Diaminocarbene- and Fischer-carbene complexes of palladium and nickel by oxidative insertion: Preparation, structure, and catalytic activity

FULL PAPER

Diaminocarbene- and Fischer-Carbene Complexes of Palladium and Nickel

by Oxidative Insertion: Preparation, Structure, and Catalytic Activity

Doris Kremzow, Gꢀnter Seidel, Christian W. Lehmann, and Alois Fꢀrstner*^[a]

Abstract: Oxidative insertion of

[Pd(PPh₃)₄] or [Ni(cod)₂]/PPh₃into the

clic carbene) and metal complexes with

acyclic diaminocarbene ligands illus-

trates this aspect. Furthermore it is

shown that oxidative insertion also

paves a way to prototype Fischer car-

benes of Pd^II. Since the required start-

ing materials are readily available from

urea- or thiourea derivatives, this novel

approach allows for substantial struc-

tural variations of the ligand backbone.

The catalytic performance of the re-

sulting library of nickel- and palladi-

um–carbene complexes has been evalu-

ated by applications to prototype

Suzuki-, Heck-, and Kumada–Corriu

cross-coupling reactions as well as

Buchwald–Hartwig aminations. It was

found that even Fischer carbenes show

appreciable catalytic activity. More-

over, representative examples of all

types of neutral and cationic metal–car-

bene complexes formed in this study

have been characterized by X-ray crys-

tallography.

ꢀ

C Cl bond of various 2-chloroimidazo-

linium- and other -amidinium salts af-

fords metal–diaminocarbene complexes

in good to excellent yields. This proce-

dure is complementary to existing

methodology in which the central

metal does not change its oxidation

state, and therefore allows to incorpo-

rate carbene fragments that are diffi-

cult to access otherwise. The prepara-

tion of a variety of achiral as well as

enantiomerically pure, chiral metal–

NHC complexes (NHC = N-heterocy-

Keywords:

carbenes

·

cross-coupling

· homogeneous

catalysis · nickel · palladium

Introduction

plex to the specific requirements of a given metal-catalyzed

transformation. Although many recent reports bear witness

for the favorable profile of metal–NHC complexes in syn-

thesis,^[6]applications to olefin metathesis,^[8]palladium- and

nickel-catalyzed cross-coupling reactions,^[9]and hydrosilyla-

tion^[10]deserve particular mentioning.

Metal complexes of N-heterocyclic carbenes (NHCs) were

pioneered in the 1960 s by Wanzlick^[1]and ꢀfele.^[2]Although

their organometallic chemistry has been intensively studied

early on,^[3]it was not until the last decade that the favorable

properties of such complexes were fully appreciated by the

scientific community. This development was triggered by Ar-

duengoꢁs seminal discovery that various NHCs can be isolat-

ed in pure form,^[4,5]and by the recognition of their potential

as ancillary ligands for many metal catalyzed transforma-

tions.^[6,7]Not only represent NHCs mere substitutes for

phosphine ligands, but it became increasingly evident that

they impart superior properties to various metal templates

in terms of stability and activity. Moreover, the ease of syn-

thesis allows for structural variations which may be used to

adjust the electronic as well as steric properties of the com-

The most general procedure for the preparation of metal–

NHC complexes known to date relies on simple ligand ex-

change and therefore hinges upon the ability to form the

corresponding carbenes as a discrete or a transient species

by the methods depicted in Scheme 1.^[11–14]This is one of the

reasons why the highly stabilized five-membered NHCs

A–C are most commonly used because they are particularly

well amenable to this synthesis route. They constitute, how-

ever, only one particular class of “stable” (or metastable)

carbene species;^[15–17]other types are depicted in Scheme 2.

Despite some highly promising chemical and physical prop-

erties,^[18]such species have only rarely been used as ancillary

ligands in catalysis, not least because they are somewhat

more delicate to handle and therefore less suited for proc-

essing via ligand exchange.^[19,20]To explore the full potential

of (acyclic) diaminocarbene–metal catalysts with ligands

such as D–H, it seems necessary to develop practical alter-

native methods for their preparation.

[a] Dr. D. Kremzow, Ing. G. Seidel, Dr. C. W. Lehmann,

Prof. A. Fꢂrstner

Max-Planck-Institut fꢂr Kohlenforschung

45470 Mꢂlheim/Ruhr (Germany)

Fax : (+49)208-306-2994

E-mail: fuerstner@mpi-muelheim.mpg.de

Chem. Eur. J. 2005, 11, 1833 – 1853

DOI: 10.1002/chem.200400928

ꢃ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

1833

though, it seems that this potentially general method has

not been applied to the synthesis of metal–imidazol(idin)-2-

ylidene complexes except for one special case.^[29]This ap-

proach, however, promises a broad substrate scope and

might allow for substantial structural variations since the re-

quired precursor salts are easily obtained from cyclic ureas

or thioureas on treatment with for example oxalyl chlo-

ride.^[30]Moreover, the N,N’-dimethyl imidazolinium deriva-

tives 1a–c (X = PF₆, BF₄, Cl) are even commercially availa-

ble and have been widely used as excellent dehydrating

agents for a host of esterification-, chlorination-, oxidation-,

and rearrangement reactions as well as for heterocycle syn-

thesis.^[31,32]

