imidazol-

ylidene ligands were then compared (entries 3, 7, and 9).²⁸

Using 5 mol % of these catalysts the product was usually

formed with low to moderate yields and moderate dia-

stereoselectivities. Unfortunately, each catalyst given in Table

4 provided only racemic product. Addition of acetic acid as a

cocatalyst to accelerate the protonolyis step of the putative

metal nitronate intermediate accelerated the reaction slightly

for catalyst 13b-CyHex-Ni-PF₆(entry 8) carrying N-Ph

substituents on the NHC moieties, while with 13a-CyHex-

Ni-PF₆(entry 4) and 13c-CyHex-Ni-PF₆(entry 10) the

conjugate addition was retarded by this change. With this

catalyst type possessing noncoordinating hexaﬂuorophoshate

Figure 2. X-ray crystal structure of 7a-CyHex-Ni (ORTEP plots,

ellipsoids at the 50% probability level). The unit cell contains two

diﬀerent rotamers, which are both depicted separately. Selected bond

lengths (Å) and angles (deg) for rotamer A: N1−Ni, 1.864(9); N2−

Ni, 1.868(11); O1−Ni, 1.813(10); O2−Ni, 1.812(9); Cl1−Pd,

2.369(3); Cl2−Pd, 2.362(4); C(N3,N4)-Pd, 1.897(13); C(N5,N6)-

Pd, 1.934(14); N1−Ni−N2, 87.2(4); N1−Ni−O1, 95.4(4); N2−Ni−

O2, 94.7(4); O1−Ni−O2, 82.7(4); Cl1−Pd−Cl2, 92.01(13); Cl1−

Pd−C(N3,N4), 87.5(4); Cl2−Pd−C(N5,N6), 86.8(4); C−Pd−C,

93.7(6). Selected bond lengths (Å) and angles (deg) for rotamer B:

N1−Ni, 1.857(9); N2−Ni, 1.859(10); O1−Ni, 1.855(9); O2−Ni,

1.854(9); Cl1−Pd, 2.335(4); Cl2−Pd, 2.348(4); C(N3,N4)-Pd,

2.072(11); C(N5,N6)-Pd, 2.010(11); N1−Ni−N2, 86.7(4); N1−

Ni−O1, 95.3(4); N2−Ni−O2, 95.2(4); O1−Ni−O2, 83.1(4); Cl1−

Pd−Cl2, 92.5(14); Cl1−Pd−C(N3,N4), 85.5(3); Cl2−Pd−C-

(N5,N6), 88.0(3); C−Pd−C, 94.0(4).

Scheme 3. Formation of Bimetallic Salen Bis-NHC Complex 11 Starting from Dibromide 9

116

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

Table 3. Anion Exchange by Silver Salts with Coordinating Counterions, Giving 12, or with “Non”-Coordinating Counterions,

Giving 13

a

entry

X

backbone

M¹

R¹

R²

R³

product type

color

yield (%)

77

1

PF₆

BF₄

CyHex

BiPh

Ni

Pd

Me

Ph

H

13

12

13

12

13

12

13

green

brown

green

yellow

red

2

78

3

CyHex

BiPh

94

4

OTf

89

b

5

OTs

O₂CC₃F₇

OAc

PF₆

93 [3.1:1]

95 [2.9:1]

6

b

7

orange

green

yellow

orange

green

yellow

red

>99 [3.4:1]

8

77

92

95

74

9

PF₆

Ph

10

11

12

13

14

15

16

17

18

19

20

21

BF₄

CyHex

BiPh

Ph

OTf

Ph

b

O₂CC₃F₇

OAc

PF₆

Ph

68 [12:1]

b

Ph

99 [11:1]

Mes

Me

Ph

89

81

93

89

PF₆

C₄H₄

BF₄

OTf

b

OTs

O₂CC₃F₇

OAc

PF₆

86 [2.3:1]

b

71 [1.9:1]

b

orange

red

97 [3.1:1]

H

>99

a

b

1

Yield of isolated product. Ratio of isomers determined by H NMR.

counterions the product yields showed signiﬁcant variations

from batch to batch, pointing to (partial) catalyst decom-

position, and the data shown in entries 3, 4, and 7−10 are thus

average data of ﬁve to seven runs. In contrast, the bis-Pd

catalyst 13a-CyHex-Pd-PF₆was found to give reproducible

results but showed a slightly lower catalytic activity (entries 5

and 6) in comparison to its Ni/Pd counterpart (see entries 3

and 4).

were readily transformed into heterobimetallic M¹/Ag(I)

complexes, which could be utilized for the preparation of

homo- and heterobimetallic M¹/Pd(II) complexes by an

oxidative transmetalation to Pd(0), whereas the more tradi-

tional transmetalation approach with Pd(II) sources or the

direct bis-NHC complexation of the corresponding bis-

imidazolium chloride salts failed. The initial chloride counter-

ions binding to M²= Pd^IIwith a cis geometry are readily

exchanged using diﬀerent silver salts, and the geometry of the

bimetallic complexes strongly depends on the coordination

behavior of the diﬀerent counterions, as revealed by X-ray and

UV−vis studies. In the absence of an anionic ligand with a

suitable Lewis basicity the salen oxygen atoms serve as bridging

ligands, whereas with coordinating counterions such as acetate

or tosylate a coordination behavior similar to that for chloride

was found. A preliminary investigation in catalysis showed that

the complexes are capable of catalyzing the 1,4-addition of

oxindoles to 2-nitrostyrene. Whereas the complexes with

hexaﬂuorophosphate counterions provided only moderate

product yields, the change to acetate counterions resulted in

quantitative yields. In both cases the products were racemic

mixtures of diastereomers. Currently, we are therefore studying

The choice of the counterion X⁻was found to have a large

impact on the catalyst activity. Catalyst 12b-CyHex-Ni-OAc

with acetate counterions provided the product in quantitative

yields (in all independent runs), but also in that case a racemate

was formed with moderate diastereoselectivity (entry 11).

Considerably less active was the catalyst 7b-CyHex-Ni, with

chloride counterions (entry 12). However, this complex

allowed for the highest diastereoselectivity.

CONCLUSION

■

In conclusion, we have developed a modular approach toward

salen bis-NHC hydrid ligands which are capable of forming

bimetallic complexes. Selective complexation of M¹= Pd^II, Ni^II

ions into the salen N₂O₂coordination site proceeded in

quantitative yields. The resulting Pd or Ni salen complexes

117

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

Figure 5. UV−vis spectra of 7a-CyHex-Ni (red curve), 12a-CyHex-

Ni-OAc (black curve), 12a-CyHex-Ni-OTs (pink curve), 12a-CyHex-

Ni-BF₄(green curve), and 12a-CyHex-Ni-PF₆(blue curve).

Figure 3. X-ray crystal structure of 13a-CyHex-Ni-PF₆(ORTEP plot,

ellipsoids at the 50% probability level, PF₆anions omitted for clarity).

Selected bond lengths (Å) and angles (deg): N1−Ni, 1.846(2); N2−

Ni, 1.849(2); O1−Ni, 1.8803(17); O2−Ni, 1.8734(18); O1−Pd,

2.1343(19); O2−Pd, 2.1168(17); C(N3,N5)-Pd, 1.955(2); C-

(N4,N6)-Pd, 1.945(3); N1−Ni−N2, 86.03(10); N1−Ni−O1,

95.48(9); N2−Ni−O2, 95.81(9); O1−Ni−O2, 85.56(8); O1−Pd−

O2, 73.69(7); O1−Pd−C(N3,N5), 99.19(10); O2−Pd−C(N4,N6),

99.90(9); C−Pd−C, 87.70(11).

a great tendency to include solvent residues, which could not be

completely removed. In addition, the silver complexes 6-M¹display a

limited stability.

General Procedure for the Synthesis of Aldehydes 3. 3-

(Chloromethyl)-5-tert-butyl-2-hydroxybenzaldehyde (2; 1.0 equiv)

was dissolved in acetonitrile (10 mL/g aldehyde 2), and the

corresponding heterocycle (1.05 equiv) was added. The mixture was

stirred for 24 h. Subsequently diethyl ether (30 mL/g aldehyde) was

added to cause precipitation. The mixture was ﬁltered, and the ﬁlter

cake was washed with diethyl ether. The resulting solid 3 was dried in

vacuo (0.1 mbar), and no further puriﬁcation was necessary.

(5-tert-Butyl-3-formyl-2-hydroxybenzyl)-1-methyl-1H-imidazol-3-

ium Chloride (3a). Aldehyde 3a was prepared according to the general

procedure. 3-(Chloromethyl)-5-tert-butyl-2-hydroxybenzaldehyde (2;

1.00 g, 4.41 mmol, 1.0 equiv) was treated with 1-methylimidazole

(0.38 g, 0.37 mL, 4.62 mmol, 1.05 equiv). Compound 3a (1.10 g, 3.57

mmol, 81%) was isolated as a colorless solid.

1

C₁₆H₂₁ClN₂O₂mol wt: 308.80. Mp: 204.6−205.6 °C. H NMR

(500 MHz, CDCl₃, 21 °C): δ 11.32 (s, 1 H, C_ArOH), 10.79 (s, 1 H,

NCHN_Imid), 9.87 (s, 1 H, CHO), 8.23 (d, J = 2.6, 1 H, CH_Ar), 7.56 (d,

J = 2.6, 1 H, CH_Ar), 7.54 (t, J = 1.7, 1 H, NCH_Imid), 7.47 (t, J = 1.7, 1

H, NCH_Imid), 5.62 (s, 2 H, C_ArCH₂), 4.01 (s, 3 H, NCH₃), 1.29 (s, 9 H,

C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ 196.5, 157.1, 143.9, 137.7,

136.8, 131.2, 123.2, 122.4, 121.5, 120.2, 47.2, 36.4, 34.2, 31.1 (3×). IR

(solid): v 3058, 3043, 2969, 2953, 1650, 1557, 1475, 1384, 1272, 1225,

̃

1157, 1008, 773, 713, 674. HRMS (ESI) m/z: calcd for [M − Cl]⁺

C₁₆H₂₁N₂O₂: 273.1598; found, 273.1603. Anal. Calcd for

[C₁₆H₂₁ClN₂O₂]: C, 62.23; H, 6.85. Found: C, 62.30; H, 6.81.

3-(5-tert-Butyl-3-formyl-2-hydroxybenzyl)-1-phenyl-1H-imidazol-

3-ium Chloride (3b). Aldehyde 3b was prepared according to the

general procedure. 3-(Chloromethyl)-5-tert-butyl-2-hydroxybenzalde-

hyde (2; 1.00 g, 4.41 mmol, 1.0 equiv) was treated with 1-

phenylimidazole (0.67 g, 4.62 mmol, 1.05 equiv). Compound 3b

(1.64 g, 4.42 mmol, 84%) was isolated as a beige solid.

Figure 4. X-ray crystal structure of 13d-CyHex-Ni-PF₆(ORTEP plot,

ellipsoids at the 50% probability level, PF₆anions, embedded

dichloromethane, and a second, slightly diﬀerent conformer in the

unit cell omitted for clarity). Selected bond lengths (Å) and angles

(deg): N1A−Ni1A, 1.867(12); N2A−Ni1A, 1.850(11); O1A−Ni1A,

1.873(9); O2A−Ni1A, 1.891(10); O1A−Pd1A, 2.093(9); O2A−

Pd1A, 2.130(8); C(N3A,N4A)−Pd1A, 1.975(15); C(N5A,N6A)−

Pd1A, 1.957(14); N1A−Ni1A−N2A, 87.3(5); N1A−Ni1A−O1A,

94.0(5); N2A−Ni1A−O2A, 95.7(4); O1A−Ni1A−O2A, 85.4(4);

O1A−Pd1A−O2A, 74.4(4); O1A−Pd1A−C(N3A,N4C), 96.7(5);

O2A−Pd1A−C(N5A,N6A), 99.4(5); C−Pd1A−C, 90.2(6).

1

C₂₁H₂₃ClN₂O₂mol wt: 370.87. Mp: 240.0−241.8 °C. H NMR

(500 MHz, CDCl₃, 21 °C): δ 11.49 (s, 1 H, NCHN_Imid), 11.35 (s, 1 H,

C_ArOH), 9.86 (s, 1 H, CHO), 8.41 (d, J = 2.2, 1 H, CH_Ar), 7.89 (t, J =

1.8,1 H, NCH_Imid), 7.73 (t, J = 1.8, 1 H, NCH_Imid), 7.71−7.69 (m, 2 H,

CH_Ph), 7.54 (d, J = 2.4, 1 H, CH_Ar), 7.44−7.35 (m, 3 H, CH_Ph), 5.81

(s, 2 H, C_ArCH₂), 1.26 (s, 9 H, C(CH₃)₃). ¹³C NMR (125 MHz,

CDCl₃): δ 196.7, 157.2, 144.1, 137.5, 136.3, 134.3, 131.3, 130.3 (2×),

129.9, 123.5, 121.5, 121.4 (2×), 120.3, 120.2, 47.5, 34.3, 31.1 (3×). IR

the potential of these and related bimetallic salen bis-NHC

complexes in alternative asymmetric reactions.

(solid): v 3027, 2947, 1652, 1549, 1454, 1284, 1232, 1199, 1067, 1015,

̃

762, 719, 688. HRMS (ESI) m/z: calcd for [M − Cl]⁺C₂₁H₂₃N₂O₂,

335.1754; found, 335.1751. Anal. Calcd for [C₂₁H₂₃ClN₂O₂]: C,

68.01; H, 6.25. Found: C, 67.90; H, 6.23.

EXPERIMENTAL SECTION

■

Despite many puriﬁcation trials and excessive drying under high

vacuum, the microanalyses of the bis-cationic ligands 4, the bis-cationic

monometal complexes 5-M¹, and the bimetallic complexes 6-M¹, 7-

M¹, 12-M¹, and 13-M¹were not satisfying. All these compounds have

3-(5-tert-Butyl-3-formyl-2-hydroxybenzyl)-1-mesityl-1H-imida-

zol-3-ium Chloride (3c). Aldehyde 3c was prepared according to the

general procedure. 3-(Chloromethyl)-5-tert-butyl-2-hydroxybenzalde-

118

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

Table 4. Investigation of the 1,4-Addition of Oxindole 14 to 2-Nitrostyrene

a

b

entry

cat. type

M¹

R¹

additive (10 mol %)

yield (%)

dr

nd

1

<2

4

2

HOAc

n.d.

3

13a-CyHex-Ni-PF₆

13a-CyHex-Pd-PF₆

13b-CyHex-Ni-PF₆

13c-CyHex-Ni-PF₆

12b-CyHex-Ni-OAc

Ni

Pd

Ni

Me

Ph

45

41

33

20

59

62

32

28

>99

35

74:26

71:29

73:27

70:30

74:26

75:25

76:24

73:31

66:34

83:17

4

5

6

7

8

Ph

9

Mes

Ph

10

11

12

7b-CyHex-Ni

Ph

a

b

1

Yield of isolated product. Determined by H NMR.

hyde (2; 1.06 g, 4.68 mmol, 1.0 equiv) was treated with 1-

mesitylimidazole (0.92 g, 4.91 mmol, 1.05 equiv). Compound 3c

(1.93 g, 4.67 mmol, 73%) was isolated as a beige solid.

121.0, 120.2, 114.0, 112.7, 45.1, 34.4, 33.8, 31.3 (3×). IR (solid): v

2954, 2868, 1676, 1482, 1470, 1218, 1193, 792, 757, 749, 713. HRMS

(ESI) m/z: calcd. for [M − Cl]⁺C₂₀H₂₃N₂O₂, 323.1754; found,

323.1748. Anal. Calcd for [C₂₀H₂₃ClN₂O₂]: C, 66.94; H, 6.46. Found:

C, 66.60; H, 6.42.

General Procedure for the Synthesis of Bis-Imidazolium

Salen Ligands 4. To a solution of aldehyde 3 (2.0 equiv) in ethanol

(5 mL/g aldehyde 3) were added (1R,2R)-(−)-1,2-diaminocyclohex-

ane (1.0 equiv) or (1R,2R)-diamino-1,1′-dimethylbiphenyl (1.0 equiv)

and molecular sieves (4 Å). The mixture was stirred for 20 h at

ambient temperature. After ﬁltration, EtOH was removed in vacuo.

Subsequent repetitive azeotropic removal of residual EtOH with DCM

gave 4 as an orange foam.

(R,R)-(−)-N,N′-Bis(3-tert-butyl-5-((1-methyl-1H-imidazol-3-ium)-

1-ylmethyl)salicylidene)-1,2-cyclohexanediamine Dichloride (4a-

CyHex). salen ligand 4a-CyHex was prepared according to the general

procedure. (1R,2R)-Diaminocyclohexane (0.16 g, 1.44 mmol, 1.0

equiv) was treated with aldehyde 3a (0.89 g, 2.87 mmol, 2.0 equiv).

Compound 4a-CyHex (0.99 g, 1.44 mmol, 100%) was isolated as a

yellow solid.

̃

C₂₄H₂₉ClN₂O₂mol wt: 412.95. Mp: >200 °C. ¹H NMR (500 MHz,

CDCl₃, 21 °C): δ 11.43 (s, 1 H, NCHN_Imid), 10.80 (s, 1 H, C_ArOH),

9.94 (s, 1 H, CHO), 8.56 (d, J = 2.5, 1 H, CH_Ar), 7.89 (t, J = 1.6,1 H,

NCH_Imid), 7.62 (d, J = 2.5, 1 H, CH_Ar), 7.13 (t, J = 1.6, 1 H, NCH_Imid),

6.97 (s, 2 H, C_MesH), 6.05 (s, 2 H, C_ArCH₂), 2.32 (s, 3 H, p-CH₃C_Mes),

2.03 (s, 6 H, o-CH₃C_Mes), 1.35 (s, 9 H, C(CH₃)₃). ¹³C NMR (125

MHz, CDCl₃): δ 195.8, 155.5, 142.5, 139.3, 136.9, 132.2, 129.2, 128.9,

128.1, 127.9 (2×), 121.4, 120.9, 120.3, 118.4, 45.7, 32.6, 29.4 (3×),

19.2, 15.7 (2×). IR (solid): v 2939, 1646, 1620, 1540, 1479, 1446,

̃

1314, 1299, 1284, 1215, 1194, 1162, 1012, 857, 753, 722, 672, 648,

632, 578, 539. HRMS (ESI) m/z: calcd for [M − Cl]⁺C₂₄H₂₉N₂O₂,

377.2224; found, 377.2234. Anal. Calcd for [C₂₄H₂₉ClN₂O₂]: C,

69.80; H, 7.08. Found: C, 69.65; H, 7.02.

3-(5-tert-Butyl-3-formyl-2-hydroxybenzyl)-1-methyl-1H-benzo-

[d]imidazol-3-ium Chloride (3d). Aldehyde 3d was prepared

according to the general procedure. 3-(Chloromethyl)-5-tert-butyl-2-

hydroxybenzaldehyde (2; 0.50 g, 2.21 mmol, 1.0 equiv) was treated

with 1-methylbenzimidazole (0.31 g, 2.32 mmol, 1.05 equiv).

Compound 3d (0.74 g, 2.05 mmol, 93%) was isolated as a beige solid.

C₃₈H₅₂Cl₂N₆O₂mol wt: 695.76. Mp: 179.2−180.3 °C dec. [α]²⁰

=

D

−203.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

13.85 (s, 2 H, C_ArOH), 10.65 (s, 2 H, NCHN_Imid), 8.33 (s, 2 H, N

CH), 7.71 (d, J = 2.5, 2 H, CH_Ar), 7.32 (t, J = 1.8, 2 H, NCH_Imid),

7.22−7.21 (m, 4 H, CH_Ar, NCH_Imid), 5.44 (d, J = 13.9, 2 H, C_ArCH₂),

5.40 (d, J = 13.9, 2 H, C_ArCH₂), 3.98 (s, 6 H, NCH₃), 3.38−3.36 (m, 2

H, N(CH)_Ring), 1.92−1.89 (m, 2 H, (CH₂)_Ring), 1.86−1.84 (m, 2 H,

(CH₂)_Ring), 1.67−1.61 (m, 2 H, (CH₂)_Ring), 1.45−1.41 (m, 2 H,

(CH₂)_Ring), 1.19 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ

1

C₂₀H₂₃ClN₂O₂mol wt: 358.86. Mp: 238.0−238.7 °C. H NMR

(500 MHz, CDCl₃, 21 °C): δ 11.74 (s, 1 H, NCHN_Imid), 11.33 (s, 1 H,

C_ArOH), 9.83 (s, 1 H, CHO), 8.25 (d, J = 2.5, 1 H, CH_Ar), 7.93 (d, J =

7.8, 1 H, CH_Imid), 7.68 (d, J = 7.8, 1 H, CH_Imid), 7.46−7.54 (m, 2 H,

CH_Imid), 7.52 (d, J = 2.5, 1 H, CH_Ar), 5.84 (s, 2 H, C_ArCH₂), 4.32 (s, 3

H, NCH₃), 1.28 (s, 9 H, C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ

196.7, 157.1, 144.3, 144.2, 136.8, 131.8, 131.4, 131.2, 127.13, 127.09,

119

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

164.7, 157.8, 142.1, 138.2, 132.0, 129.7, 122.9, 122.2, 120.7, 118.2,

HRMS (ESI) m/z: calcd for [M − Cl]⁺C₄₆H₅₆ClN₆O₂, 759.4148;

found, 759.4166.

71.7, 48.3, 36.6, 34.2, 33.0, 31.5 (3×), 24.2. IR (solid): v 2946, 2860,

̃

1627, 1479, 1447, 1280, 1226, 1156, 1014, 826, 727, 676, 610. HRMS

(ESI) m/z: calcd for [M − Cl]⁺C₃₈H₅₂ClN₆O₂, 659.3835; found,

659.3836.

(R)-(−)-N,N′-Bis(3-tert-butyl-5-((1-methyl-1H-imidazol-3-ium)-1-

ylmethyl)salicylidene)diamino-1,1′-dimethylbiphenyl Dichloride

(4a-BiPh). salen ligand 4a-BiPh was prepared according to the

general procedure. (1R,2R)-Diamino-1,1′-dimethylbiphenyl (0.42 g,

1.97 mmol, 1.0 equiv) was treated with aldehyde 3a (1.21 g, 3.93

mmol, 2.0 equiv). Compound 4a-BiPh (1.56 g, 1.97 mmol, 100%) was

isolated as a yellow solid.

(R,R)-(−)-N,N′-Bis(3-tert-butyl-5-((1-phenyl-1H-imidazol-3-ium)-

1-ylmethyl)salicylidene)-1,2-cyclohexanediamine Dichloride (4b-

CyHex). salen ligand 4b-CyHex was prepared according to the

general procedure. (1R,2R)-Diaminocyclohexane (0.18 g, 1.56 mmol,

1.0 equiv) was treated with aldehyde 3b (1.16 g, 3.13 mmol, 2.0

equiv). Compound 4b-CyHex (1.28 g, 1.56 mmol, 100%) was isolated

as a yellow solid.

C₄₆H₅₄Cl₂N₆O₂mol wt: 793.87. Mp: 169.3−171.0 °C dec. [α]²⁰

=

D

−579.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

13.17 (s, 2 H, C_ArOH), 10.56 (s, 2 H, NCHN_Imid), 8.64 (s, 2 H, N

CH), 7.75 (d, J = 2.5, 2 H, CH_Ar), 7.41 (t, J = 7.9, 2 H, CH_BiPh), 7.38−

7.37 (m, 2 H, CH_BiPh, 2 H NCH_Imid), 7.26−7.25 (m, 2 H, CH_BiPh, 2 H

CH_Ar), 7.23 (t, J = 1.6, 2 H, NCH_Imid), 5.42 (d, J = 13.9, 2 H, C_ArCH₂),

5.38 (d, J = 13.9, 2 H, C_ArCH₂), 4,02 (s, 6 H, NCH₃), 2,00 (s, 6 H,

C_BiPhCH₃), 1.25 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ

161.1, 157.3, 145.4, 142.5, 138.0, 137.8, 134.1, 132.5, 130.2, 129.1,

128.6, 122.6 (3×), 120.8, 118.7, 115.1, 48.2, 36.5, 34.2, 31.4 (3×),

1

C₄₈H₅₆Cl₂N₆O₂mol wt: 819.90. Mp: 189.4−192.3 °C dec. [α]²⁰

=

D

−136.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

13.92 (s, 2 H, C_ArOH), 11.54 (s, 2 H, NCHN_Imid), 8.35 (s, 2 H, N

CH), 8.04 (d, J = 2.5, 2 H, CH_Ar), 7.65−7.64 (m, 4 H, CH_Ph), 7.60 (t, J

= 1.8, 2 H, NCH_Imid), 7.42−7.39 (m, 4 H, CH_Ph, 2 H, NCH_Imid), 7.32−

7.30 (m, 2 H, CH_Ph), 7.21 (d, J = 2.5, 2 H, CH_Ar), 5.73 (d, J = 13.8, 2

H, C_ArCH₂), 5.63 (d, J = 13.8, 2 H, C_ArCH₂), 3.40−3.38 (m, 2 H,

N(CH)_Ring), 1.94−1.91 (m, 2 H, (CH₂)_Ring), 1.87−1.85 (m, 2 H,

(CH₂)_Ring), 1.69−1.62 (m, 2 H, (CH₂)_Ring), 1.46−1.42 (m, 2 H,

(CH₂)_Ring), 1.19 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ

164.7, 157.9, 142.4, 136.6, 134.3, 132.8, 130.6 (2 × C), 129.9, 129.6,

123.2, 121.4 (2 × C), 121.0, 119.8, 118.1, 71.8, 48.3, 34.3, 33.0, 31.5

1

19.9. IR (solid): v 3358, 2954, 2866, 1620, 1596, 1461, 1364, 1280,

̃

1220, 1158, 1015, 786, 748, 677, 619. HRMS (ESI) m/z: calcd for [M

− Cl]⁺C₄₆H₅₄ClN₆O₂, 757.3991; found, 757.3960.

(R)-(−)-N,N′-Bis(3-tert-butyl-5-((1-phenyl-1H-imidazol-3-ium)-1-

ylmethyl)salicylidene)diamino-1,1′-dimethylbiphenyl Dichloride

(4b-BiPh). salen ligand 4b-BiPh was prepared according to the

general procedure. (1R,2R)-Diamino-1,1′-dimethylbiphenyl (0.49 g,

2.30 mmol, 1.0 equiv) was treated with aldehyde 4b (1.71 g, 4.60

mmol, 2.0 equiv). Compound 4b-BiPh (2.11 g, 2.30 mmol, 100%) was

isolated as a yellow solid.

(3×), 24.2. IR (solid): v 2947, 2861, 1628, 1598, 1548, 1494, 1480,

̃

1463, 1445, 1364, 1281, 1217, 1070, 758, 686. HRMS (ESI) m/z:

calcd for [M − Cl]⁺C₄₈H₅₆ClN₆O₂, 783.4148; found, 783.4138.

(R,R)-(−)-N,N′-Bis(3-tert-butyl-5-((1-mesityl-1H-imidazol-3-ium)-

1-ylmethyl)salicylidene)-1,2-cyclohexanediamine Dichloride (4c-

CyHex). salen ligand 4c-CyHex was prepared according to the general

procedure. (1R,2R)-Diaminocyclohexane (0.14 g, 1.24 mmol, 1.0

equiv) was treated with aldehyde 3c (1.03 g, 2.49 mmol, 2.0 equiv).

Compound 4c-CyHex (1.12 g, 1.24 mmol, 100%) was isolated as a

yellow solid.

C₅₆H₅₈Cl₂N₆O₂mol wt: 918.00. Mp: 203.0−204.5 °C dec. [α]²⁰

=

D

−347.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

13.33 (s, 2 H, C_ArOH), 11.42 (s, 2 H, NCHN_Imid), 8.69 (s, 2 H, N

CH), 8.08 (d, J = 2.5, 2 H, CH_Ar), 7.71−7.70 (m, 4 H, CH_Ph), 7.67 (t, J

= 1.6, 2 H, NCH_Imid), 7.48−7.45 (m, 4 H, CH_Ph), 7.46−7.37 (m, 2 H,

CH_Ph, 2 H, CH_Ar, 2 H, NCH_Imid), 7.34 (t, J = 7.9, 2 H, CH_BiPh), 7.27

(d, J = 7.0, 2 H, CH_BiPh), 7.23 (d, J = 7.0, 2 H, CH_BiPh), 5.68 (d, J =

13.7, 2 H, C_ArCH₂), 5.60 (d, J = 13.7, 2 H, C_ArCH₂), 2,00 (s, 6 H,

C_BiPhCH₃), 1.25 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ

160.9, 157.5, 145.2, 142.7, 137.9, 136.4, 134.4, 134.2, 133.3, 130.5 (2 ×

C), 130.2, 130.0, 129.1, 128.6, 123.6, 121.5 (2×), 121.1, 119.6, 118.6,

1

C₅₄H₆₈Cl₂N₆O₂mol wt: 904.06. Mp: 171.5−173.0 °C dec. [α]²⁰

=

D

−235.5° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

13.81 (s, 2 H, C_ArOH), 10.71 (s, 2 H, NCHN_Imid), 8.30 (s, 2 H, N

CH), 7.89 (d, J = 2.5, 2 H, CH_Ar), 7.60 (t, J = 1.6, 2 H, NCH_Imid), 7.18

(d, J = 2.5, 2 H, CH_Ar), 7.02 (t, J = 1.6, 2 H, NCH_Imid), 6.89 (s, 4 H,

C_MesH), 5.87 (d, J = 14.1, 2 H, C_ArCH₂), 5.81 (d, J = 14.1, 2 H,

C_ArCH₂), 3.36−3.34 (m, 2 H, N(CH)_Ring), 2.24 (s, 6 H, p-CH₃C_Mes),

1.95 (s, 6 H, o-CH₃C_Mes), 1.94 (s, 6 H, o-CH₃C_Mes), 1.89−1.84 (m, 4

H, (CH₂)_Ring), 1.67−1.60 (m, 2 H, (CH₂)_Ring), 1.46−1.42 (m, 2 H,

(CH₂)_Ring), 1.18 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ

164.8, 157.7, 142.3, 141.1, 138.9, 134.2, 132.3, 130.9, 129.8 (2 × C),

129.3, 123.0, 122.7, 121.3, 118.1, 71.9, 48.4, 34.2, 33.1, 31.4 (3×), 24.1,

1

115.0, 48.4, 34.3, 31.4 (3×), 19.9. IR (solid): v 2952, 1619, 1597, 1562,

̃

1548, 1461, 1364, 1280, 1215, 1071, 1043, 1014, 785, 758, 686, 634.

HRMS (ESI) m/z: calcd for [M − Cl]⁺C₅₆H₅₈ClN₆O, 881.4304;

found, 881.4301.

(R)-(−)-N,N′-Bis(3-tert-butyl-5-((1-mesityl-1H-imidazol-3-ium)-1-

ylmethyl)salicylidene)diamino-1,1′-dimethylbiphenyl Dichloride

(4c-BiPh). salen ligand 4c-BiPh was prepared according to the general

procedure. (1R,2R)-Diamino-1,1′-dimethylbiphenyl (0.18 g, 0.85

mmol, 1.0 equiv) was treated with aldehyde 3c (0.70 g, 1.70 mmol,

2.0 equiv). Compound 4c-BiPh (0.77 g, 0.85 mmol, 100%) was

isolated as a yellow solid.

21.1, 17.6. IR (solid): v 2948, 2863, 1627, 1543, 1480, 1444, 1363,

̃

1282, 1226, 1198, 1156, 1066, 1036, 852, 826, 789, 750, 670, 648, 578,

555. HRMS (ESI) m/z: calcd for [M − Cl]⁺C₅₄H₆₈ClN₆O₂,

867.5087; found, 867.5068.

(R,R)-(−)-N,N′-Bis(3-tert-butyl-5-((1-methyl-1H-benzo[d]-

imidazol-3-ium)-1-ylmethyl)salicylidene)-1,2-cyclohexanediamine

Dichloride (4d-CyHex). salen ligand 4d-CyHex was prepared

according to the general procedure. (1R,2R)-Diaminocyclohexane

(0.19 g, 1.66 mmol, 1.0 equiv) was treated with aldehyde 3d (1.16 g,

3.31 mmol, 2.0 equiv). Compound 4d-CyHex (1.31 g, 1.66 mmol,

100%) was isolated as a yellow solid.

C₆₂H₇₀Cl₂N₆O₂mol wt: 1002.16. Mp: 210.0−212.0 °C dec. [α]²⁰

D

= −408.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CDCl₃): δ

13.20 (s, 2 H, C_ArOH), 10.50 (s, 2 H, NCHN_Imid), 8.63 (s, 2 H, N

CH), 8.06 (d, J = 2.5, 2 H, CH_Ar), 7.74 (t, J = 1.6, 2 H, NCH_Imid), 7.36

(d, J = 2.5, 2 H, CH_Ar), 7.28 (t, J = 8.3, 2 H, CH_BiPh), 7.18 (t, J = 7.1, 4

H, CH_BiPh), 7.09 (t, J = 1.6, 2 H, NCH_Imid), 6.97 (s, 2 H, CH_Mes), 6.95

(s, 2 H, CH_Mes), 5.87 (d, J = 14.0, 2 H, C_ArCH₂), 5.77 (d, J = 14.0, 2 H,

C_ArCH₂), 2.32 (s, 6 H, p-CH₃C_Mes), 2,00 (s, 6 H, C_BiPhCH₃), 1.99 (s,

12 H, o-CH₃C_Mes), 1.26 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz,

CDCl₃): δ 161.1, 157.3, 145.4, 142.8, 141.2, 138.4, 137.7, 134.2, 134.1,

133.3, 130.9, 129.9, 129.8 (2 × C), 129.0, 128.5, 123.6, 122.4, 121.5,

C₃₈H₅₂Cl₂N₆O₂mol wt: 795.88. Mp: 191.5−192.7 °C dec. [α]²⁰

=

D

−182.5° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

13.85 (s, 2 H, C_ArOH), 11.65 (s, 2 H, NCHN_Imid), 8.30 (s, 2 H, N

CH), 7.74 (d, J = 8.3, 2 H, CH_Imid), 7.64 (d, J = 2.5, 2 H, CH_Ar), 7.56

(d, J = 8.3, 2 H, CH_Imid), 7.47 (t, J = 7.6, 2 H, CH_Imid), 7.33 (t, J = 7.6,

2 H, CH_Imid), 7.20 (d, J = 2.5, 2 H, CH_Ar), 5.73 (d, J = 14.7, 2 H,

C_ArCH₂), 5.52 (d, J = 14.7, 2 H, C_ArCH₂), 4.24 (s, 6 H, NCH₃), 3.39−

3.37 (m, 2 H, N(CH)_Ring), 1.81−1.79 (m, 4 H, (CH₂)_Ring), 1.67−1.60

(m, 2 H, (CH₂)_Ring), 1.43−1.39 (m, 2 H, (CH₂)_Ring), 1.19 (s, 18 H,

C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ 164.8, 157.9, 144.4, 141.8,

132.0, 131.12, 131.09, 129.7 (3×), 126.8, 119.6, 118.3, 113.9, 112.6,

1

118.6, 114.9, 48.2, 34.3, 31.4 (3×), 21.1, 19.9. IR (solid): v 2953, 2864,

̃

1619, 1597, 1562, 1544, 1460, 1364, 1281, 1220, 1199, 1156, 1066,

1040, 1013, 852, 785, 749, 670, 648, 638, 578. HRMS (ESI) m/z:

calcd for [M − Cl]⁺C₆₂H₇₀ClN₆O₂, 965.5243; found, 965.5234.

General Procedure for the Synthesis of Mono-Metal

Complexes 5-M¹. To the corresponding ligand 4 dissolved in

CH₂Cl₂(0.1 mmol in 20 mL) were added the corresponding metal salt

(NiCl₂or Pd(OAc)₂, 1.0 equiv) and NaOAc (2.0 equiv). The

72.0, 46.7, 34.1, 33.7, 33.3, 31.4 (3×), 24.1. IR (solid): v 2951, 1628,

̃

1565, 1463, 1364, 1281, 1226, 1141, 1092, 1015, 827, 741, 646, 616.

120

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

suspension was stirred for 24−48 h at room temperature or 30 °C.

Solutions of 5-Ni were then ﬁltered through a pad of Celite and

solutions of 5-Pd through a thin pad of Al₂O₃(activity I), and the

products were eluted with CH₂Cl₂/MeOH (40/1). The solvent was

removed by rotary evaporation, and the resulting solids 5-M¹were

dried in vacuo (0.1 mbar).

[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

imidazol-3-ium]](2−)]palladium(II) Dichloride (5a-Pd-CyHex).

Complex 5a-Pd-CyHex was prepared according to the general

procedure. Ligand 4a-CyHex (139.15 mg, 0.20 mmol, 1.0 equiv)

was used, and the mixture was stirred for 24 h at room temperature.

Compound 5a-Pd-CyHex (160.03 mg, 0.20 mmol, 100%) was isolated

as a yellow solid.

HRMS (ESI) m/z: calcd for [M − Cl]⁺C₄₈H₅₄ClN₆O₂Pd, 887.3040;

found, 887.3023.

[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-

3,1-phenylenr]methylenr]bis[1-phenyl-1H-imidazol-3-ium]-6,6′-di-

methyl-1,1′-biphenyl](2−)]palladium(II) Dichloride (5b-Pd-BiPh).

Complex 5b-Pd-BiPh was prepared according to the general

procedure. Ligand 4b-BiPh (114.75 mg, 0.125 mmol, 1.0 equiv) was

used, and the mixture was stirred for 24 h at room temperature.

Compound 5b-Pd-BiPh (127.80 mg, 0.125 mmol, 100%) was isolated

as an orange solid.

C₅₆H₅₆Cl₂N₆O₂Pd mol wt: 1022.41. Mp: >200.0 °C dec. [α]²⁰

=

D

−747.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

11.17 (s, 2 H, NCHN_Imid), 8.21 (s, 2 H, NCH), 8.09 (d, J = 2.5, 2 H,

CH_Ar), 7.78 (br, 2 H, NCH_Imid), 7.68 (d, J = 7.5, 4 H, CH_Ph), 7.41−

7.34 (m, 4 H, CH_Ph, 2 H, CH_BiPh, 2 H, NCH_Imid), 7.31 (t, J = 7.6, 2 H,

CH_BiPh), 7.23 (d, J = 2.5, 2 H, CH_Ar), 6.79 (d, J = 7.5, 2 H, CH_BiPh),

5.78 (d, J = 13.4, 2 H, C_ArCH₂), 5.68 (d, J = 13.4, 2 H, C_ArCH₂), 2.01

(s, 6 H, C_BiPhCH₃), 1.28 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz,

CDCl₃): δ 161.7, 161.5, 148.0, 139.9, 138.9, 137.4, 134.6, 131.4, 130.6,

130.4 (2×), 129.8, 129.5, 124.4, 124.1, 122.6, 122.4, 121.7 (2×), 120.4,

1

C₃₈H₅₀Cl₂N₆O₂Pd mol wt: 800.17. Mp: 237.0−238.5 °C dec. [α]²⁰

D

= −177.8° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CDCl₃): δ

10.27 (s, 2 H, NCHN_Imid), 7.80 (s, 2 H, NCH), 7.75 (t, J = 1.6, 2 H,

NCH_Imid), 7.70 (d, J = 2.5, 2 H, CH_Ar), 7.64 (t, J = 1.6, 2 H, NCH_Imid),

7.25 (d, J = 2.5, 2 H, CH_Ar), 5.48 (s, 4 H, C_ArCH₂), 3.94 (s, 6 H,

NCH₃), 3.46−3.43 (m, 2 H, N(CH)_Ring), 2.71−2.67 (m, 2 H,

(CH₂)_Ring), 2.00−1.97 (m, 2 H, (CH₂)_Ring), 1.59−1.55 (m, 2 H,

(CH₂)_Ring), 1.42−1.39 (m, 2 H, (CH₂)_Ring), 1.21 (s, 18 H, C(CH₃)₃).

¹³C NMR (125 MHz, CDCl₃): δ 161.3, 156.3, 138.4, 137.7, 136.3,

132.5, 124.4, 123.4, 122.9, 120.7, 72.6, 50.4, 36.5, 33.6, 31.4 (3×), 28.8,

50.1, 34.1, 31.3 (3×), 19.5. IR (solid): v 3367, 3055, 2956, 2866, 2360,

̃

1728, 1615, 1596, 1544, 1495, 1439, 1366, 1314, 1272, 1240, 1212,

1071, 1050, 1021, 956, 836, 820, 794, 760, 737, 689, 635, 610. HRMS

(ESI) m/z: calcd for [M − 2Cl]²⁺C₅₆H₅₆N₆O₂Pd, 475.1754; found,

475.1739.

24.5. IR (solid): v 3374, 2949, 2863, 1620, 1541, 1452, 1364, 1319,

̃

[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

benzo[d]imidazol-3-ium]](2−)]palladium(II) Dichloride (5d-Pd-

CyHex). Complex 5d-Pd-CyHex was prepared according to the

general procedure. Ligand 4d-CyHex (39.79 mg, 0.05 mmol, 1.0

equiv) was used, and the mixture was stirred for 24 h at room

temperature. Compound 5d-Pd-CyHex (45.01 mg, 0.05 mmol, 100%)

was isolated as a yellow solid.

1270, 1252, 1219, 1154, 1040, 832, 796, 735, 676. HRMS (ESI) m/z:

calcd for [M − Cl]⁺C₃₈H₅₀ClN₆O₂Pd, 763.2704; found, 763.2724.

[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-

3,1-phenylene]methylene]bis[1-methyl-1H-imidazol-3-ium]-6,6′-di-

methyl-1,1′-biphenyl](2−)]palladium(II) Dichloride (5a-Pd-BiPh).

Complex 5a-Pd-BiPh was prepared according to the general

procedure. Ligand 4a-BiPh (39.69 mg, 0.05 mmol, 1.0 equiv) was

used, and the mixture was stirred for 24 h at room temperature.

Compound 5a-Pd-BiPh (44.90 mg, 0.05 mmol, 100%) was isolated as

an orange solid.

C₄₆H₅₄Cl₂N₆O₂Pd mol wt: 900.29. Mp: 183.6−193.6 °C dec. [α]²⁰

D

= −519.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (300 MHz, CDCl₃): δ

10.86 (s, 2 H, NCHN_Imid), 7.99 (d, J = 7.9, 2 H, CH_Imid), 7.84 (s, 2 H,

NCH), 7.78 (d, J = 2.5, 2 H, CH_Ar), 7.58 (d, J = 7.9, 2 H, CH_Imid),

7.49−7.43 (m, 4 H, CH_Imid), 7.31 (d, J = 2.5, 2 H, CH_Ar), 6.2 (d, J =

14.6, 2 H, C_ArCH₂), 5.55 (d, J = 14.6, 2 H, C_ArCH₂), 4.06 (s, 6 H,

NCH₃), 3.45−3.43 (m, 2 H, N(CH)_Ring), 2.69−2.67 (m, 2 H,

(CH₂)_Ring), 1.93−1.91 (m, 2 H, (CH₂)_Ring), 1.55−1.53 (m, 2 H,

(CH₂)_Ring), 1.43−1.37 (m, 2 H, (CH₂)_Ring), 1.25 (s, 18 H, C(CH₃)₃).

¹³C NMR (125 MHz, CDCl₃): δ 161.1, 156.7, 144.6, 138.4, 134.9,

132.8, 131.8, 131.4, 126.72, 126.68, 123.3, 121.2, 114.0, 112.8, 72.4,

C₄₆H₅₂Cl₂N₆O₂Pd mol wt: 898.27. Mp: 160.0−162.0 °C dec. [α]²⁰

D

= −720.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CDCl₃): δ

10.37 (s, 2 H, NCHN_Imid), 7.87 (br, 2 H, NCH_Imid), 7.78 (d, J = 2.5, 2

H, CH_Ar), 7.45 (br, 2 H, NCH_Imid), 7.42 (s, 2 H, NCH), 7.37 (d, J =

7.5, 2 H, CH_BiPh), 7.31 (t, J = 7.7, 2 H, CH_BiPh), 6.86 (d, J = 7.5, 2 H,

CH_BiPh), 5.42 (d, J = 13.6, 2 H, C_ArCH₂), 5.30 (d, J = 13.6, 2 H,

C_ArCH₂), 3.94 (s, 6 H, NCH₃), 2,03 (s, 6 H, C_BiPhCH₃), 1.26 (s, 18 H,

C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ 176.4, 161.9, 161.6, 148.0,

139.5, 138.9, 138.2, 136.8, 131.5, 130.6, 129.6, 129.5, 124.3, 123.3,

122.8 (2×), 122.6, 49.5, 36.2, 33.9, 31.2 (3×), 23.3, 19.5. IR (solid): v

2961, 1712, 1614, 1594, 1573, 1543, 1445, 1365, 1329, 1265, 1241,

1215, 1160, 1094, 1049, 1016, 908, 837, 819, 796, 729, 650, 620.

HRMS (ESI) m/z: calcd for [M − 2Cl]²⁺C₄₆H₅₄N₆O₂Pd, 413.1596;

found, 413.1591.

48.7, 33.9, 33.8, 31.4 (3×), 29.0, 24.4. IR (solid): v 2947, 1620, 1564,

̃

1541, 1443, 1389, 1364, 1345, 1317, 1269, 1253, 1220, 1196, 1095,

1039, 1013, 923, 833, 747, 724, 548. HRMS (ESI) m/z: calcd for [M

− Cl]⁺C₄₆H₅₄ClN₆O₂Pd, 863.3029; found, 863.3039.

[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

imidazol-3-ium]](2−)]nickel(II) Dichloride (5a-Ni-CyHex). Complex

5a-Ni-CyHex was prepared according to the general procedure.

Ligand 4a-CyHex (278.30 mg, 0.40 mmol, 1.0 equiv) was used, and

the mixture was stirred for 24 h at room temperature. Compound 5a-

Ni-CyHex (300.98 mg, 0.40 mmol, 100%) was isolated as a red solid.

[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-

imidazol-3-ium]](2−)]palladium(II) Dichloride (5b-Pd-CyHex).

Complex 5b-Pd-CyHex was prepared according to the general

procedure. Ligand 4b-CyHex (245.97 mg, 0.30 mmol, 1.0 equiv)

was used, and the mixture was stirred for 24 h at room temperature.

Compound 5b-Pd-CyHex (277.29 mg, 0.30 mmol, 100%) was

isolated as a yellow solid.

C₃₈H₅₀Cl₂N₆NiO₂mol wt: 752.44. Mp: 156.3−157.4 °C dec. [α]²⁰

D

= −519.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CDCl₃): δ

10.31 (s, 2 H, NCHN_Imid), 7.89 (s, 2 H, NCH_Imid), 7.64 (s, 2 H,

NCH_Imid), 7.62 (d, J = 2.5, 2 H, CH_Ar), 7.53 (s, 2 H, NCH), 7.20 (d,

J = 2.5, 2 H, CH_Ar), 5.37 (d, J = 13.9, 2 H, C_ArCH₂), 5.28 (d, J = 13.9,

2 H, C_ArCH₂), 4.00 (s, 6 H, NCH₃), 3.09−3.08 (m, 2 H, N(CH)_Ring),

2.54−2.52 (m, 2 H, (CH₂)_Ring), 1.97−1.96 (m, 2 H, (CH₂)_Ring), 1.40−

1.35 (m, 4 H, (CH₂)_Ring), 1.23 (s, 18 H, C(CH₃)₃). ¹³C NMR (125

MHz, CDCl₃): δ 159.1, 157.2, 137.5, 136.5, 133.4, 129.6, 122.7, 122.5,

122.1, 119.0, 69.3, 48.6, 35.5, 32.8, 30.3 (3×), 27.9, 23.3. IR (solid): v

3368, 2954, 2860, 1780, 1620, 1548, 1454, 1333, 1258, 1224, 1156,

1098, 1047, 1013, 795, 615, 553. HRMS (ESI) m/z: calcd for [M −

Cl]⁺C₃₈H₅₀ClN₆NiO₂, 715.3032; found, 715.3031.

C₄₈H₅₄Cl₂N₆O₂Pd mol wt: 924.31. Mp: 183.9−185.6 °C dec. [α]²⁰

D

= −355.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CDCl₃): δ

11.26 (s, 2 H, NCHN_Imid), 8.02 (t, J = 1.6, 2 H, NCH_Imid), 7.97−7.96

(m, 2 H, NCH, 2 H, CH_Ar), 7.89 (t, J = 1.6, 2 H, NCH_Imid), 7.76−

7.74 (m, 4 H, CH_Ph), 7.42−7.34 (m, 6 H, CH_Ph, 2 H, CH_Ar), 5.76 (d, J

= 13.5, 2 H, C_ArCH₂), 5.70 (d, J = 13.5, 2 H, C_ArCH₂), 3.53−3.50 (m,

2 H, N(CH)_Ring), 2.78−2.74 (m, 2 H, (CH₂)_Ring), 2.05−2.02 (m, 2 H,

(CH₂)_Ring), 1.64−1.61 (m, 2 H, (CH₂)_Ring), 1.49−1.42 (m, 2 H,

(CH₂)_Ring), 1.30 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ

161.3, 156.4, 138.7, 136.6, 135.7, 134.7, 132.6, 130.4 (2 × C), 129.7,

124.4, 123.8, 121.6 (2 × C), 120.7, 120.4, 72.7, 50.7, 34.0, 31.4 (3× C),

̃

[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-

3,1-phenylene]methylene]bis[1-methyl-1H-imidazol-3-ium]-6,6′-di-

methyl-1,1′-biphenyl](2−)]nickel(II) Dichloride (5a-Ni-BiPh). Com-

28.9, 24.2. IR (solid): v 2948, 2862, 1621, 1542, 1444, 1390, 1364,

̃

1318, 1271, 1253, 1202, 1070, 1041, 833, 793, 756, 686, 633, 554.

121

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

plex 5a-Ni-BiPh was prepared according to the general procedure.

Ligand 4a-BiPh (39.69 mg, 0.05 mmol, 1.0 equiv) was used, and the

mixture was stirred for 24 h at room temperature. Compound 5a-Ni-

BiPh (42.53 mg, 0.05 mmol, 100%), a green-brown solid, was directly

used for the preparation of the corresponding Ag−carbene complex.

2861, 1714, 1621, 1545, 1455, 1390, 1364, 1328, 1256, 1226, 1199,

1157, 1051, 924, 853, 836, 796, 724, 670, 638, 578, 554. HRMS (ESI)

m/z: calcd for [M − Cl]⁺C₅₄H₆₆ClN₆NiO₂, 923.4284; found,

923.4280.

[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

benzo[d]imidazol-3-ium]](2−)]nickel(II) Dichloride (5d-Ni-CyHex).

Complex 5d-Ni-CyHex was prepared according to the general

procedure. Ligand 4d-CyHex (318.35 mg, 0.40 mmol, 1.0 equiv)

was used, and the mixture was stirred for 48 h at 30 °C. Compound

5d-Ni-CyHex (360.12 mg, 0.40 mmol, 100%) was isolated as a red

solid.

C₄₆H₅₂Cl₂N₆NiO₂mol wt: 850.54. Mp: 155.0−160.0 °C dec. [α]²⁰

D

1

= −190.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (300 MHz, CDCl₃):

paramagnetic species, very broad signals. ¹³C NMR (125 MHz,

CDCl ): paramagnetic species. IR (solid): v 3379, 2956, 2867, 1766,

̃

3

1720, 1620, 1571, 1539, 1458, 1380, 1364, 1271, 1214, 1160, 1038,

1019, 802, 751, 678, 621, 562. HRMS (ESI) m/z: calcd for [M − Cl]⁺

C₄₆H₅₂ClN₆NiO₂, 813.3188; found, 813.3164.

C₄₆H₅₄Cl₂N₆NiO₂mol wt: 852.56. Mp: 172.0−173.5 °C dec. [α]²⁰

D

[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-

imidazol-3-ium]](2−)]nickel(II) Dichloride (5b-Ni-CyHex). Complex

5b-Ni-CyHex was prepared according to the general procedure.

Ligand 4b-CyHex (327.96 mg, 0.40 mmol, 1.0 equiv) was used, and

the mixture was stirred for 48 h at 30 °C. Compound 5b-Ni-CyHex

(350.63 mg, 0.40 mmol, 100%) was isolated as a red solid.

= −505.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (300 MHz, CD₂Cl₂): δ

11.03 (s, 2 H, NCHN_Imid), 8.10 (d, J = 8.2, 2 H, CH_Imid), 7.72−7.66

(m, 6 H, NCH, CH_Ar, CH_Imid), 7.60−7.53 (m, 4 H, CH_Imid), 7.29 (d,

J = 2.5, 2 H, CH_Ar), 5.82 (d, J = 14.0, 2 H, C_ArCH₂), 5.58 (d, J = 14.0,

2 H, C_ArCH₂), 4.12 (s, 6 H, NCH₃), 3.11−3.10 (m, 2 H, N(CH)_Ring),

2.52−2.49 (m, 2 H, (CH₂)_Ring), 1.96−1.93 (m, 2 H, (CH₂)_Ring), 1.36−

1.33 (m, 4 H, (CH₂)_Ring), 1.25 (s, 18 H, C(CH₃)₃). ¹³C NMR (125

MHz, CD₂Cl₂): δ 161.8, 160.6, 146.1, 140.2, 135.7, 133.9, 133.2,

132.5, 128.6 (2×), 124.7, 122.3, 116.1, 114.6, 72.1, 49.3, 35.7, 33.0

C₄₈H₅₄Cl₂N₆NiO₂mol wt: 876.58. Mp: 261.1−262.5 °C dec. [α]²⁰

D

= −401.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CDCl₃): δ

11.02 (s, 2 H, NCHN_Imid), 8.10 (s, 2 H, NCH_Imid), 7.93 (s, 2 H,

NCH_Imid), 7.83 (d, J = 2.5, 2 H, CH_Ar), 7.71−7.70 (m, 4 H, CH_Ph),

7.55 (s, 2 H, NCH), 7.39−7.33 (m, 6 H, CH_Ph), 7.23 (d, J = 2.5, 2

H, CH_Ar), 5.61 (d, J = 14.0, 2 H, C_ArCH₂), 5.57 (d, J = 14.0, 2 H,

C_ArCH₂), 3.11−3.10 (m, 2 H, N(CH)_Ring), 2.56−2.54 (m, 2 H,

(CH₂)_Ring), 1.97−1.96 (m, 2 H, (CH₂)_Ring), 1.40−1.37 (m, 4 H,

(CH₂)_Ring), 1.26 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ

159.1, 157.4, 137.6, 135.3, 134.0, 133.6, 129.7, 129.4 (2 × C), 128.7,

123.1, 122.7, 120.5 (2 × C), 119.5, 119.1, 69.3, 49.2, 32.9, 30.4 (3×),

(3×), 30.9, 26.2. IR (solid): v 2925, 2857, 1619, 1548, 1457, 1365,

̃

1259, 1197, 1091, 1013, 799, 751, 660, 616. HRMS (ESI) m/z: calcd

for [M − Cl]⁺C₄₆H₅₄ClN₆NiO₂, 815.3345; found, 815.3326.

General Procedure for the Synthesis of Ag−Carbene

Complexes 6-M¹. The monometal complexes 5-M¹(1.0 equiv)

were dissolved in 1,2-dichloroethane (0.1 mmol in 20 mL), and Ag₂O

(2.0 equiv) was added. The suspension was stirred for 20 h at 55 °C.

Subsequently the mixture was cooled to room temperature and the

excess of Ag₂O was removed by ﬁltration through a pad of Celite. The

solvent was removed by rotary evaporation, and the resulting solids 6-

M¹were dried in vacuo (0.1 mbar).

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]palladium(II)}silver(I) Dichloroar-

gentate(1−) (6a-Pd-CyHex). Complex 6a-Pd-CyHex was prepared

according to the general procedure, and monopalladium complex 5a-

Pd-CyHex (40.01 mg, 0.05 mmol, 1.0 equiv) was used. Ag−carbene

complex 6a-Pd-CyHex (50.69 mg, 0.05 mmol, 100%) was isolated as a

yellow solid.

28.0, 23.3. IR (solid): v 3051, 2956, 2932, 2862, 1737, 1619, 1549,

̃

1461, 1442, 1345, 1322, 1254, 1224, 1183, 1103, 1071, 1052, 800, 791,

766, 757, 686, 637, 558. HRMS (ESI) m/z: calcd for [M − Cl]⁺

C₄₈H₅₄ClN₆NiO₂, 839.3345; found, 839.3343.

[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-κO)-

3,1-phenylene]methylene]bis[1-phenyl-1H-imidazol-3-ium]-6,6′-di-

methyl-1,1′-biphenyl](2−)]nickel(II) Dichloride (5b-Ni-BiPh). Com-

plex 5b-Ni-BiPh was prepared according to the general procedure.

Ligand 4b-BiPh (114.75 mg, 0.13 mmol, 1.0 equiv) was used, and the

mixture was stirred for 24 h at room temperature. Compound 5b-Ni-

BiPh (121.84 mg, 0.13 mmol, 100%), a green-brown solid, was

directly used for the preparation of the corresponding Ag−carbene

complex.

C₃₈H₄₈Ag₂Cl₂N₆O₂Pd mol wt: 1013.89. Mp: 231.2−231.8 °C dec.

1

[α]²⁰= −310.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz,

D

CDCl₃): δ 7.80 (s, 2 H, NCH), 7.63 (br, 2 H, NCH_Imid), 7.44 (d, J =

2.5, 2 H, CH_Ar), 7.22 (d, J = 2.5, 2 H, CH_Ar), 7.00 (s, 2 H, NCH_Imid),

5.32 (d, J = 14.0, 2 H, C_ArCH₂), 5.28 (d, J = 14.0, 2 H, C_ArCH₂), 3.74

(s, 6 H, NCH₃), 3.49−3.47 (m, 2 H, N(CH)_Ring), 2.68−2.66 (m, 2 H,

(CH₂)_Ring), 1.99−1.97 (m, 2 H, (CH₂)_Ring), 1.57−1.55 (m, 2 H,

(CH₂)_Ring), 1.41−1.37 (m, 2 H, (CH₂)_Ring), 1.25 (s, 18 H, C(CH₃)₃).

¹³C NMR (125 MHz, CDCl₃): δ 179.3, 161.6, 156.0, 137.9, 133.8,

131.2, 127.0, 213.2, 121.8, 120.2, 72.7, 52.59, 38.7, 33.8, 31.4 (3×),

C₅₆H₅₆Cl₂N₆NiO₂mol wt: 974.68. Mp: 160.0−163.0 °C dec. [α]²⁰

D

1

= −291.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (300 MHz, CDCl₃):

paramagnetic species, very broad signals. ¹³C NMR (125 MHz,

CDCl ): paramagnetic species. IR (solid): v 3376, 3135, 3052, 2959,

̃

3

2869, 1736, 1620, 1598, 1567, 1550, 1518, 1495, 1462, 1365, 1275,

1218, 1070, 1043, 1020, 760, 689, 656, 644, 627, 603, 588, 575, 555,

563. HRMS (ESI) m/z: calcd for [M − Cl]⁺C₅₆H₅₆ClN₆NiO₂,

937.3501; found, 937.3492.

28.8, 24.5, 22.4. IR (solid): v 2947, 2863, 1620, 1539, 1446, 1389,

̃

[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-mesityl-1H-

imidazol-3-ium]](2−)]nickel(II) Dichloride (5c-Ni-CyHex). Complex

5c-Ni-CyHex was prepared according to the general procedure.

Ligand 4c-CyHex (113.01 mg, 0.125 mmol, 1.0 equiv) was used, and

the mixture was stirred for 12 h at 30 °C. Compound 5c-Ni-CyHex

(120.09 mg, 0.125 mmol, 100%) was isolated as a red solid.

1363, 1317, 1268, 1213, 1042, 833, 799, 734, 646, 605. HRMS (ESI)

m/z: calcd for [M − (Cl−Ag−Cl)]⁺C₃₈H₄₈AgN₆O₂Pd, 835.1930;

found, 835.1928.

{[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-

κO)-3,1-phenylene]methylene]bis[1-methyl-1H-imidazol-1-yl-2(3H)-

ylidene]-6,6′-dimethyl-1,1′-biphenyl](2−)]palladium(II)}silver(I)

Dichloroargentate(1−) (6a-Pd-BiPh). Complex 6a-Pd-BiPh was

prepared according to the general procedure, and monopalladium

complex 5a-Pd-BiPh (22.46 mg, 0.03 mmol, 1.0 equiv) was used. Ag−

carbene complex 6a-Pd-BiPh (22.8 mg, 0.02 mmol, 82%) was isolated

as a orange solid.

C₅₄H₆₆Cl₂N₆NiO₂mol wt: 960.74. Mp: >200 °C dec. [α]²⁰

=

D

−337.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

10.46 (s, 2 H, NCHN_Imid), 8.25 (br, 2 H, NCH_Imid), 7.93 (d, J = 2.5, 2

H, CH_Ar), 7.60 (s, 2 H, NCH), 7.25 (br, 2 H, NCH_Imid, 2 H, CH_Ar),

6.91 (d, J = 14.2, 4 H, CH_Mes), 5.99 (d, J = 12.9, 2 H, C_ArCH₂), 5.86

(d, J = 12.9, 2 H, C_ArCH₂), 3.13−3.11 (m, 2 H, N(CH)_Ring), 2.62−2.60

(m, 2 H, (CH₂)_Ring), 2.26 (s, 6 H, p-CH₃C_Mes), 2.17 (s, 6 H, o-

CH₃C_Mes), 2.08 (s, 6 H, o-CH₃C_Mes), 2.00−1.99 (m, 4 H, (CH₂)_Ring),

1.44−1.40 (m, 2 H, (CH₂)_Ring), 1.27 (s, 18 H, C(CH₃)₃). ¹³C NMR

(125 MHz, CDCl₃): δ 160.1, 156.5, 140.9, 139.0, 138.8, 134.9, 134.4,

134.3, 130.9, 130.6, 129.7 (2×), 124.3, 123.9, 123.1, 119.9, 70.4, 50.4,

1

C₄₆H₅₀Ag₂Cl₂N₆O₂Pd mol wt: 1111.99. Mp: >200 °C dec. [α]²⁰

=

D

−529.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

7.84 (br, 2 H, NCH_Imid), 7.48 (d, J = 2.5, 2 H, CH_Ar), 7.41 (s, 2 H,

NCH), 7.34 (d, J = 7.7, 2 H, CH_BiPh), 7.28 (t, J = 7.7, 2 H, CH_BiPh),

7.17 (d, J = 2.5, 2 H, CH_Ar), 7.02 (d, J = 1.5, 2 H, NCH_Imid), 6.82 (d, J

= 7.6, 2 H, CH_BiPh), 5.30 (d, J = 13.9, 2 H, C_ArCH₂), 5.12 (d, J = 13.9,

2 H, C_ArCH₂), 3.79 (s, 6 H, NCH₃), 2,02 (s, 6 H, C_BiPhCH₃), 1.25 (s,

18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ 156.5, 156.1, 142.9,

1

33.4, 31.4 (3×), 29.3, 24.4, 21.4, 18.9 (2×), 17.9. IR (solid): v 2950,

̃

122

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

133.6, 133.4, 129.4, 125.0, 124.9, 124.4, 124.3, 124.0, 121.5, 117.9,

117.3, 117.1, 117.0, 46.7, 33.4, 28.6, 25.9, 24.4 (3×), 14.2. IR (solid): v

2949, 2922, 2855, 1613, 1593, 1573, 1539, 1449, 1434, 1403, 1363,

1310, 1269, 1231, 1207, 1111, 1051, 1019, 953, 881, 837, 819, 797,

776, 734, 703, 662, 624, 590, 568, 549, 532, 502. HRMS (ESI) m/z:

calcd for [M − (Cl−Ag−Cl)]⁺C₄₆H₅₀AgN₆O₂Pd, 933.2089; found,

933.2092.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]palladium(II)}silver(I) Dichloroar-

gentate(1−) (6b-Pd-CyHex). Complex 6b-Pd-CyHex was prepared

according to the general procedure, and monopalladium complex 5b-

Pd-CyHex (277.29 mg, 0.30 mmol, 1.0 equiv) was used. Ag−carbene

complex 6b-Pd-CyHex (313.00 mg, 0.27 mmol, 91%) was isolated as a

yellow solid.

1040, 943, 868, 835, 799, 743. HRMS (ESI) m/z: calcd for [M − (Cl−

Ag−Cl)]⁺: C₄₆H₅₂AgN₆O₂Pd, 935.2245; found, 935.2237.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}silver(I) Dichloroargen-

tate(1−) (6a-Ni-CyHex). Complex 6a-Ni-CyHex was prepared

according to the general procedure, and mononickel complex 5a-Ni-

CyHex (188.11 mg, 0.25 mmol, 1.0 equiv) was used. Ag−carbene

complex 6a-Ni-CyHex (241.54 mg, 0.25 mmol, 100%) was isolated as

a red solid.

̃

C₃₈H₄₈Ag₂Cl₂N₆NiO₂mol wt: 966.16. Mp: 218.4−219.2 °C dec.

1

[α]²⁰= −401.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz,

D

CDCl₃): δ 7.71 (d, J = 1.6, 2 H, NCH_Imid), 7.49 (s, 2 H, NCH), 7.32

(d, J = 2.5, 2 H, CH_Ar), 7.12 (d, J = 2.5, 2 H, CH_Ar), 7.02 (d, J = 1.6, 2

H, NCH_Imid), 5.18 (d, J = 14.1, 2 H, C_ArCH₂), 5.10 (d, J = 14.1, 2 H,

C_ArCH₂), 3.76 (s, 6 H, NCH₃), 3.06−3.05 (m, 2 H, N(CH)_Ring), 2.51−

2.49 (m, 2 H, (CH₂)_Ring), 1.95−1.94 (m, 2 H, (CH₂)_Ring), 1.37−1.33

(m, 4 H, (CH₂)_Ring), 1.22 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz,

CDCl₃): δ 177.9, 159.4, 157.0, 136.9, 131.7, 128.4, 125.3, 122.3, 121.1,

C₄₈H₅₂Ag₂Cl₂N₆O₂Pd mol wt: 1138.03. Mp: 212.7−214.8 °C dec.

1

[α]²⁰= −282.5° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz,

D

CDCl₃): δ 7.93 (br, 2 H, NCH_Imid), 7.83 (s, 2 H, NCH), 7.62 (br, 2

H, CH_Ar), 7.50−7.48 (m, 4 H, CH_Ph), 7.45−7.35 (m, 6 H, CH_Ph), 7.28

(d, J = 2.5, 2 H, CH_Ar), 7.21 (br, J = 2.5, 2 H, NCH_imid), 5.52 (d, J =

13.8, 2 H, C_ArCH₂), 5.43 (d, J = 13.8, 2 H, C_ArCH₂), 3.50−3.48 (m, 2

H, N(CH)_Ring), 2.70−2.67 (m, 2 H, (CH₂)_Ring), 2.01−1.99 (m, 2 H,

(CH₂)_Ring), 1.56−1.49 (m, 2 H, (CH₂)_Ring), 1.43−1.37 (m, 2 H,

(CH₂)_Ring), 1.28 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ

179.0, 161.6, 156.2, 139.9, 138.1, 134.3, 131.7, 130.5, 129.9, 129.8 (2 ×

C), 128.7, 126.5, 123.9, 123.8 (2 × C), 121.6, 121.2, 120.5, 72.6, 53.2,

118.6, 69.2, 51.1, 37.7, 32.8, 30.4 (3×), 27.9, 23.3. IR (solid): v 2945,

̃

2861, 1737, 1618, 1547, 1449, 1337, 1220, 1042, 800, 737, 554. HRMS

(ESI) m/z: calcd for [M − (Cl−Ag−Cl)]⁺C₃₈H₄₈AgN₆NiO₂,

787.2232; found, 787.2227.

{[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-

κO)-3,1-phenylene]methylene]bis[1-methyl-1H-imidazol-1-yl-2(3H)-

ylidene]-6,6′-dimethyl-1,1′-biphenyl](2−)]nickel(II)}silver(I)

Dichloroargentate(1−) (6a-Ni-BiPh). Complex 6a-Ni-BiPh was

prepared according to the general procedure, and mononickel complex

5a-Ni-BiPh (42.20 mg, 0.05 mmol, 1.0 equiv) was used. Ag−carbene

complex 6a-Ni-BiPh (36.70 mg, 0.03 mmol, 70%), a red solid, was

directly used for the transmetalation.

33.9, 33.72, 31.4 (3× C), 31.0, 28.8, 26.9, 24.5. IR (solid): v 2947,

̃

2861, 1619, 1598, 1538, 1497, 1441, 1410, 1388, 1362, 1317, 1268,

1237, 1212, 1097, 1042, 833, 797, 734, 692, 554, 542. HRMS (ESI) m/

z: calcd for [M − (Cl−Ag−Cl)]⁺C₄₈H₅₂AgN₆O₂Pd, 959.2246; found,

959.2253.

C₄₆H₅₀Ag₂Cl₂N₆NiO₂mol wt: 1064.26. Mp: >200.0 °C dec. [α]²⁰

D

{[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-

κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-imidazol-1-yl-2(3H)-

ylidene]-6,6′-dimethyl-1,1′-biphenyl](2−)] palladium(II)}silver(I) Di-

chloroargentate(1−) (6b-Pd-BiPh). Complex 6b-Pd-BiPh was

prepared according to the general procedure, and monopalladium

complex 5b-Pd-BiPh (25.56 mg, 0.03 mmol, 1.0 equiv) was used. Ag−

carbene complex 6b-Pd-BiPh (30.9 mg, 0.03 mmol, 100%) was

isolated as an orange solid.

1

= −206.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (300 MHz, CDCl₃):

paramagnetic species, very broad signals. ¹³C NMR (125 MHz,

CDCl ): paramagnetic species. IR (solid): v 2949, 2863, 1768, 1617,

̃

3

1594, 1574, 1534, 1449, 1377, 1363, 1270, 1229, 1204, 1164, 1109,

1035, 991, 882, 836, 803, 773, 757, 735, 690, 660, 620, 592, 529, 517.

HRMS (ESI) m/z: calcd for [M − (Cl−Ag−Cl)]⁺C₄₆H₅₀AgN₆NiO₂,

885.2386; found, 885.2372.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}silver(I) Dichloroargen-

tate(1−) (6b-Ni-CyHex). Complex 6b-Ni-CyHex was prepared

according to the general procedure, and mononickel complex 5b-Ni-

CyHex (43.83 mg, 0.05 mmol, 1.0 equiv) was used. Ag−carbene

complex 6b-Ni-CyHex (54.52 mg, 0,04 mmol, 84%) was isolated as a

red solid.

C₅₆H₅₄Ag₂Cl₂N₆O₂Pd mol wt: 1236.13. Mp: >200 °C dec. [α]²⁰

=

D

−671.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

7.70 (d, J = 2.5, 2 H, CH_Ar), 7.50−7.26 (m, 4 H, NCH_Imid, 10 H, CH_Ph,

2 H, NCH), 7.22 (d, J = 2.5, 2 H, CH_Ar), 6.85 (d, J = 7.3, 2 H,

CH_BiPh), 5.49 (d, J = 13.3, 2 H, C_ArCH₂), 5.31 (d, J = 13.3, 2 H,

C_ArCH₂), 2.03 (s, 6 H, C_BiPhCH₃), 1.28 (s, 18 H, C(CH₃)₃). ¹³C NMR

(125 MHz, CDCl₃): δ 161.9, 161.5, 148.2, 139.9, 139.2, 138.8, 135.4,

130.6, 130.4, 129.92, 129.88 (2×), 129.6, 129.4, 128.8, 126.6, 123.9

(2×), 122.6, 122.5, 121.8, 121.5, 52.6, 34.0, 31.3 (3×), 19.5. IR (solid):

1

C₄₈H₅₂Ag₂Cl₂N₆NiO₂mol wt: 1090.30. Mp: 201.5−202.4 °C dec.

1

[α]²⁰= −438.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz,

D

v 2950, 2926, 2861, 1733, 1613, 1595, 1537, 1498, 1447, 1437, 1412,

̃

CDCl₃): δ 8.05 (br, 2 H, NCH_Imid), 7.53 (br, 2 H, CH_Ar, 2 H, N

CH), 7.51−7.49 (m, 4 H, CH_Ph), 7.47−7.37 (m, 6 H, CH_Ph), 7.28 (d, J

= 1.6, 2 H, NCH_imid), 7.18 (d, J = 2.5, 2 H, CH_Ar), 5.37 (d, J = 14.0, 2

H, C_ArCH₂), 5.28 (d, J = 14.0, 2 H, C_ArCH₂), 3.08−3.07 (m, 2 H,

N(CH)_Ring), 2.53−2.51 (m, 2 H, (CH₂)_Ring), 1.97−1.96 (m, 2 H,

(CH₂)_Ring), 1.39−1.33 (m, 4 H, (CH₂)_Ring), 1.26 (s, 18 H, C(CH₃)₃).

¹³C NMR (125 MHz, CDCl₃): δ 177.2, 159.5, 157.1, 138.9, 137.3,

132.3, 128.8 (2×), 128.7, 127.7, 125.1, 123.1, 122.9 (2×), 120.5, 118.8,

1392, 1363, 1304, 1269, 1236, 1208, 1106, 1051, 1019, 955, 837, 796,

758, 734, 534. HRMS (ESI) m/z: calcd for [M − (Cl−Ag−Cl)]⁺

C₅₆H₅₄AgN₆O₂Pd, 1057.2405; found, 1057.2408.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

benzo[d]imidazol-1-yl-2(3H)-ylidene]](2−)]palladium(II)}silver(I)

Dichloroargentate(1−) (6d-Pd-CyHex). Complex 6d-Pd-CyHex was

prepared according to the general procedure, and monopalladium

complex 5d-Pd-CyHex (45.01 mg, 0.05 mmol, 1.0 equiv) was used.

Ag−carbene complex 6d-Pd-CyHex (48.6 mg, 0.04 mmol, 87%) was

isolated as a yellow solid.

69.3, 51.7, 32.8, 30.4 (3×), 27.9, 23.3. IR (solid): v 2947, 1619, 1547,

̃

1497, 1453, 1338, 1271, 1221, 1050, 799, 739, 691, 558. HRMS (ESI)

m/z: calcd for [M − (Cl−Ag−Cl)]⁺C₄₈H₅₂AgN₆NiO₂, 911.2543;

found, 911.2533.

C₄₆H₅₂Ag₂Cl₂N₆O₂Pd mol wt: 1114.01. Mp: >200 °C dec. [α]²⁰

=

D

{[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-

κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-imidazol-1-yl-2(3H)-

ylidene]-6,6′-dimethyl-1,1′-biphenyl](2−)]nickel(II)}silver(I)

Dichloroargentate(1−) (6b-Ni-BiPh). Complex 6b-Ni-BiPh was

prepared according to the general procedure, and mononickel complex

5b-Ni-BiPh (23.70 mg, 0.02 mmol, 1.0 equiv) was used. Ag−carbene

complex 6b-Ni-BiPh (25.40 mg, 0.02 mmol, 88%), a red solid, was

directly used for the transmetalation.

−271.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (300 MHz, CDCl₃): δ

8.04−7.04 (m, 8 H, CH_Imid, 4 H, CH_Ar), 7.74 (s, 2 H, NCH), 5.47

(br, 4 H, C_ArCH₂), 3.79 (br, 6 H, NCH₃), 3.54−3.43 (m, 2 H,

N(CH)_Ring), 2.63−2.59 (m, 2 H, (CH₂)_Ring), 1.94−1.92 (m, 2 H,

(CH₂)_Ring), 1.40−1.32 (m, 4 H, (CH₂)_Ring), 1.11 (s, 18 H, C(CH₃)₃).

¹³C NMR (125 MHz, CDCl₃): δ 185.3, 159.2, 154.2, 135.4, 132.2,

131.8 (2×), 129.6, 122.0 (3×), 118.5, 111.9, 108.5, 70.7, 46.7, 41.6,

1

31.8, 29.4 (3×), 26.8, 22.5. IR (solid): v 2946, 2860, 1737, 1622, 1542,

C₅₆H₅₄Ag₂Cl₂N₆NiO₂mol wt: 1188.40. Mp: >200.0 °C dec. [α]²⁰

̃

D

1

1442, 1387, 1363, 1342, 1326, 1303, 1264, 1244, 1202, 1130, 1094,

= −301.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (300 MHz, CDCl₃):

123

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

paramagnetic species, very broad signals. ¹³C NMR (125 MHz,

CH_Ar), 7.26 (d, J = 2.5, 2 H, CH_Ar), 6.72 (d, J = 1.9, 2 H, NCH_Imid),

6.36 (d, J = 1.9, 2 H, NCH_Imid), 5.62 (d, J = 13.0, 2 H, C_ArCH₂), 4.88

(d, J = 13.0, 2 H, C_ArCH₂), 4.26 (s, 6 H, NCH₃), 2.26−2.24 (m, 2 H,

N(CH)_Ring), 2.65−2.63 (m, 2 H, (CH₂)_Ring), 2.00−1.99 (m, 2 H,

(CH₂)_Ring), 1.56−1.50 (m, 2 H, (CH₂)_Ring), 1.40−1.36 (m, 2 H,

(CH₂)_Ring), 1.32 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃,

main isomer): δ 162.9, 159.3, 155.1, 136.9, 134.5, 131.1, 125.3, 121.5,

120.6, 119.5, 71.9, 52.5, 39.3, 33.8, 31.5 (3×), 28.6, 24.5. IR (solid): v

2950, 2861, 1616, 1537, 1455, 1403, 1364, 1326, 1266, 1213, 1196,

1093, 1033, 793, 730, 705, 686, 666, 556. HRMS (ESI) m/z: calcd for

[M − Cl]⁺C₃₈H₄₈ClN₆O₂Pd₂, 869.1606; found, 869.1605.

{[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-

κO)-3,1-phenylene]methylene]bis[1-methyl-1H-imidazol-1-yl-2(3H)-

ylidene]-6,6′-dimethyl-1,1′-biphenyl](2−)]palladium(II)}palladium-

(II) Dichloride (7a-Pd-BiPh). Complex 7a-Pd-BiPh was prepared

according to the general procedure, and Ag−carbene complex 6a-Pd-

BiPh (22.80 mg, 0.02 mmol, 1.0 equiv) was used. Bimetallic complex

7a-Pd-BiPh (11.10 mg, 0.01 mmol, 54%, dr = 10:1) was isolated as an

orange solid.

CDCl ): paramagnetic species. IR (solid): v 2953, 1730, 1619, 1597,

̃

3

1573, 1538, 1515, 1498, 1457, 1411, 1380, 1364, 1271, 1237, 1210,

1063, 1043, 1020, 958, 883, 836, 803, 761, 736, 693, 552. HRMS (ESI)

m/z: calcd for [M − (Cl−Ag−Cl)]⁺C₅₆H₅₄AgN₆NiO₂, 1009.2702;

found, 1009.2681.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-mesityl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}silver(I) Dichloroargen-

tate(1−) (6c-Ni-CyHex). Complex 6c-Ni-CyHex was prepared

according to the general procedure, and mononickel complex 5c-Ni-

CyHex (110.00 mg, 0.12 mmol, 1.0 equiv) was used. Ag−carbene

complex 6c-Ni-CyHex (134.47 mg, 0,12 mmol, 100%) was isolated as

a red solid.

̃

C₅₄H₆₄Ag₂Cl₂N₆NiO₂mol wt: 1174.46. Mp: >200 °C dec. [α]²⁰

=

D

−435.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

7.85 (br, 2 H, NCH_Imid), 7.51 (s, 2 H, NCH), 7.32 (d, J = 2.5, 2 H,

CH_Ar), 7.13 (d, J = 2.5, 2 H, CH_Ar), 6.98 (br, 2 H, NCH_imid), 6.90−

6.89 (m, 4 H, CH_Mes), 5.41 (d, J = 14.1, 2 H, C_ArCH₂), 5.31 (d, J =

14.1, 2 H, C_ArCH₂), 3.11−3.09 (m, 2 H, N(CH)_Ring), 2.52−2.50 (m, 2

H, (CH₂)_Ring), 2.29 (s, 6 H, p-CH₃C_Mes), 1.98−1.96 (m, 2 H,

(CH₂)_Ring), 1.92 (s, 6 H, o-CH₃C_Mes), 1.91 (s, 6 H, o-CH₃C_Mes), 1.39−

1.34 (m, 4 H, (CH₂)_Ring), 1.22 (s, 18 H, C(CH₃)₃). ¹³C NMR (125

MHz, CDCl₃): δ 178.8 (d, J = 257.4), 158.8, 156.5, 137.8, 136.5, 134.0,

133.2, 133.1, 130.7, 127.89, 127.85, 127.6, 125.1, 121.4, 121.3, 118.1,

1

C₄₆H₅₀Cl₂N₆O₂Pd₂mol wt: 1002.67. Mp: >200 °C dec. [α]²⁰

=

D

−524.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

7.43 (d, J = 2.5, 2 H, CH_Ar), 7.32−7.23 (m, 4 H, CH_BiPh, 2 H, N

CH), 7.19 (d, J = 2.5, 2 H, CH_Ar), 6.72 (d, J = 1.9, 2 H, NCH_Imid), 6.66

(d, J = 7.4, 2 H, CH_BiPh), 7.49 (d, J = 1.9, 2 H, NCH_Imid), 5.25 (d, J =

12.8, 2 H, C_ArCH₂), 4.83 (d, J = 12.8, 2 H, C_ArCH₂), 4.23 (s, 6 H,

NCH₃), 1.96 (s, 6 H, C_BiPhCH₃), 1.27 (s, 18 H, C(CH₃)₃). ¹³C NMR

(125 MHz, CDCl₃): δ 163.6, 160.8, 158.3, 148.4, 138.8, 137.7, 135.9,

130.4, 130.1, 129.8, 129.2, 124.4, 122.8, 122.3, 121.6, 119.6, 51.6, 39.1,

1

68.7, 50.4, 32.3, 29.8 (3×), 27.4, 22.9, 19.6, 16.3. IR (solid): v 2948,

̃

2859, 1802, 1773, 1738, 1619, 1547, 1449, 1409, 1389, 1362, 1340,

1310, 1272, 1221, 1161, 1105, 1073, 1040, 935, 852, 837, 799, 737.

HRMS (ESI) m/z: calcd for [M − (Cl−Ag−Cl)]⁺C₅₄H₆₄AgN₆NiO₂,

995.3484; found, 995.3480.

33.8, 31.3 (3×), 19.5. IR (solid): v 3469, 2953, 2866, 2358, 2342,

̃

1616, 1593, 1573, 1541, 1460, 1450, 1366, 1323, 1271, 1211, 1126,

1054, 1021, 952, 839, 779, 734, 704, 686, 667, 627, 568, 555. HRMS

(ESI) m/z: calcd for [M − Cl]⁺C₄₆H₅₀ClN₆O₂Pd₂, 967.1765; found,

967.1766.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

benzo[d]imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}silver(I)

Dichloroargentate(1−) (6d-Ni-CyHex). Complex 6d-Ni-CyHex was

prepared according to the general procedure, and mononickel complex

5d-Ni-CyHex (341.02 mg, 0.4 mmol, 1.0 equiv) was used. Ag−

carbene complex 6d-Ni-CyHex (367.60 mg, 0,34 mmol, 86%) was

isolated as a red solid.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]palladium(II)}palladium(II) Di-

chloride (7b-Pd-CyHex). Complex 7b-Pd-CyHex was prepared

according to the general procedure, and Ag−carbene complex 6b-

Pd-CyHex (48.20 mg, 0.04 mmol, 1.0 equiv) was used. Bimetallic

complex 7b-Pd-CyHex (28.40 mg, 0.03 mmol, 65%, dr = >50:1) was

isolated as a yellow solid.

C₄₆H₅₂Ag₂Cl₂N₆NiO₂mol wt: 1066.28. Mp: 195.6−196.7 °C dec.

1

[α]²⁰= −226.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (300 MHz,

D

CDCl₃): δ 7.94−7.91 (m, 2 H, CH_Imid), 7.50 (s, 2 H, NCH), 7.41

(d, J = 2.5, 2 H, CH_Ar), 7.29−7.27 (m, 4 H, CH_Imid), 7.22−7.19 (m, 2

H, CH_Imid), 7.14 (d, J = 2.5, 2 H, CH_Ar), 5.31 (d, J = 14.0, 2 H,

C_ArCH₂), 5.25 (d, J = 14.0, 2 H, C_ArCH₂), 3.89 (s, 6 H, NCH₃), 3.14−

3.12 (m, 2 H, N(CH)_Ring), 2.51−2.48 (m, 2 H, (CH₂)_Ring), 1.96−1.94

(m, 2 H, (CH₂)_Ring), 1.42−1.32 (m, 4 H, (CH₂)_Ring), 1.19 (s, 18 H,

C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ 186.5, 159.0, 157.1, 136.7,

133.1, 132.8, 132.1, 128.8, 123.2, 123.1 (2×), 118.9, 112.3, 109.3, 69.2,

C₄₈H₅₂Cl₂N₆O₂Pd₂mol wt: 1028.71. Mp: >300 °C dec. [α]²⁰

=

D

−124.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂, main

isomer): δ 7.99 (d, J = 7.8, 4 H, CH_Ph), 7.76 (s, 2 H, NCH), 7.26−

7.23 (m, 2 H, CH_Ph), 7.22 (d, J = 2.5, 2 H, CH_Ar), 7.16−7.13 (m, 4 H,

CH_Ph, 2 H, CH_Ar), 6.97 (d, J = 1.9, 2 H, NCH_Imid), 6.52 (d, J = 1.9, 2

H, NCH_Imid), 4.90 (d, J = 14.4, 2 H, C_ArCH₂), 4.20 (d, J = 14.4, 2 H,

C_ArCH₂), 3.26−3.23 (m, 2 H, N(CH)_Ring), 2.64−2.60 (m, 2 H,

(CH₂)_Ring), 1.99−1.97 (m, 2 H, (CH₂)_Ring), 1.40−1.36 (m, 4 H,

(CH₂)_Ring), 1.33 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CD₂Cl₂,

main isomer): δ 156.2, 141.1, 139.8, 136.8, 134.2, 130.5, 129.2 (2×),

128.2, 127.7, 127.2 (2×), 123.2, 121.0, 120.1, 71.9, 34.0, 31.5 (3×),

46.6, 34.9, 32.7, 30.7 (3×), 27.9, 23.4. IR (solid): v 2947, 2860, 1618,

̃

1547, 1443, 1386, 1340, 1309, 1263, 1220, 1047, 807, 741, 553. HRMS

(ESI) m/z: calcd for [M − (Cl−Ag−Cl)]⁺C₄₆H₅₂AgN₆NiO₂,

887.2542; found, 887.2538.

29.1, 25.1. IR (solid): v 2949, 2859, 1618, 1537, 1498, 1449, 1426,

̃

General Procedure for the Synthesis of Bimetallic Salen Bis-

NHC Complexes 7-M¹. Pd₂(dba)₃(0.6 equiv) was added to a

solution of Ag−carbene complexes 6-M¹(1.0 equiv) in CH₂Cl₂(0.1

mmol in 20 mL), and the mixture was stirred for 24 h at room

temperature. The solvent was removed under reduced pressure, and

the residue was puriﬁed by ﬂash chromatography on silica gel (eluent

1/1 petroleum ether/ethyl acetate and 40/1 or 80/1 CH₂Cl₂/MeOH)

to isolate 7-M¹, which was dried in vacuo (0.1 mbar).

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)] palladium(II)}palladium(II) Di-

chloride (7a-Pd-CyHex). Complex 7a-Pd-CyHex was prepared

according to the general procedure, and Ag−carbene complex 6a-

Pd-CyHex (50.69 mg, 0.05 mmol, 1.0 equiv) was used. Bimetallic

complex 7a-Pd-CyHex (33.30 mg, 0.04 mmol, 73%, dr = 10:1) was

isolated as a yellow solid.

1394, 1364, 1326, 1267, 1248, 1214, 1095, 1033, 957, 836, 763, 735,

693, 560, 545. HRMS (ESI) m/z: calcd for [M − Cl]⁺

C₄₈H₅₂ClN₆O₂Pd₂, 993.1922; found, 993.1930.

{[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-

κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-imidazol-1-yl-2(3H)-

ylidene]6,6′-dimethyl-1,1′-biphenyl](2−)]palladium(II)}palladium(II)

Dichloride (7a-Pd-BiPh). Complex 7b-Pd-BiPh was prepared

according to the general procedure, and Ag−carbene complex 6b-

Pd-BiPh (30.90 mg, 0.03 mmol, 1.0 equiv) was used. Bimetallic

complex 7b-Pd-BiPh (8.60 mg, 0.01 mmol, 30%, dr = >50:1) was

isolated as an orange solid.

C₅₆H₅₄Cl₂N₆O₂Pd₂mol wt: 1126.81. Mp: >200 °C dec. [α]²⁰

=

D

−337.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CDCl₃): δ

8.00 (d, J = 7.2, 2 H, CH_Ph), 7.33−7.27 (m, 2 H, CH_BiPh, 2 H, CH_Ph, 2

H, NCH), 7.13−7.07 (m, 2 H, CH_BiPh, 4 H, CH_Ph, 2 H, CH_Ar), 6.99

(d, J = 2.5, 2 H, CH_Ar), 6.96 (d, J = 1.9, 2 H, NCH_Imid), 6.79 (d, J = 7.3,

2 H, CH_BiPh), 6.69 (d, J = 1.9, 2 H, NCH_Imid), 5.18 (d, J = 15.2, 2 H,

C_ArCH₂), 4.23 (d, J = 13.3, 2 H, C_ArCH₂), 1.99 (s, 6 H, C_BiPhCH₃),

1

C₃₈H₄₈Cl₂N₆O₂Pd₂mol wt: 904.57. Mp: 146.0−147.8 °C dec.

1

[α]²⁰= −82.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz,

D

CDCl₃, main isomer): δ 7.76 (s, 2 H, NCH), 7.51 (d, J = 2.5, 2 H,

124

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

1.22 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃): δ 163.6,

161.0, 160.5, 148.7, 140.2, 138.7, 137.5, 134.8, 130.1, 129.9, 129.31,

129.29, 128.7 (2×), 127.2, 126.9, 126.2 (2×), 122.7, 122.5, 122.0,

mg, 0.04 mmol, 1.0 equiv) was used. Bimetallic complex 7b-Ni-CyHex

(13.9 mg, 0.01 mmol, 37%, dr = 16:1) was isolated as an orange solid.

C₄₈H₅₂Cl₂N₆NiO₂Pd mol wt: 980.98. Mp: >300 °C dec. [α]²⁰

=

D

119.7, 53.5, 33.7, 31.2 (3×), 19.4. IR (solid): v 3055, 2956, 2220, 1615,

−412.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂, main

isomer): δ 7.85 (d, J = 7.6, 4 H, CH_Ph), 7.28 (s, 2 H, NCH), 7.16−

7.13 (m, 2 H, CH_Ph), 7.09 (d, J = 1.9, 2 H, NCH_Imid), 7.05−7.02 (m, 4

H, CH_Ph), 7.00 (d, J = 2.5, 2 H, CH_Ar), 6.85 (d, J = 1.9, 2 H, NCH_Imid),

6.65 (d, J = 2.5, 2 H, CH_Ar), 5.05 (d, J = 14.9, 2 H, C_ArCH₂), 4.10 (d, J

= 14.9, 2 H, C_ArCH₂), 2.74−2.72 (m, 2 H, N(CH)_Ring), 2.33−2.31 (m,

2 H, (CH₂)_Ring), 1.81−1.80 (m, 2 H, (CH₂)_Ring), 1.22 (s, 18 H,

C(CH₃)₃), 1.19−1.18 (m, 4 H, (CH₂)_Ring),. ¹³C NMR (125 MHz,

CD₂Cl₂, main isomer): δ 161.7, 160.9, 158.2, 140.7, 136.8, 133.7,

129.2 (2×), 129.0, 128.1, 126.7 (2×), 126.0, 123.6, 120.3, 120.2. IR

̃

1596, 1574, 1541, 1499, 1449, 1425, 1399, 1365, 1323, 1270, 1242,

1213, 1023, 957, 911, 764, 731, 695, 642, 556, 545. HRMS (ESI) m/z:

calcd for [M − 2Cl]²⁺C₅₆H₅₄N₆O₂Pd₂, 528.1197; found, 528.1180.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

benzo[d]imidazol-1-yl-2(3H)-ylidene]](2−)]palladium(II)}palladium-

(II) Dichloride (7d-Pd-CyHex). Complex 7d-Pd-CyHex was prepared

according to the general procedure, and Ag−carbene complex 6d-Pd-

CyHex (48.60 mg, 0.04 mmol, 1.0 equiv) was used. Bimetallic

complex 7d-Pd-CyHex (29.50 mg, 0.03 mmol, 67%, dr = 6:1) was

isolated as a yellow solid.

̃

(solid): ν = 2949, 2866, 1620, 1545, 1499, 1451, 1429, 1401, 1365,

1329, 1272, 1250, 1224, 1177, 1132, 1099, 1043, 957, 836, 763, 737,

693, 560, 547. HRMS (ESI) m/z: calcd for [M − Cl]⁺

C₄₈H₅₂ClN₆NiO₂Pd, 945.2218; found, 945.2224.

C₄₆H₅₂Cl₂N₆O₂Pd₂mol wt: 1004.69. Mp: >200 °C dec. [α]²⁰

=

D

−264.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CDCl₃, main

isomer): δ 7.73 (d, J = 2.5, 2 H, CH_Ar), 7.48 (br, 2 H, NCH), 7.18

(br, 2 H, CH_Ar), 7.11 (d, J = 8.1, 2 H, CH_Imid), 6.97 (t, J = 7.5, 2 H,

CH_Imid), 6.89 (d, J = 13.7, 2 H, C_ArCH₂), 6.78 (t, J = 7.5, 2 H, CH_Imid),

6.44 (d, J = 8.1, 2 H, CH_Imid), 5.37 (d, J = 13.7, 2 H, C_ArCH₂), 4.41 (s,

6 H, NCH₃), 2.83 (br, 2 H, N(CH)_Ring), 2.42−2.40 (m, 2 H,

(CH₂)_Ring), 1.82 (br, 2 H, (CH₂)_Ring), 1.40 (s, 18 H, C(CH₃)₃), 1.29−

1.14 (m, 4 H, (CH₂)_Ring). ¹³C NMR (125 MHz, CDCl₃, main isomer):

δ 175.1, 163.1, 155.1, 136.7, 135.7, 134.2, 134.1, 130.9, 124.8, 121.9 (2

× C), 120.2, 111.5, 109.9, 71.1, 54.4, 35.7, 33.8, 31.6 (3× C), 28.4,

{[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-

κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-imidazol-1-yl-2(3H)-

ylidene]-6,6′-dimethyl-1,1′-biphenyl](2−)]nickel(II)}palladium(II) Di-

chloride (7b-Ni-BiPh). Complex 7b-Ni-BiPh was prepared according

to the general procedure, and Ag−carbene complex 6b-Ni-BiPh

(24.70 mg, 0.02 mmol, 1.0 equiv) was used. Bimetallic complex 7b-Ni-

BiPh (12.80 mg, 0.01 mmol, 57%) was isolated as a red solid.

C₅₆H₅₄Cl₂N₆NiO₂Pd mol wt: 1079.09. Mp: >200 °C dec. [α]²⁰

=

D

1

−170.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (300 MHz, CDCl₃):

paramagnetic species, very broad signals. ¹³C NMR (125 MHz,

24.3. IR (solid): v 2948, 2863, 1617, 1538, 1443, 1391, 1364, 1339,

̃

CDCl ): paramagnetic species. IR (solid): v 2951, 1730, 1616, 1596,

̃

1307, 1266, 1242, 1199, 1128, 1095, 1039, 1015, 837, 810, 739, 577,

549. HRMS (ESI) m/z: calcd for [M − Cl]⁺C₄₈H₅₂ClN₆O₂Pd₂,

969.1922; found, 969.1901.

3

1543, 1498, 1453, 1362, 1303, 1273, 1239, 1213, 1103, 1042, 1019,

955, 881, 837, 815, 797, 759, 734, 693. HRMS (ESI) m/z: calcd for

[M − C₉H₈N₂Cl₂]⁺C₄₇H₄₆N₄O₂Pd₂, 432.0998; found, 432.0981. Anal.

Calcd for [C₅₆H₅₄Cl₂N₆NiO₂Pd+0.5C₅H₁₂]: C, 63.01; H, 5.42. Found:

C, 63.26; H, 5.49.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Dichloride

(7a-Ni-CyHex). Complex 7a-Ni-CyHex was prepared according to the

general procedure, and Ag−carbene complex 6a-Ni-CyHex (176.70

mg, 0.18 mmol, 1.0 equiv) was used. Bimetallic complex 7a-Ni-CyHex

(87.50 mg, 0.10 mmol, 56%, dr = 4:1) was isolated as a red solid.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-mesityl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Dichloride

(7c-Ni-CyHex). Complex 7c-Ni-CyHex was prepared according to the

general procedure, and Ag−carbene complex 6c-Ni-CyHex (134.00

mg, 0.11 mmol, 1.0 equiv) was used. Bimetallic complex 7c-Ni-CyHex

(30.0 mg, 0.03 mmol, 25%, dr = >50:1) was isolated as a orange solid.

C₃₈H₄₈Cl₂N₆NiO₂Pd mol wt: 856.85. Mp: >300 °C dec. [α]²⁰

=

D

−182.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CDCl₃, main

isomer): δ 7.41 (s, 2 H, NCH), 7.37 (d, J = 2.5, 2 H, CH_Ar), 7.15 (d,

J = 2.5, 2 H, CH_Ar), 6.79 (d, J = 1.9, 2 H, NCH_Imid), 6.40 (d, J = 1.9, 2

H, NCH_Imid), 4.99 (d, J = 12.5, 2 H, C_ArCH₂), 4.82 (d, J = 12.5, 2 H,

C_ArCH₂), 4.26 (s, 6 H, NCH₃), 2.88−2.87 (m, 2 H, N(CH)_Ring), 2.46−

2.44 (m, 2 H, (CH₂)_Ring), 1.94−1.93 (m, 2 H, (CH₂)_Ring), 1.32−1.30

(m, 4 H, (CH₂)_Ring), 1.28 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz,

CDCl₃, main isomer): δ 161.7, 158.1, 157.0, 137.0, 134.0, 129.3, 123.9,

121.3, 119.9, 119.6, 69.7, 51.6, 39.3, 33.8, 31.4 (3×), 28.7, 24.4. IR

C₅₄H₆₄Cl₂N₆NiO₂Pd mol wt: 1065.14. Mp: >200 °C dec. [α]²⁰

=

D

−326.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CDCl₃, main

isomer): δ 7.39 (s, 2 H, NCH), 7.37 (d, J = 2.5, 2 H, CH_Ar), 7.07 (d,

J = 1.9, 2 H, NCH_Imid), 7.01 (d, J = 2.5, 2 H, CH_Ar), 6.83 (d, J = 20.2, 4

H, CH_Mes), 6.66 (d, J = 1.9, 2 H, NCH_Imid), 6.12 (d, J = 14.9, 2 H,

C_ArCH₂), 5.99 (d, J = 14.9, 2 H, C_ArCH₂), 3.17−3.16 (m, 2 H,

N(CH)_Ring), 2.46 (s, 6 H, p-CH₃C_Mes), 2.39−1.37 (m, 2 H, (CH₂)_Ring),

2.00 (s, 6 H, o-CH₃C_Mes), 1.89 (s, 6 H, o-CH₃C_Mes), 1.88−1.87 (m, 2

H, (CH₂)_Ring), 1.31−1.29 (m, 4 H, (CH₂)_Ring), 1.24 (s, 18 H,

C(CH₃)₃). ¹³C NMR (125 MHz, CDCl₃, main isomer): δ 171.4,

161.3, 157.1, 137.1, 136.3, 136.0, 135.9, 131.1, 128.8, 128.5, 127.5,

127.2, 122.4, 119.9 (2×), 69.9, 49.3, 33.7, 31.5 (3×), 28.5, 24.5, 21.3,

(solid): v 2947, 2862, 1619, 1548, 1459, 1438, 1340, 1272, 1221, 1201,

̃

838, 739, 685, 665, 617, 592, 560. HRMS (ESI) m/z: calcd for [M −

Cl]⁺C₃₈H₄₈ClN₆NiO₂Pd, 821.1902; found, 821.1905.

{[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-

κO)-3,1-phenylene]methylene]bis[1-methyl-1H-imidazol-1-yl-2(3H)-

ylidene]6,6′-dimethyl-1,1′-biphenyl](2−)]nickel(II)}palladium(II) Di-

chloride (7a-Ni-BiPh). Complex 7a-Ni-BiPh was prepared according

to the general procedur,e and Ag−carbene complex 6a-Ni-BiPh

(35.00 mg, 0.03 mmol, 1.0 equiv) was used. Bimetallic complex 7a-Ni-

BiPh (6.70 mg, 0.01 mmol, 21%) was isolated as an brown solid.

18.9, 18.7. IR (solid): v 2953, 2362, 1803, 1619, 1542, 1448, 1412,

̃

1392, 1363, 1339, 1233, 1189, 1162, 1073, 1044, 903, 849, 726, 650.

HRMS (ESI) m/z: calcd for [M + Na]⁺C₅₄H₆₄Cl₂N₆NaNiO₂Pd,

1087.2742; found, 1087.2738.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

benzo[d]imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II)

Dichloride (7d-Ni-CyHex). Complex 7d-Ni-CyHex was prepared

according to the general procedure, and Ag−carbene complex 6d-Ni-

CyHex (381.00 mg, 0.36 mmol, 1.0 equiv) was used. Bimetallic

complex 7d-Ni-CyHex (173.2 mg, 0.18 mmol, 51%, dr = 4:1) was

isolated as an orange solid.

C₄₆H₅₀Cl₂N₆NiO₂Pd mol wt: 954.95. Mp: 172.0−177.0 °C dec.

1

[α]²⁰= −167.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (300 MHz,

D

CDCl₃): paramagnetic species, very broad signals. ¹³C NMR (125

MHz, CDCl ): paramagnetic species. IR (solid): v 2954, 2866, 1618,

̃

3

1571, 1537, 1455, 1394, 1364, 1271, 1234, 1213, 1162, 1108, 1091,

1055, 1020, 972, 948, 883, 836, 802, 775, 735, 699, 674, 619. HRMS

(ESI) m/z: calcd for [M − Cl]⁺C₄₆H₅₀ClN₆NiO₂Pd: 919.2061; found,

919.2063. Anal. Calcd for [C₄₆H₅₀Cl₂N₆NiO₂Pd+CH₃OH]: C, 57.19;

H, 5.51. Found: C, 57.06; H, 5.89.

C₄₆H₅₂Cl₂N₆NiO₂Pd mol wt: 956.96. Mp: >300 °C dec. [α]²⁰

=

D

−370.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂, main

isomer): δ 7.63 (d, J = 2.5, 2 H, CH_Ar), 7.38 (d, J = 8.3, 2 H, CH_Imid),

7.23 (s, 2 H, NCH), 7.28−7.22 (m, 2 H, CH_Imid), 7.15 (d, J = 2.5, 2

H, CH_Ar), 6.96 (t, J = 7.9, 2 H, CH_Imid), 6.47 (d, J = 2.5, 2 H, CH_Ar),

6.31 (d, J = 13.5, 2 H, C_ArCH₂), 5.31 (d, J = 13.5, 2 H, C_ArCH₂), 4.42

(s, 6 H, NCH₃), 2.61−2.59 (m, 2 H, N(CH)_Ring), 2.27−2.23 (m, 2 H,

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Dichloride

(7b-Ni-CyHex). Complex 7b-Ni-CyHex was prepared according to the

general procedure, and Ag−carbene complex 6b-Ni-CyHex (41.50

125

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

(CH₂)_Ring), 1.79−1.78 (m, 2 H, (CH₂)_Ring), 1.39 (s, 18 H, C(CH₃)₃),

1.14−1.12 (m, 4 H, (CH₂)_Ring),. ¹³C NMR (125 MHz, CD₂Cl₂, main

isomer): δ 174.1, 162.2, 157.7, 137.4, 136.0, 134.9, 134.1, 134.0, 130.0,

123.8, 122.8, 122.7, 119.8, 112.3, 110.4, 69.6, 36.2, 34.0, 31.6 (3× C),

122.5, 121.7, 70.5, 50.8, 37.6, 34.3, 31.2 (3×), 29.6, 24.3. IR (solid): v

3626, 3140, 2952, 1627, 1568, 1460, 1365, 1280, 1249, 1229, 1193,

1031, 870, 833, 795, 732, 693, 670, 649, 607, 579. HRMS (ESI) m/z:

calcd for [M − 2BF₄]²⁺C₃₈H₄₈N₆NiO₂Pd, 393.1106; found, 393.1103.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO,κO)-3,1-phenylene]methylene]bis[1-methyl-

1H-imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Ditri-

ﬂate (13a-Ni-CyHex-OTf). For the anion exchange of complex 7a-

Ni-CyHex (15.00 mg, 0.02 mmol, 1.0 equiv) according to the general

procedure, AgOTf (9.00 mg, 0.04 mmol, 2.0 equiv) was used.

Activated complex 13a-Ni-CyHex-OTf (17.0 mg, 0.02 mmol, 89%)

was isolated as a green solid.

̃

29.0, 24.7. IR (solid): v 2949, 2861, 1620, 1548, 1457, 1393, 1364,

̃

1341, 1274, 1243, 1224, 1175, 119, 1097, 1054, 1018, 838, 810, 739,

684, 595, 578, 551. HRMS (ESI) m/z: calcd for [M − Cl]⁺

C₄₈H₅₂ClN₆NiO₂Pd, 921.2217; found, 921.2200.

General Procedure for the Anion Exchange in the Bimetallic

salen Bis-NHC Complexes 7-M¹. To a solution of the

corresponding bimetallic salen bis-NHC complex 7-M¹(1.0 equiv)

in CH₂Cl₂(0.1 mmol in 20 mL) was added the corresponding silver

salt (2.0 equiv). The resulting suspension was stirred for about 20 min

at room temperature until precipitation of AgCl was visible.

Subsequently the mixture was ﬁltered through a pad of Celite, the

solvent was removed under reduced pressure, and the pure complexes

13-M¹were dried in vacuo (0.1 mbar).

C₄₀H₄₈F₆N₆NiO₈PdS₂mol wt: 1084.08. Mp: >200 °C dec. [α]²⁰

=

D

−739.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CD₂Cl₂): δ

13.50 (br, 2 H, NCH), 7.71 (d, J = 2.5, 2 H, CH_Ar), 7.41 (d, J = 1.9,

2 H, NCH_Imid), 7.34 (d, J = 2.5, 2 H, CH_Ar), 7.01 (d, J = 1.9, 2 H,

NCH_Imid), 6.55 (d, J = 14.3, 2 H, C_ArCH₂), 5.07 (d, J = 14.3, 2 H,

C_ArCH₂), 3.59 (br, 2 H, N(CH)_Ring), 3.17 (s, 6 H, NCH₃), 2.44−2.42

(m, 2 H, (CH₂)_Ring), 2.05−2.04 (m, 2 H, (CH₂)_Ring), 1.31−1.25 (m, 4

H, (CH₂)_Ring), 1.22 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz,

CD₂Cl₂): δ 163.2, 154.7, 144.2, 143.2, 136.3, 132.5, 126.2, 122.5, 67.3,

1

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO,κO)-3,1-phenylene]methylene]bis[1-methyl-

1H-imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Bis-

(hexaﬂuorophosphate) (13a-Ni-CyHex-PF₆). For the anion exchange

of complex 7a-Ni-CyHex (75.50 mg, 0.09 mmol, 1.0 equiv) according

to the general procedure, AgPF₆(42.80 mg, 0.17 mmol, 2.0 equiv) was

used. Activated complex 13a-Ni-CyHex-PF₆(69.3 mg, 0.06 mmol,

76%) was isolated as a green solid.

51.0, 37.7, 34.3, 31.5, 31.3 (3×), 24.4. IR (solid): v 3511, 3132, 2951,

̃

1623, 1568, 1468, 1409, 1362, 1245, 1225, 1191, 1150, 1052, 1030,

937, 873, 834, 796, 756, 734, 697, 638, 622. HRMS (ESI) m/z: calcd

for [M − OTf]⁺C₃₉H₄₈F₃N₆NiO₅PdS, 935.1737; found, 935.1710.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Ditosylate

(12a-Ni-CyHex-OTs). For the anion exchange of complex 7a-Ni-

CyHex (15.00 mg, 0.02 mmol, 1.0 equiv) according to the general

procedure, AgOTs (9.77 mg, 0.04 mmol, 2.0 equiv) was used.

Activated complex 12a-Ni-CyHex-OTs (18.5 mg, 0.02 mmol, 93%, dr

= 3.1:1) was isolated as a yellow solid.

C₃₈H₄₈F₁₂N₆NiO₂P₂Pd mol wt: 1075.87. Mp: >300 °C dec. [α]²⁰

D

= −1230.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂):

δ 7.55 (d, J = 2.5, 2 H, CH_Ar), 7.43 (br, 2 H, NCH), 7.36−7.35 (m,

4 H, CH_Ar, NCH_Imid), 7.05 (d, J = 1.9, 2 H, NCH_Imid), 6.48 (d, J =

14.6, 2 H, C_ArCH₂), 5.05 (d, J = 14.6, 2 H, C_ArCH₂), 3.21 (s, 6 H,

NCH₃), 3.09−3.07 (m, 2 H, N(CH)_Ring), 2.49−2.48 (m, 2 H,

(CH₂)_Ring), 1.90−1.89 (m, 2 H, (CH₂)_Ring), 1.32−1.30 (m, 4 H,

(CH₂)_Ring), 1.30 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CD₂Cl₂):

δ 161.8, 154.4, 144.0, 142.8, 136.4, 133.5, 126.2, 124.0, 122.3, 121.7,

C₅₂H₆₂N₆NiO₈PdS₂mol wt: 1128.33. Mp: >200 °C dec. [α]²⁰

=

D

−145.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂, main

isomer): δ 7.52 (br, 4 H, CH_OTs), 7.37 (d, J = 2.5, 2 H, CH_Ar), 7.35 (s,

2 H, NCH), 7.12 (d, J = 2.5, 2 H, CH_Ar), 7.05 (d, J = 6.8, 4 H,

CH_OTs), 6.80 (br, 2 H, NCH_Imid), 6.40 (d, J = 1.9, 2 H, NCH_Imid), 4.75

(d, J = 12.9, 2 H, C_ArCH₂), 4.69 (d, J = 12.9, 2 H, C_ArCH₂), 4.09 (s, 6

H, NCH₃), 2.79−2.77 (br, 2 H, N(CH)_Ring), 2.33−2.31 (m, 2 H,

(CH₂)_Ring), 2.27 (s, 6 H, C_OTsCH₃), 1.82−1.81 (m, 2 H, (CH₂)_Ring),

1.22 (s, 18 H, C(CH₃)₃), 1.20−1.18 (m, 4 H, (CH₂)_Ring). ¹³C NMR

(125 MHz, CD₂Cl₂, main isomer): δ 161.8, 157.6, 148.0, 140.4, 137.4,

134.9, 130.0, 129.0 (2×), 126.5 (2×), 123.6, 122.0, 120.9, 120.0, 119.7,

70.6, 51.0, 37.7, 34.2, 31.2 (3×), 29.6, 24.3. IR (solid): v 3652, 3184,

̃

2946, 2864, 1645, 1571, 1462, 1396, 1364, 1305, 1277, 1248, 1230,

1194, 1137, 1108, 1088, 1049, 931, 826, 793, 778, 736, 692, 669, 648,

627, 606, 580, 555. HRMS (ESI) m/z: calcd for [M − PF₆− 2F₂]⁺

C₃₈H₄₈F₂N₆NiO₂PPd, 855.2901; found, 855.2911.

{[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-

κO,κO)-3,1-phenylene]methylene]bis[1-methyl-1H-imidazol-1-yl-

2(3H)-ylidene]-6,6′-dimethyl-1,1′-biphenyl] (2−)]nickel(II)}-

palladium(II) Bis(hexaﬂuorophosphate) (13a-Ni-BiPh-PF₆). For the

anion exchange of complex 7a-Ni-BiPh (16.80 mg, 0.02 mmol, 1.0

equiv) according to the general procedure, AgPF₆(8.90 mg, 0.04

mmol, 2.0 equiv) was used. Activated complex 13a-Ni-BiPh-PF₆(16.1

mg, 0.01 mmol, 78%) was isolated as a brown solid.

70.2, 52.1, 38.8, 34.1, 31.5 (3×), 29.0, 24.7, 21.5. IR (solid): v 2948,

̃

2863, 1618, 1549, 1461, 1440, 1406, 1364, 1338, 1253, 1221, 1202,

1156, 1106, 1057, 1030, 994, 868, 839, 816, 736, 708, 679. HRMS

(ESI) m/z: calcd for [M − OTs]⁺C₄₅H₅₅N₆NiO₅PdS, 957.2334;

found, 957.2312.

C₄₆H₅₀F₁₂N₆NiO₂P₂Pd mol wt: 1173.97. Mp: 162.0−165.0 °C dec.

1

[α]²⁰= −151.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (300 MHz,

D

CDCl₃): paramagnetic species, very broad signals. ¹³C NMR (125

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO,κO)-3,1-phenylene]methylene]bis[1-methyl-

1H-imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Bis-

(heptaﬂuorobutyrate) (12a-Ni-CyHex-O₂CC₃F₇). For the anion

exchange of complex 7a-Ni-CyHex (15.00 mg, 0.02 mmol, 1.0

equiv) according to the general procedure, AgO₂CC₃F₇(11.25 mg,

0.04 mmol, 2.0 equiv) was used. Activated complex 12a-Ni-CyHex-

O₂CC₃F₇(20.2 mg, 0.02 mmol, 95%, dr = 2.9:1) was isolated as a red

solid.

MHz, CDCl ): paramagnetic species. IR (solid): v 2955, 2923, 2855,

̃

3

1720, 1618, 1546, 1456, 1366, 1273, 1217, 1161, 1108, 1024, 830, 738,

695. HRMS (ESI) m/z: calcd for [M − PF₆]⁺C₄₆H₅₀F₆N₆NiO₂PPd,

1029.2018; found, 1029.2009.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO,κO)-3,1-phenylene]methylene]bis[1-methyl-

1H-imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Bis-

(tetraﬂuoroborate) (13a-Ni-CyHex-BF₄). For the anion exchange of

complex 7a-Ni-CyHex (15.00 mg, 0.02 mmol, 1.0 equiv) according to

the general procedure, AgBF₄(6.82 mg, 0.04 mmol, 2.0 equiv) was

used. Activated complex 13a-Ni-CyHex-BF₄(15.8 mg, 0.02 mmol,

94%) was isolated as a green solid.

C₄₆H₄₈F₁₄N₆NiO₆Pd mol wt: 1212.00. Mp: >200 °C dec. [α]²⁰

=

D

−189.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂, main

isomer): δ 7.54 (d, J = 2.5, 2 H, CH_Ar), 7.43 (s, 2 H, NCH), 7.20 (d,

J = 2.5, 2 H, CH_Ar), 6.87 (d, J = 1.9, 2 H, NCH_Imid), 6.50 (d, J = 1.9, 2

H, NCH_Imid), 5.05 (d, J = 13.1, 2 H, C_ArCH₂), 5.00 (d, J = 13.1, 2 H,

C_ArCH₂), 4.18 (s, 6 H, NCH₃), 2.88−2.87 (m, 2 H, N(CH)_Ring), 2.42−

2.40 (m, 2 H, (CH₂)_Ring), 1.91−1.90 (m, 2 H, (CH₂)_Ring), 1.30 (s, 18

H, C(CH₃)₃), 1.30−1.26 (m, 4 H, (CH₂)_Ring). ¹³C NMR (125 MHz,

CD₂Cl₂, main isomer): δ 160.7, 160.5, 156.5, 152.1, 136.3, 133.9,

122.7, 120.3, 119.3, 118.8, 69.1, 51.2, 37.0, 32.9, 30.3 (3×), 27.9, 23.6.

C₃₈H₄₈B₂F₈N₆NiO₂Pd mol wt: 959.55. Mp: >200 °C dec. [α]²⁰

=

D

−955.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CD₂Cl₂): δ

7.57 (d, J = 2.5, 2 H, CH_Ar), 7.49 (br, 2 H, NCH), 7.40 (d, J = 1.9, 2

H, NCH_Imid), 7.29 (d, J = 2.5, 2 H, CH_Ar), 6.99 (d, J = 1.9, 2 H,

NCH_Imid), 6.37 (d, J = 14.6, 2 H, C_ArCH₂), 5.08 (d, J = 14.6, 2 H,

C_ArCH₂), 3.11 (s, 6 H, NCH₃), 3.03−3.01 (m, 2 H, N(CH)_Ring), 2.43−

2.42 (m, 2 H, (CH₂)_Ring), 1.81−1.80 (m, 2 H, (CH₂)_Ring), 1.23−1.22

(m, 4 H, (CH₂)_Ring), 1.21 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz,

CD₂Cl₂): δ 162.0, 154.4, 144.0, 142.6, 136.7, 133.4, 126.2, 124.2,

1

IR (solid): v 2953, 1686, 1620, 1550, 1462, 1441, 1367, 1329, 1272,

̃

1201, 1159, 1114, 1077, 962, 926, 839, 811, 719, 687, 650, 595. HRMS

126

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

(ESI) m/z: calcd for [M − O₂CC₃F₇]⁺C₄₂H₄₈F₇N₆NiO₄Pd, 999.2005;

found, 999.1998.

C₄₈H₅₂B₂F₈N₆NiO₂Pd mol wt: 1083.69. Mp: >200 °C dec. [α]²⁰

=

D

−514.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CD₂Cl₂): δ

7.57−7.52 (m, 6 H, CH_Ph, 2 H, NCH), 7.44−7.42 (m, 4 H, CH_Ph, 2

H, CH_Ar), 7.29 (d, 2 H, CH_Ar), 6.99 (d, J = 1.9, 2 H, NCH_Imid), 6.92

(d, J = 1.9, 2 H, NCH_Imid), 5.76 (d, J = 14.6, 2 H, C_ArCH₂), 4.41 (d, J =

14.6, 2 H, C_ArCH₂), 3.07−3.05 (m, 2 H, N(CH)_Ring), 2.45−2.43 (m, 2

H, (CH₂)_Ring), 1.81−1.80 (m, 2 H, (CH₂)_Ring), 1.25−1.24 (m, 4 H,

(CH₂)_Ring), 1.17 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CD₂Cl₂):

δ 173.7, 161.9, 154.5, 144.5, 143.9, 138.1, 136.7, 133.5, 130.8, 130.6

(2×), 125.3 (2×), 124.3, 124.0, 122.3, 121.7, 70.5, 50.6, 34.2, 31.1

1

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Diacetate

(12a-Ni-CyHex-OAc). For the anion exchange of complex 7a-Ni-

CyHex (14.30 mg, 0.02 mmol, 1.0 equiv) according to the general

procedure, AgOAc (5.57 mg, 0.03 mmol, 2.0 equiv) was used.

Activated complex 12a-Ni-CyHex-OAc (15.1 mg, 0.02 mmol, 100%,

dr = 3.4:1) was isolated as an orange solid.

C₄₂H₅₄N₆NiO₆Pd mol wt: 904.03. Mp: >200 °C dec. [α]²⁰

=

D

(3×), 29.6, 24.3. IR (solid): v 3539, 3142, 2953, 2866, 1630, 1596,

̃

−107.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CDCl₃, main

isomer): δ 7.53 (d, J = 2.5, 2 H, CH_Ar), 7.38 (s, 2 H, NCH), 7.09 (d,

J = 2.5, 2 H, CH_Ar), 6.71 (d, J = 1.9, 2 H, NCH_Imid), 6.38 (d, J = 1.9, 2

H, NCH_Imid), 5.04 (d, J = 5.5, 2 H, C_ArCH₂), 5.00 (d, J = 5.5, 2 H,

C_ArCH₂), 4.20 (s, 6 H, NCH₃), 2.86−2.84 (m, 2 H, N(CH)_Ring), 2.44−

2.41 (m, 2 H, (CH₂)_Ring), 1.93−1.91 (m, 2 H, (CH₂)_Ring), 1.90 (s,

O₂CCH₃), 1.31−1.29 (m, 4 H, (CH₂)_Ring), 1.26 (s, 18 H, C(CH₃)₃).

¹³C NMR (125 MHz, CDCl₃, main isomer): δ 177.4, 162.0, 157.5,

156.9, 136.9, 134.8, 128.8, 124.5, 120.4, 119.5, 119.3, 69.7, 51.6, 38.0,

1567, 1498, 1460, 1431, 196, 1363, 1304, 1281, 1253, 1229, 1190,

1023, 870, 833, 794, 764, 729, 693, 645, 605, 583, 551. HRMS (ESI)

m/z: calcd for [M − BF₄]⁺C₄₈H₅₂BF₄N₆NiO₂Pd, 997.2569; found,

997.2569.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO,κO)-3,1-phenylene]methylene]bis[1-phenyl-

1H-imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Ditri-

ﬂate (13b-Ni-CyHex-OTf). For the anion exchange of complex 7b-

Ni-CyHex (15.00 mg, 0.02 mmol, 1.0 equiv) according to the general

procedure, AgOTf (7.86 mg, 0.03 mmol, 2.0 equiv) was used.

Activated complex 13b-Ni-CyHex-OTf (13.7 mg, 0.01 mmol, 74%)

was isolated as a green solid.

33.8, 34.4 (3×), 28.7, 24.4, 23.8. IR (solid): v 2949, 2863, 1618, 1580,

̃

1546, 1460, 1438, 1365, 1326, 1273, 1250, 1222, 1200, 1126, 1105,

1044, 1015, 952, 924, 869, 839, 793, 736, 689, 677, 617, 594, 574, 559.

HRMS (ESI) m/z: calcd for [M − 2OAc + OEt]⁺C₄₀H₅₃N₆NiO₃Pd,

832.2636; found, 832.2087.

C₅₀H₅₂F₆N₆NiO₈PdS₂mol wt: 1208.22. Mp: >200 °C dec. [α]²⁰

=

D

−561.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CD₂Cl₂): δ

15.01 (br, 2 H, NCH), 7.65 (d, 2 H, CH_Ar), 7.58−7.48 (m, 10 H,

CH_Ph,), 7.36 (d, 2 H, CH_Ar), 7.00 (d, J = 1.9, 2 H, NCH_Imid), 6.94 (d, J

= 1.9, 2 H, NCH_Imid), 5.97 (d, J = 14.5, 2 H, C_ArCH₂), 4.42 (d, J =

14.5, 2 H, C_ArCH₂), 3.84−3.83 (m, 2 H, N(CH)_Ring), 2.47−2.44 (m, 2

H, (CH₂)_Ring), 2.13−2.10 (m, 2 H, (CH₂)_Ring), 1.33−1.25 (m, 4 H,

(CH₂)_Ring), 1.18 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz, CD₂Cl₂):

δ 163.5, 154.9, 145.2, 144.3, 138.2, 136.2, 134.5, 132.0, 130.63, 130.55

(2×), 126.0, 125.4 (2×), 124.3, 122.3, 65.4, 50.8, 34.2, 32.6, 31.3 (3×),

1

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO,κO)-3,1-phenylene]methylene]bis[1-phenyl-

1H-imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Bis-

(hexaﬂuorophosphate) (13b-Ni-CyHex-PF₆). For the anion exchange

of complex 7b-Ni-CyHex (48.30 mg, 0.05 mmol, 1.0 equiv) according

to the general procedure, AgPF₆(24.90 mg, 0.10 mmol, 2.0 equiv) was

used. Activated complex 13b-Ni-CyHex-PF₆(45.7 mg, 0.04 mmol,

77%) was isolated as a green solid.

C₄₈H₅₂F₁₂N₆NiO₂P₂Pd mol wt: 1200.01. Mp: >200 °C dec. [α]²⁰

24.6. IR (solid): v 2953, 2867, 1630, 1597, 1567, 1499, 1460, 1430,

̃

D

= −606.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂): δ

7.66−7.59 (m, 6 H, CH_Ph), 7.52−7.49 (m, 4 H, CH_Ph, 2 H, NCH),

7.43 (br, 2 H, CH_Ar), 7.35 (d, J = 2.5, 2 H, CH_Ar), 6.98 (d, J = 1.9, 2 H,

NCH_Imid), 6.93 (d, J = 1.9, 2 H, NCH_Imid), 5.89 (d, J = 14.5, 2 H,

C_ArCH₂), 4.39 (d, J = 14.5, 2 H, C_ArCH₂), 3.15 (br, 2 H, N(CH)_Ring),

2.50−2.47 (m, 2 H, (CH₂)_Ring), 1.91 (br, 2 H, (CH₂)_Ring), 1.35−1.29

(m, 4 H, (CH₂)_Ring), 1.25 (s, 18 H, C(CH₃)₃). ¹³C NMR (125 MHz,

CD₂Cl₂): δ 161.8, 154.4, 144.8, 143.8, 138.1, 136.3, 133.4, 130.7 (2×),

130.6 (2×), 125.3 (2×), 124.3, 121.9, 70.3, 50.8, 34.3, 31.1 (3×), 29.7,

1364, 1245, 1153, 1026, 834, 794, 758, 730, 693, 635, 573, 551. HRMS

(ESI) m/z: calcd for [M − 2OTf]²⁺C₄₈H₅₂N₆NiO₂Pd, 455.1264;

found, 455.1276.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Bis-

(heptaﬂuorobutyrate) (12b-Ni-CyHex-O₂CC₃F₇). For the anion

exchange of complex 7b-Ni-CyHex (15.00 mg, 0.02 mmol, 1.0

equiv) according to the general procedure, AgO₂CC₃F₇(9.81 mg, 0.03

mmol, 2.0 equiv) was used. Activated complex 12b-Ni-CyHex-

O₂CC₃F₇(13.8 mg, 0.01 mmol, 68%, dr = 12:1) was isolated as a

yellow solid.

24.3. IR (solid): v 2951, 2867, 1630, 1597, 1568, 1498, 1461, 1431,

̃

1362, 1304, 1279, 1252, 1229, 1188, 1107, 1076, 1047, 826, 793, 767,

729, 692. HRMS (ESI) m/z: calcd for [M − PF₆]⁺

C₄₈H₅₂F₆N₆NiO₂PPd, 1055.2175; found, 1055.2171.

C₅₆H₅₂F₁₄N₆NiO₆Pd mol wt: 1336.14. Mp: >200 °C dec. [α]²⁰

=

D

−230.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂, main

isomer): δ 7.61−7.58 (m, 4 H, CH_Ph), 7.28 (s, 2 H, NCH), 7.26−

7.23 (m, 2 H, CH_Ph), 7.17−7.11 (m, 4 H, CH_Ph), 7.09 (d, J = 2.5, 2 H,

CH_Ar), 7.00−6.98 (m, 4 H, NCH_Imid), 6.65 (d, J = 2.5, 2 H, CH_Ar),

4.98 (d, J = 15.9, 2 H, C_ArCH₂), 4.27 (d, J = 15.9, 2 H, C_ArCH₂), 2.73−

2.70 (m, 2 H, N(CH)_Ring), 2.33−2.31 (m, 2 H, (CH₂)_Ring), 1.82−1.80

(m, 2 H, (CH₂)_Ring), 1.22 (s, 18 H, C(CH₃)₃), 1.20−1.18 (m, 4 H,

(CH₂)_Ring). ¹³C NMR (125 MHz, CD₂Cl₂, main isomer): δ 161.8,

161.4, 158.1, 154.5, 140.3, 136.9, 134.2, 129.7 (2×), 128.9, 128.5,

125.9 (2×), 125.8, 123.0, 120.5, 120.2, 69.6, 54.4, 23.9, 31.4 (3×),

{[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-

κO,κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-imidazol-1-yl-

2(3H)-ylidene]6,6′-dimethyl-1,1′-biphenyl] (2−)]nickel(II)}-

palladium(II) Bis(hexaﬂuorophosphate) (13b-Ni-BiPh-PF₆). For the

anion exchange of complex 7b-Ni-BiPh (24.00 mg, 0.02 mmol, 1.0

equiv) according to the general procedure, AgPF₆(11.25 mg, 0.04

mmol, 2.0 equiv) was used. Activated complex 13b-Ni-BiPh-PF₆(26.6

mg, 0.02 mmol, 92%) was isolated as a brown solid.

C₅₆H₅₄F₁₂N₆NiO₂P₂Pd mol wt: 1298.11. Mp: 178.0−181.0 °C dec.

1

[α]²⁰= −57.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (300 MHz,

D

CDCl₃): paramagnetic species, very broad signals. ¹³C NMR (125

29.4, 24.7. IR (solid): v 2955, 2868, 1695, 1620, 1546, 1499, 1453,

̃

MHz, CDCl ): paramagnetic species. IR (solid): v 3458, 3148, 2958,

̃

1431, 1367, 1327, 1272, 1223, 1203, 1160, 1114, 1076, 962, 926, 870,

837, 811, 763, 721, 694, 646, 614, 603, 574, 563, 548. HRMS (ESI) m/

z: calcd for [M − O₂CC₃F₇]⁺C₅₂H₅₂F₇N₆NiO₄Pd, 1123.2321; found,

1123.2327.

3

1620, 1598, 1522, 1498, 1461, 1366, 1275, 1220, 1135, 1071, 834, 757,

737, 691, 556. HRMS (ESI) m/z: calcd for [M − 2PF₆]²⁺

C₅₆H₅₄N₆NiO₂Pd, 504.1344; found, 504.1347.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO,κO)-3,1-phenylene]methylene]bis[1-phenyl-

1H-imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Bis-

(tetraﬂuoroborate) (13b-Ni-CyHex-BF₄). For the anion exchange of

complex 7b-Ni-CyHex (15.00 mg, 0.02 mmol, 1.0 equiv) according to

the general procedure, AgBF₄(5.95 mg, 0.03 mmol, 2.0 equiv) was

used. Activated complex 13b-Ni-CyHex-BF₄(15.7 mg, 0.01 mmol,

95%) was isolated as a green solid.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Diacetate

(12b-Ni-CyHex-OAc). For the anion exchange of complex 7b-Ni-

CyHex (15.00 mg, 0.02 mmol, 1.0 equiv) according to the general

procedure, AgOAc (5.10 mg, 0.03 mmol, 2.0 equiv) was used.

Activated complex 12b-Ni-CyHex-OAc (15.5 mg, 0.02 mmol, 99%, dr

= 11:1) was isolated as an orange solid.

127

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

C₅₂H₅₈N₆NiO₆Pd mol wt: 1028.17. Mp: >200 °C dec. [α]²⁰

=

C₄₆H₅₂F₁₂N₆NiO₂P₂Pd mol wt: 1175.99. Mp: >250 °C dec. [α]²⁰

D

−309.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂, main

isomer): δ 7.69−7.67 (m, 4 H, CH_Ph), 7.28 (s, 2 H, NCH), 7.25−

7.20 (m, 2 H, CH_Ph), 7.16−7.11 (m, 4 H, CH_Ph), 7.04 (d, J = 2.5, 2 H,

CH_Ar), 7.00−6.98 (m, 4 H, NCH_Imid), 6.58 (d, J = 2.5, 2 H, CH_Ar),

5.06 (d, J = 15.5, 2 H, C_ArCH₂), 4.31 (d, J = 15.5, 2 H, C_ArCH₂), 2.74−

2.72 (m, 2 H, N(CH)_Ring), 2.33−2.31 (m, 2 H, (CH₂)_Ring), 1.82−1.80

(m, 2 H, (CH₂)_Ring), 1.70 (s, 6 H, O₂CCH₃), 1.20 (s, 18 H, C(CH₃)₃),

1.20−1.18 (m, 4 H, (CH₂)_Ring). ¹³C NMR (125 MHz, CD₂Cl₂, main

isomer): δ 177.9, 163.5, 161.5, 159.5, 142.3, 138.3, 135.8, 130.9 (2×),

130.1, 129.6, 127.8, 127.6 (2×), 123.7, 121.6, 121.5, 71.1, 55.9, 35.4,

= −354.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂): δ

7.81 (d, J = 9.3, 2 H, CH_Imid), 7.58 (d, J = 2.5, 2 H, CH_Ar), 7.51−7.47

(m, 2 H, CH_Imid), 7.40−7.36 (m, 4 H, CH_Imid), 7.33 (s, 2 H, NCH),

7.28 (d, J = 2.5, 2 H, NCH_Ar), 6.77 (d, J = 15.2, 2 H, C_ArCH₂), 5.52 (d,

J = 15.2, 2 H, C_ArCH₂), 3.43 (s, 6 H, NCH₃), 3.02−3.00 (m, 2 H,

N(CH)_Ring), 2.41−2.40 (m, 2 H, (CH₂)_Ring), 1.81−1.80 (m, 2 H,

(CH₂)_Ring), 1.24−1.23 (m, 4 H, (CH₂)_Ring), 1.20 (s, 18 H, C(CH₃)₃).

¹³C NMR (125 MHz, CD₂Cl₂): δ 161.8, 154.4, 154.3, 143.7, 136.5,

135.5, 133.6, 132.4, 126.0, 125.8, 123.3, 121.9, 112.3, 111.4, 70.5, 48.0,

34.9, 34.2, 31.1 (3×), 29.6, 24.2. IR (solid): v 2957, 1633, 1567, 1463,

̃

32.9 (3×), 30.8, 26.2, 25.7. IR (solid): v 2949, 2862, 1620, 1600, 1545,

̃

1411, 1365, 1345, 1308, 1280, 1249, 1230, 1108, 1052, 954, 874, 831,

746, 711, 677, 604, 556. HRMS (ESI) m/z: calcd for [M − PF₆]⁺

C₄₆H₅₂F₆N₆NiO₂PPd, 1031.2174; found, 1031.2164.

1499, 1451, 1428, 1418, 1366, 1325, 1272, 1250, 1223, 1200, 1105,

1039, 960, 922, 868, 837, 763, 736, 693, 677, 647, 631, 547. HRMS

(ESI) m/z: calcd for [M − 2OAc + OEt]⁺C₅₀H₅₇N₆NiO₃Pd,

955.2874; found, 955.2438.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO,κO)-3,1-phenylene]methylene]bis[1-methyl-

1H-benzo[d]imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium-

(II) Bis(tetraﬂuoroborate) (13d-Ni-CyHex-BF₄). For the anion

exchange of complex 7d-Ni-CyHex (15.00 mg, 0.02 mmol, 1.0

equiv) according to the general procedure, AgBF₄(6.10 mg, 0.03

mmol, 2.0 equiv) was used. Activated complex 13d-Ni-CyHex-BF₄

(15.50 mg, 0.02 mmol, 93%) was isolated as a green solid.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO,κO)-3,1-phenylene]methylene]bis[1-mesityl-

1H-imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Bis-

(hexaﬂuorophosphate) (13c-Ni-CyHex-PF₆). For the anion exchange

of complex 7c-Ni-CyHex (20.00 mg, 0.02 mmol, 1.0 equiv) according

to the general procedure, AgPF₆(9.49 mg, 0.04 mmol, 2.0 equiv) was

used. Activated complex 13c-Ni-CyHex-PF₆(21.5 mg, 0.02 mmol,

89%) was isolated as a green solid.

C₄₆H₅₂B₂F₈N₆NiO₂Pd mol wt: 1059.67. Mp: >200 °C dec. [α]²⁰

=

D

−687.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CD₂Cl₂): δ

7.85 (d, J = 8.3, 2 H, CH_Imid), 7.62 (d, J = 2.5, 2 H, CH_Ar), 7.51−7.45

(m, 4 H, CH_Imid), 7.38−7.36 (m, 2 H, CH_Imid, 2 H, NCH), 7.28 (d, J

= 2.5, 2 H, NCH_Ar), 6.83 (d, J = 14.9, 2 H, C_ArCH₂), 5.57 (d, J = 14.9,

2 H, C_ArCH₂), 3.45 (s, 6 H, NCH₃), 3.04−3.03 (m, 2 H, N(CH)_Ring),

2.42−2.40 (m, 2 H, (CH₂)_Ring), 1.81−1.79 (m, 2 H, (CH₂)_Ring), 1.26−

1.22 (m, 4 H, (CH₂)_Ring), 1.20 (s, 18 H, C(CH₃)₃). ¹³C NMR (125

MHz, CD₂Cl₂): δ 162.0, 154.6, 154.5, 143.7, 136.6, 135.5, 133.4,

132.5, 125.9, 125.7, 124.4, 122.3, 112.2, 111.5, 70.1, 48.1, 34.9, 34.2,

1

C₅₄H₆₄F₁₂N₆NiO₂P₂Pd mol wt: 1284.17. Mp: >200 °C dec. [α]²⁰

D

= −456.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂): δ

7.45 (d, J = 2.5, 2 H, CH_Ar), 7.42 (d, J = 1.9, 2 H, NCH_Imid), 7.26−7.22

(m, 2 H, CH_Ar, 2 H, CH_Mes, 2 H, NCH), 7.09 (br, 2 H, CH_Mes), 6.94

(d, J = 1.9, 2 H, NCH_Imid), 4.72 (d, J = 14.8, 2 H, C_ArCH₂), 4.37 (d, J =

14.8, 2 H, C_ArCH₂), 2.92−2.90 (m, 2 H, N(CH)_Ring), 2.41 (s, 6 H, p-

CH₃C_Mes), 2.39−1.37 (m, 2 H, (CH₂)_Ring), 1.82−1.80 (m, 2 H,

(CH₂)_Ring), 1.77 (s, 6 H, o-CH₃C_Mes), 1.55 (s, 6 H, o-CH₃C_Mes), 1.25−

1.22 (m, 4 H, (CH₂)_Ring), 1.24 (s, 18 H, C(CH₃)₃). ¹³C NMR (125

MHz, CD₂Cl₂): δ 162.1, 154.0, 149.2, 144.2, 142.0, 137.7, 137.4,

134.3, 134.1, 133.7, 130.7, 135.5, 126.3, 124.2, 122.5, 121.6, 70.7, 50.4,

31.2 (3×), 29.8, 24.3. IR (solid): v 2956, 2868, 1632, 1568, 1461,

̃

1413, 1397, 1365, 1346, 1282, 1248, 1230, 1202, 1014, 871, 834, 809,

752, 696, 638, 575, 562. HRMS (ESI) m/z: calcd for [M − BF₄]⁺

C₄₆H₅₂BF₄N₆NiO₂Pd, 973.2568; found, 1973.2527.

34.3, 31.1 (3×), 29.4, 24.3, 21.2, 18.1, 18.0. IR (solid): v 2956, 2867,

̃

1627, 1566, 1463, 1414, 1365, 1308, 1277, 1250, 1228, 1190, 1165,

1106, 1044, 936, 837, 791, 737, 702, 689. HRMS (ESI) m/z: calcd for

[M − PF₆]⁺C₅₄H₆₄F₆N₆NiO₂PPd, 1139.3116; found, 1139.3094.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-mesityl-1H-

imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II) Diacetate

(12c-Ni-CyHex-OAc). For the anion exchange of complex 7c-Ni-

CyHex (20.00 mg, 0.02 mmol, 1.0 equiv) according to the general

procedure, AgOAc (6.27 mg, 0.04 mmol, 2.0 equiv) was used.

Activated complex 13c-Ni-CyHex-OAc (23.7 mg, 0.02 mmol, 98%, dr

= 1.1:1) was isolated as a green solid.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO,κO)-3,1-phenylene]methylene]bis[1-methyl-

1H-benzo[d]imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium-

(II) Ditriﬂate (13d-Ni-CyHex-OTf). For the anion exchange of complex

7d-Ni-CyHex (15.00 mg, 0.02 mmol, 1.0 equiv) according to the

general procedure, AgOTf (8.05 mg, 0.03 mmol, 2.0 equiv) was used.

Activated complex 13d-Ni-CyHex-OTf (16.60 mg, 0.01 mmol, 89%)

was isolated as a green solid.

C₄₈H₅₂F₆N₆NiO₈PdS₂mol wt: 1184.19. Mp: >200 °C dec. [α]²⁰

=

D

−534.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CD₂Cl₂): δ

8.50 (br, 2 H, CH_Ar), 7.89 (d, J = 8.5, 2 H, CH_Imid), 7.57 (br, 2 H,

CH_Ar), 7.51 (t, J = 7.5, 2 H, CH_Imid), 7.43−7.37 (m, 4 H, CH_Imid), 7.33

(d, J = 12.7, 2 H, C_ArCH₂), 5.53 (d, J = 12.7, 2 H, C_ArCH₂), 3.56 (s, 6

H, NCH₃), 2.95−2.94 (m, 2 H, N(CH)_Ring), 2.40−2.38 (m, 2 H,

(CH₂)_Ring), 1.50−1.47 (m, 2 H, (CH₂)_Ring), 1.22 (s, 18 H, C(CH₃)₃),

1.18−1.13 (m, 4 H, (CH₂)_Ring). ¹³C NMR (125 MHz, CD₂Cl₂): δ

220.7, 156.5, 156.2, 145.2, 136.2, 135.9, 132.9, 129.2, 125.7, 125.5,

1

C₅₈H₇₀N₆NiO₆Pd mol wt: 1112.33. Mp: 151−155 °C dec. [α]²⁰

=

D

1

−440.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CD₂Cl₂): δ

7.76 (br, J = 1.9, 2 H, NCH_Imid), 7.43 (br, 2 H, CH_Ar), 7.39 (s, 2 H,

NCH), 7.00 (br, 2 H, CH_Mes), 6.98 (d, J = 2.5, CH_Ar) 6.96 (d, J =

1.9, 2 H, NCH_Imid), 6.86 (br, 2 H, CH_Mes), 5.39 (d, J = 13.7, 2 H,

C_ArCH₂), 5.32 (d, J = 13.7, 2 H, C_ArCH₂), 3.04 (br, 2 H, N(CH)_Ring),

2.47−2.41 (m, 2 H, (CH₂)_Ring), 2.31 (s, 6 H, o-CH₃C_Mes), 2.24 (s, 6 H,

o-CH₃C_Mes), 1.96 (s, 6 H, O₂CCH₃) 1.88−1.86 (m, 2 H, (CH₂)_Ring),

1.73 (s, 6 H, p-CH₃C_Mes), 1.35−1.28 (m, 4 H, (CH₂)_Ring), 1.08 (s, 18

H, C(CH₃)₃). ¹³C NMR (125 MHz, CD₂Cl₂): δ 160.6, 157.9, 139.1,

138.2, 135.8, 135.0, 134.8, 133.4, 129.5, 129.3, 129.2, 128.9, 127.1,

124.5, 123.2, 122.6, 119.5, 70.2, 52.0, 33.8, 31.2 (3×), 29.7, 28.9, 24.4,

112.3, 111.5, 48.6, 39.8, 35.1, 34.1, 31.6 (3×), 25.1. IR (solid): v 2953,

̃

2865, 1631, 1567, 1461, 1396, 1365, 1345, 1223, 1155, 1025, 834, 809,

744, 696, 635, 573, 516. HRMS (ESI) m/z: calcd for [M − OTf]⁺

C₄₇H₅₂F₃N₆NiO₅PdS, 1035.2052; found, 1035.2050.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

benzo[d]imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II)

Ditosylate (12d-Ni-CyHex-OTs). For the anion exchange of complex

7d-Ni-CyHex (15.00 mg, 0.02 mmol, 1.0 equiv) according to the

general procedure, AgO₂CC₃F₇(8.75 mg, 0.03 mmol, 2.0 equiv) was

used. Activated complex 12d-Ni-CyHex-OTs (16.5 mg, 0.01 mmol,

86%, dr = 2.3:1) was isolated as an orange solid.

21.0, 17.9, 17.8. IR (solid): v 2949, 2861, 1618, 1600, 1546, 1447,

̃

1386, 1364, 1311, 1271, 1220, 1163, 1130, 1104, 1043, 1015, 934, 850,

836, 799, 736, 667, 615, 555, 526. HRMS (ESI) m/z: calcd for [M −

OAc]⁺C₅₆H₆₇N₆NiO₄Pd, 1053.3608; found, 1053.3595.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO,κO)-3,1-phenylene]methylene]bis[1-methyl-

1H-benzo[d]imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium-

(II) Bis(hexaﬂuorophosphate) (13d-Ni-CyHex-PF₆). For the anion

exchange of complex 7d-Ni-CyHex (11.60 mg, 0.01 mmol, 1.0 equiv)

according to the general procedure, AgPF₆(6.13 mg, 0.02 mmol, 2.0

equiv) was used. Activated complex 13d-Ni-CyHex-PF₆(7.80 mg,

0.01 mmol, 55%) was isolated as a green solid.

C₆₀H₆₆N₆NiO₈PdS₂mol wt: 1228.44. Mp: >200 °C dec. [α]²⁰

=

D

−85.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂, main

isomer): δ 8.33 (d, J = 6.4, 2 H, CH_Imid), 7.98 (br, 4 H, CH_OTs), 7.98

(br, 2 H, NCH), 7.56 (d, J = 2.5, 2 H, CH_Ar), 7.15−7.13 (m, 2 H,

CH_Imid), 7.05 (d, J = 2.5, 2 H, CH_Ar), 6.86 (t, J = 7.6, 2 H, CH_Imid),

6.53 (br, 4 H, CH_OTs), 6.26 (d, J = 8.5, 2 H, CH_Imid), 5.68 (d, J = 14.2,

128

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

2 H, C_ArCH₂), 5.23 (d, J = 13.7, 2 H, C_ArCH₂), 4.21 (s, 6 H, NCH₃),

2.50 (br, 2 H, N(CH)_Ring), 2.14−2.12 (m, 2 H, (CH₂)_Ring), 1.93 (br, 6

H, C_OTsCH₃), 1.69−1.67 (m, 2 H, (CH₂)_Ring), 1.27 (s, 18 H,

C(CH₃)₃), 1.05−0.99 (m, 4 H, (CH₂)_Ring). ¹³C NMR (125 MHz,

CD₂Cl₂, main isomer): δ 174.6, 162.1, 157.6, 141.3, 139.1, 128.8 (2×),

126.0 (2×), 125.1 (2×), 124.5, 123.4, 123.2, 123.1, 119.6, 113.3, 112.4

(2×), 110.5, 69.7, 56.3, 39.6, 37.2, 32.5, 31.6 (3×), 28.9, 24.6. IR

7.00 (d, J = 1.9, 2 H, NCH_Imid), 6.15 (d, J = 14.7, 2 H, C_ArCH₂), 4.60

(d, J = 14.7, 2 H, C_ArCH₂), 2.02 (s, 6 H, C_BiPhCH₃), 1.26 (s, 18 H,

C(CH₃)₃). ¹³C NMR (125 MHz, CD₂Cl₂): δ 163.0, 154.6, 145.8,

143.3, 143.1, 139.1, 137.5, 136.6, 133.5, 131.3, 130.1, 129.5 (2×),

129.1, 128.8, 124.0 (2×), 123.1, 122.6, 122.1, 121.6, 121.2, 50.4, 33.2,

29.8 (3×), 18.4. IR (solid): v 3143, 2960, 2360, 1674, 1605, 1560,

̃

1498, 1459, 1429, 1364, 1276, 1257, 1235, 1219, 1188, 1107, 1044,

1024, 953, 835, 791, 767, 736, 707, 694, 675, 556, 533, 509. HRMS

(ESI) m/z: calcd for [M − 2PF₆]²⁺C₅₆H₅₄N₆O₂Pd₂, 528.1197; found,

528.1200.

(solid): v 2952, 2863, 1650, 1621, 1552, 1460, 1395, 1362, 1346, 1274,

̃

1247, 1222, 1177, 1121, 1034, 1011, 812, 744, 681, 568. HRMS (ESI)

m/z: calcd for [M − OTs]⁺C₅₃H₅₉N₆NiO₅PdS, 1057.2650; found,

1057.2626.

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

benzo[d]imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II)

Bis(heptaﬂuorobutyrate) (12d-Ni-CyHex-O₂CC₃F₇). For the anion

exchange of complex 7d-Ni-CyHex (15.00 mg, 0.02 mmol, 1.0 equiv)

according to the general procedure, AgO₂CC₃F₇(10.06 mg, 0.03

mmol, 2.0 equiv) was used. Activated complex 12d-Ni-CyHex-

O₂CC₃F₇(14.6 mg, 0.01 mmol, 71%, dr = 1.9:1) was isolated as a red

solid.

ASSOCIATED CONTENT

* Supporting Information

Text, ﬁgures, and CIF ﬁles giving experimental procedures,

characterization data for all new products, and crystallographic

data. This material is available free of charge via the Internet at

http://pubs.acs.org.

■

S

AUTHOR INFORMATION

Corresponding Author

*E-mail: rene.peters@oc.uni-stuttgart.de.

Notes

C₅₄H₅₂F₁₄N₆NiO₆Pd mol wt: 1312.12. Mp: >200 °C dec. [α]²⁰

=

■

D

−208.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂, main

isomer): δ 7.67 (d, J = 2.5, 2 H, CH_Ar), 7.31 (d, J = 8.0, 2 H, CH_Imid),

7.21−7.13 (s, 2 H, CH_Imid, 2 H, NCH), 7.09 (d, J = 2.5, 2 H, CH_Ar),

6.90 (t, J = 7.9, 2 H, CH_Imid), 6.42 (d, J = 8.0, 2 H, CH_Imid), 6.06 (d, J =

13.7, 2 H, C_ArCH₂), 5.43 (d, J = 13.7, 2 H, C_ArCH₂), 4.38 (s, 6 H,

NCH₃), 2.59−2.58 (m, 2 H, N(CH)_Ring), 2.19−2.18 (m, 2 H,

(CH₂)_Ring), 1.73−1.71 (m, 2 H, (CH₂)_Ring), 1.28 (s, 18 H, C(CH₃)₃),

1.09−1.06 (m, 4 H, (CH₂)_Ring). ¹³C NMR (125 MHz, CD₂Cl₂, main

isomer): δ 168.1, 162.3, 157.8, 137.5, 135.5, 134.8, 134.6, 130.0, 123.8,

123.1 (3×), 119.7, 112.7, 110.3, 69.7, 54.6, 35.3, 34.1, 31.6 (3×), 28.9,

The authors declare no competing ﬁnancial interest.

ACKNOWLEDGMENTS

This work was ﬁnancially supported by the Deutsche

Forschungsgemeinschaft (DFG, PE 818/3-1). We thank

Dipl.-Chem. Martina Bubrin (Kaim group, Universitat

■

̈

24.6. IR (solid): v 2953, 2869, 1686, 1620, 1550, 1456, 1396, 1367,

̃

Stuttgart) for recording the UV−vis spectra.

1329, 1271, 1203, 1157, 1114, 1077, 1056, 1025, 962, 926, 839, 812,

739, 718, 634, 580, 551. HRMS (ESI) m/z: calcd for [M − O₂CC₃F₇]⁺

C₅₀H₅₂F₇N₆NiO₄Pd, 1099.2321; found, 1099.2282.

REFERENCES

(1) Ma, J.-A.; Cahard, D. Angew. Chem., Int. Ed. 2004, 43, 4566.

(2) Wilcox, D. E. Chem. Rev. 1996, 96, 2435.

■

{[1,1′-[(1R,2R)-1,2-Cyclohexanediylbis[imino-κN[5-(1,1-dimethy-

lethyl)-2-(hydroxy-κO)-3,1-phenylene]methylene]bis[1-methyl-1H-

benzo[d]imidazol-1-yl-2(3H)-ylidene]](2−)]nickel(II)}palladium(II)

Diacetate (12d-Ni-CyHex-OAc). For the anion exchange of complex

7d-Ni-CyHex (15.00 mg, 0.02 mmol, 1.0 equiv) according to the

general procedure, AgOAc (5.23 mg, 0.03 mmol, 2.0 equiv) was used.

Activated complex 12d-Ni-CyHex-OAc (15.30 mg, 0.02 mmol, 97%,

dr = 3.1:1) was isolated as a orange solid.

(3) Selected reviews about bimetallic catalysis: (a) van den Beuken,

E. K.; Feringa, B. L. Tetrahedron 1998, 54, 12985. (b) Shibasaki, M.;

Matsunaga, S. Chem. Soc. Rev. 2006, 35, 269. (c) Shibasaki, M.; Kanai,

M.; Matsunaga, S.; Kumagai, N. Acc. Chem. Res. 2009, 42, 1117.

(4) (a) Yoon, T. P.; Jacobsen, E. N. Science 2003, 299, 1691.

(b) Katsuki, T. Synlett 2003, 281. (c) Matsumoto, K.; Saito, B.;

Katsuki, T. Chem. Commun. 2007, 35, 3619. (d) Mazet, C.; Jacobsen,

E. N. Angew. Chem., Int. Ed. 2008, 47, 1762. (e) Sammis, G. M.;

Jacobsen, E. N. J. Am. Chem. Soc. 2003, 125, 4442. (f) Sigman, M. S.;

Jacobsen, E. N. J. Am. Chem. Soc. 1998, 120, 5315. (g) Myers, J. K.;

Jacobsen, E. N. J. Am. Chem. Soc. 1999, 121, 8959.

(5) Reviews: (a) Herrmann, W. A. Angew. Chem., Int. Ed. 2002, 41,

1290. (b) Peris, E.; Crabtree, R. H. Coord. Chem. Rev. 2004, 248, 2239.

(c) Crudden, C. M.; Allen, D. P. Coord. Chem. Rev. 2004, 248, 2247.

(d) N-Heterocyclic Carbenes in Synthesis; Nolan, S. P., Ed.; Wiley-VCH:

Weinheim, Germany, 2006. (e) N-Heterocyclic Carbenes in Transition

Metal Catalysis; Glorius, F., Ed.; Springer: Berlin, 2007. (f) Diez-

Gonzalez, S.; Nolan, S. P. Coord. Chem. Rev. 2007, 251, 874.

(g) Kantchev, E. A. B.; O’Brien, C. J.; Organ, M. G. Angew. Chem., Int.

Ed. 2007, 46, 2768. (h) Hahn, F. E.; Jahnke, M. C. Angew. Chem., Int.

C₅₀H₅₈N₆NiO₆Pd mol wt: 1004.14. Mp: >200 °C dec. [α]²⁰

=

D

−379.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). ¹H NMR (500 MHz, CD₂Cl₂, main

isomer): δ 7.65 (d, J = 2.5, 2 H, CH_Ar), 7.28 (d, J = 8.5, 2 H, CH_Imid),

7.20 (s, 2 H, NCH), 7.13 (t, J = 7.7, 2 H, CH_Imid), 7.07 (d, J = 2.5, 2

H, CH_Ar), 6.85 (t, J = 7.7, 2 H, CH_Imid), 6.34 (d, J = 8.5, 2 H, CH_Imid),

5.98 (d, J = 14.0, 2 H, C_ArCH₂), 5.40 (d, J = 14.0, 2 H, C_ArCH₂), 4.07

(s, 6 H, NCH₃), 2.60 (br, 2 H, N(CH)_Ring), 2.20−2.18 (m, 2 H,

(CH₂)_Ring), 1.73−1.70 (m, 2 H, (CH₂)_Ring), 1.70 (s, O₂CCH₃), 1.26 (s,

18 H, C(CH₃)₃), 1.08−1.06 (m, 4 H, (CH₂)_Ring). ¹³C NMR (125

MHz, CD₂Cl₂, main isomer): δ 176.8, 174.4, 162.6, 157.7, 137.5,

135.6, 135.0, 134.8, 129.8, 124.7, 122.6, 122.5, 119.6, 112.6, 110.2,

69.9, 54.5, 35.4, 34.2, 31.7 (3×), 29.1, 24.8, 23.7. IR (solid): v 2952,

̃

2864, 1620, 1549, 1459, 1394, 1366, 1334, 1274, 1244, 1225, 1130,

1096, 1055, 1018, 840, 812, 742, 675, 577, 551. HRMS (ESI) m/z:

calcd for [M − OAc]⁺C₄₈H₅₅N₆NiO₄Pd, 945.2666; found, 945.2657.

{[1,1′-[(R)-2,2′-Bis[imino-κN[5-(1,1-dimethylethyl)-2-(hydroxy-

κO,κO)-3,1-phenylene]methylene]bis[1-phenyl-1H-imidazol-1-yl-

2(3H)-ylidene]-6,6′-dimethyl-1,1′-biphenyl](2−)]palladium(II)}-

palladium(II) Bis(hexaﬂuorophosphate) (13b-Pd-BiPh-PF₆). For the

anion exchange of complex 7b-Pd-BiPh (21.20 mg, 0.02 mmol, 1.0

equiv) according to the general procedure, AgPF₆(9.50 mg, 0.04

mmol, 2.0 equiv) was used. Activated complex 13b-Pd-BiPh-PF₆

(25.99 mg, 0.02 mmol, 100%) was isolated as a red solid.

Ed. 2008, 47, 3122. (i) Wurtz, S.; Glorius, F. Acc. Chem. Res. 2008, 41,

̈

1523. (j) Diez-Gonzalez, S.; Marion, N.; Nolan, S. P. Chem. Rev. 2009,

109, 3612. (k) Wolf, R.; Uhl, W. Angew. Chem., Int. Ed. 2009, 48, 6774.

(l) Droge, T.; Glorius, F. Angew. Chem., Int. Ed. 2010, 49, 6940.

̈

(6) For the use of bimetallic salen complexes with N₂O₂and O₄

coordination spheres in catalysis, see e.g.: (a) Shibasaki, M.;

Matsunaga, S.; Kumagai, N. Synlett 2008, 1583. (b) Handa, S.;

Gnanadesikan, V.; Matsunaga, S.; Shibasaki, M. J. Am. Chem. Soc. 2007,

129, 4900. (c) Handa, S.; Nagawa, K.; Sohtome, Y.; Matsunaga, S.;

Shibasaki, M. Angew. Chem., Int. Ed. 2008, 47, 3230. (d) Sohtome, Y.;

Kato, Y.; Handa, S.; Aoyama, N.; Nagawa, K.; Matsunaga, S.; Shibasaki,

M. Org. Lett. 2008, 10, 2231. (e) Chen, Z.; Morimoto, H.; Matsunaga,

S.; Shibasaki, M. J. Am. Chem. Soc. 2008, 130, 2170. (f) Chen, Z.;

C₅₆H₅₄F₁₂N₆O₂P₂Pd₂mol wt: 1345.84. Mp: >200 °C dec. [α]²⁰

=

D

+204.0° (c = 0.1 g dL⁻¹, CH₂Cl₂). H NMR (500 MHz, CD₂Cl₂): δ

7.67−7.65 (m, 6 H, CH_Ph), 7.63 (d, J = 2.5, 2 H, CH_Ar), 7.51−7.45 (m,

4 H, CH_BiPh, 4 H, CH_Ph), 7.40 (s, 2 H, CNH), 7.35 (d, J = 2.5, 2 H,

CH_Ar), 7.23 (d, J = 7.4, 2 H, CH_BiPh), 7.05 (d, J = 1.9, 2 H, NCH_Imid),

1

129

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Organometallics

Article

Yakura, K.; Matsunaga, S.; Shibasaki, M. Org. Lett. 2008, 10, 3239.

(g) Chen, Z.; Furutachi, M.; Kato, Y.; Matsunaga, S.; Shibasaki, M.

Angew. Chem., Int. Ed. 2009, 48, 2218. (h) Mouri, S.; Chen, Z.;

Matsunaga, S.; Shibasaki, M. Chem. Commun. 2009, 5138. (i) Mouri,

S.; Chen, Z.; Mitsunuma, H.; Furutachi, M.; Matsunaga, S.; Shibasaki,

M. J. Am. Chem. Soc. 2010, 132, 1255.

(7) For bimetallic catalysts carrying two salen units, see e.g. ref 4d

and: Konsler, R. G.; Karl, J.; Jacobsen, E. N. J. Am. Chem. Soc. 1998,

120, 10780.

(8) Formation of salen ligands equipped with an ammonium moiety

for the formation of cooperative organic ion pair/Lewis acid catalysts:

(a) Kull, T.; Peters, R. Angew. Chem., Int. Ed. 2008, 47, 5461. (b) Kull,

T.; Cabrera, J.; Peters, R. Chem. Eur. J. 2010, 16, 9132. (c) Meier, P.;

Broghammer, F.; Latendorf, K.; Rauhut, G.; Peters, R. Molecules 2012,

17, 7121.

W.; Peters, R. Organometallics 2012, 31, 6365. (h) Weber, M.; Jautze,

S.; Frey, W.; Peters, R. Chem. Eur. J. 2012, 18, 14792.

(24) Reviews about the asymmetric synthesis of oxindoles: (a) Trost,

B. M.; Brennan, M. K. Synthesis 2009, 3003. (b) Zhou, F.; Liu, Y.-L.;

Zhou, J. Adv. Synth. Catal. 2010, 352, 1381.

(25) Selected examples for the 1,4-addition of oxindoles to

nitrooleﬁns: (a) Li, X.; Zhang, B.; Xi, Z.-G.; Luo, S. Z.; Cheng, J.-P.

Adv. Synth. Catal. 2010, 352, 416. (b) He, R.; Shirakawa, S.; Maruoka,

K. J. Am. Chem. Soc. 2009, 131, 16620. (c) Bui, T.; Syed, S.; Barbas, C.

F., III J. Am. Chem. Soc. 2009, 131, 8758.

(26) Selected reviews on conjugate additions: (a) Berner, O. M.;

Tedeschi, L.; Enders, D. Eur. J. Org. Chem. 2002, 1877.

(b) Christoffers, J.; Baro, A. Angew. Chem., Int. Ed. 2003, 42, 1688.

(c) Christoffers, J.; Koripelly, G.; Rosiak, A.; Rossle, M. Synthesis 2007,

̈

1279. (d) Tsogoeva, S. B. Eur. J. Org. Chem. 2007, 1701.

(27) Kato, Y.; Furutachi, M.; Chen, Z.; Mitsunuma, H.; Matsunaga,

S.; Shibasaki, M. J. Am. Chem. Soc. 2009, 131, 9168.

(28) For other Ni catalysts for this reaction, see: Han, Y.-Y.; Wu, Z.-

J.; Chen, W.-B.; Du, X.-L.; Zhang, X.-M.; Yuan, W.-C. Org. Lett. 2011,

13, 5064.

(9) Wang, H. M. J.; Lin, I. J. B. Organometallics 1998, 17, 972.

(10) Liu, Z.; Zhang, T.; Shi, M. Organometallics 2008, 27, 2668.

(11) Fremont, P.; Scott, N. M.; Stevens, E. D.; Ramnial, T.;

́

Lightbody, O. C.; Macdonald, C. L. B.; Clyburne, J. A. C.; Abernethy,

C. D.; Nolan, S. P. Organometallics 2005, 24, 6301.

(12) Review: Garrison, J. C.; Youngs, W. J. Chem. Rev. 2005, 105,

3978.

(13) The bis-silver complex 8-M¹might also contain a Ag−Ag

interaction or bridging halide anions. For an excellent compilation of

possible structures, see ref 12.

(14) However, exceptions are also known where silver NHC

complexes showing a distinct ¹⁰⁷Ag/¹⁰⁹Ag−¹³C coupling pattern

undergo a rapid transmetalation, in particular with macrocyclic or

supramolecular polycarbene structures. See e.g.: (a) Hahn, F. E.;

Radloff, C.; Pape, T.; Hepp, A. Chem. Eur. J. 2008, 14, 10900. (b) Rit,

A.; Pape, T.; Hahn, F. E. J. Am. Chem. Soc. 2010, 132, 4572. (c) Rit, A.;

Pape, T.; Hepp, A.; Hahn, F. E. Organometallics 2011, 30, 334.

(15) For an example with Pd₂(dba)₃, see: Sommer, W. J.; Weck, M.

Adv. Synth. Catal. 2006, 348, 2101.

(16) O’Connor, M. J.; Ernst, R. E.; Holm, R. H. J. Am. Chem. Soc.

1968, 90, 4561.

(17) Supplementary crystallographic data for 7a-CyHex-Ni have

been deposited with the Cambridge Crystallographic Data Centre as

deposition 892350. This material is available free of charge via the

Internet at http://pubs.acs.org and http://www.ccdc.cam.ac.uk/

products/csd/request/.

(18) Tulloch, A. A. D.; Danopoulos, A. A.; Winston, S.; Kleinhenz, S.;

Eastham, G. Dalton Trans. 2000, 4499.

(19) Lee, K. M.; Wang, H. M. J.; Lin, I. C. B. Dalton Trans. 2002,

2852.

(20) 11 is also available in a single step from ligand 4a-CyHex

(possessing two bromide counterions for chloride) by treatment with

PdCl₂(MeCN)₂(2.0 equiv) and K₂CO₃(4.0 equiv) in DMF at 100 °C

in 39% yield.

(21) Supplementary crystallographic data for 13a-CyHex-Ni-PF₆and

13d-CyHex-Ni-PF₆have been deposited with the Cambridge

Crystallographic Data Centre as depositions 892349 and 899982,

respectively. This material is available free of charge via the Internet at

http://pubs.acs.org and http://www.ccdc.cam.ac.uk/products/csd/

request/.

(22) Selected applications: (a) Koch, F. M.; Peters, R. Chem. Eur. J.

2011, 17, 3679. (b) Tiseni, P. S.; Peters, R. Chem. Eur. J. 2010, 16,

2503. (c) Zajac, M.; Peters, R. Chem. Eur. J. 2009, 15, 8204. (d) Tiseni,

P. S.; Peters, R. Org. Lett. 2008, 10, 2019. (e) Koch, F. M.; Peters, R.

Angew. Chem., Int. Ed. 2007, 46, 2685. (f) Tiseni, P. S.; Peters, R.

Angew. Chem., Int. Ed. 2007, 46, 5325.

(23) Bimetallic catalysts: (a) Jautze, S.; Seiler, P.; Peters, R. Angew.

Chem., Int. Ed. 2007, 46, 1260. (b) Jautze, S.; Seiler, P.; Peters, R.

Chem. Eur. J. 2008, 14, 1430. (c) Jautze, S.; Diethelm, S.; Frey, W.;

Peters, R. Organometallics 2009, 28, 2001. (d) Jautze, S.; Peters, R.

Angew. Chem., Int. Ed. 2008, 47, 9284. (e) Weber, M.; Jautze, S.; Frey,

W.; Peters, R. J. Am. Chem. Soc. 2010, 132, 12222. (f) Weber, M.; Frey,

W.; Peters, R. Adv. Synth. Catal. 2012, 354, 1443. (g) Weiss, M.; Frey,

130

dx.doi.org/10.1021/om3008629 | Organometallics 2013, 32, 112−130

Article Doi

Homo-and heterobimetallic Pd-, Ag-, and Ni-hybrid salen-bis-NHC complexes

DOI: 10.1021/om3008629

Source and publish data:

Authors:

Article abstract of DOI:10.1021/om3008629

Full text of DOI:10.1021/om3008629

Products guided by the article

R&D Labs maybe for 1416171-27-1

Relevant to this article

Hot Product