Treatment of the imidazolinium salt 1a (X=PF₆) with an

equimolar amount of [Pd(PPh₃)₄] in refluxing CH₂Cl₂leads

to a clean reaction which can be nicely monitored by

³¹P NMR spectroscopy. Initially, two sets of signals at d_P=

31.8 (d, J=24 Hz) and d_P=21.2 (d, J=24 Hz) are detected

which converge over a period of about 6 h to a singlet at

d_P=22.5 ppm; two equivalents or PPh₃are released concom-

itantly. This course reflects the formation of cis-2a as the

primary product which isomerizes with time to the more

stable trans-2a. After extraction of the free PPh₃, trans-2a

was isolated as a white solid in analytically pure form

(72%) by recrystallization from CHCl₃. The structure of this

ionic palladium–NHC complex in the solid state is depicted

in Figure 1. The imidazolinium salt 1b (X=BF₄) reacts anal-

ogously affording compound trans-2b (d_P=22.8 ppm) in

similar yield (Scheme 3).^[33]

Scheme 1. Common routes to metal–imidazol(idin)-2-ylidene complexes:

a) base (e. g. KOtBu, KH, BuLi) in THF or liquid NH₃; b) thermolysis

(a-elimination); c) cf. ref. [3]; [d] K in THF.

Scheme 2. Prototype diaminocarbene and related carbene fragments.

As part of our ongoing studies in this field,^[21–23]we con-

sidered that oxidative insertion of a low-valent metal into an

appropriate 2-halo-amidinium salt may open an as yet large-

ly unexplored but potentially very useful entry. Outlined

below is the reduction of this concept to practice which pro-

vides access to a wide variety of metal-diaminocarbene- and

even prototype Fischer-carbene complexes of palladium and

nickel that are difficult to make otherwise.^[24]Their structur-

al properties and potential as catalysts for cross-coupling re-

actions are also outlined.

Results and Discussion

Palladium–NHC complexes: As shown in Scheme 1, the

most common synthesis route for metal–diaminocarbene

complexes in general and metal–NHC complexes in particu-

lar involves a ligand exchange or salt metathesis in which

the metal template does not change its oxidation state.

Therefore it seemed likely at the outset of this project that

any route based on oxidative insertion might potentially be

complementary in scope.^[25]

The formation of Fischer-carbene complexes by oxidative

addition has precedence in early investigations by Lap-

pert,^[26]Stone^[27]and others^[28]who showed that certain metal

templates are able to react with for example iminium-, 2-

chlorothiazolium- or 2-chloro-1-methylpyridinum salts to

afford the corresponding carbene complexes. Surprisingly

ꢀ

Figure 1. Molecular structure of complex 2a. The PF₆counterion is

omitted for clarity.

The reactivity of chloride 1c (X=Cl) follows the same

trend giving rise to the expected cationic complex trans-2c

(d_P=22.8 ppm) which was again fully characterized by X-

ray crystallography.^[24]The solution structure must be similar

because the carbene center in trans-2c resonates as a triplet

at d_C=194.9 ppm (J=6.9 Hz), thus indicating the presence

of two phosphorous atoms at degenerate positions. Howev-

er, the crude mixture formed from 1c and [Pd(PPh₃)₄] invar-

iably contains small amounts of other complexes in addition

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Carbene Complexes

FULL PAPER

Scheme 3. a) [Pd(PPh₃)₄], CH₂Cl₂, reflux, 72% (trans-2a), 74% (trans-

2b), 87% (trans-2c).

to 2c; one of them (d_P=27.7 ppm) cleanly regenerates when

recrystallized 2c is dissolved in CD₂Cl₂or THF. Although

we were unable so far to isolate this new compound on a

preparative scale, crystals were picked out from a co-precip-

itate and were analyzed by X-ray crystallography,^[34]which

showed that this product is the neutral, cis-configured palla-

dium dichloride complex 3 (Scheme 4).^[35,36]Therefore the

particular behavior of 2c in solution is deemed to reflect the

higher affinity of the chloride ion to Pd^IIcompared with the

Scheme 5. a) Thiophosgene, Et₃N, CH₂Cl₂, 82%; b) oxalyl chloride, tolu-

ene, 608C; c) AgPF₆, CH₂Cl₂, 71% (6b), 79% (7b), 70% (8b).

ꢀ

only weakly coordinating anions PF₆or BF₄escorting

compounds 2a,b, respectively.

Scheme 4. Equilibrium between the cationic and the neutral form of the

palladium–NHC complex.

Next, we probed the applicability of this novel method to

the formation of chiral Pd^II–NHC complexes.^[37]To this end,

the enantiomerically pure 1,2-diamine 4 was converted into

the corresponding thiourea derivative 5 (Figure 2). Exposure

of 5 to oxalyl chloride in toluene at 608C cleanly afforded

the desired imidazolinium chloride 6a (X=Cl) (Scheme 5).

Compounds 7 and 8 were prepared analogously. All of them

reacted smoothly with [Pd(PPh₃)₄] in CH₂Cl₂at ambient

temperature to afford the corresponding enantiopure palla-

dium–NHC complexes. Interestingly though, substrates 7

and 8 (Scheme 6) favor the neutral, cis-configured palladium

dichloride complexes 11 (Figure 5) and 13 (Figure 7), re-

spectively,^[35]whereas the closely related proline derived salt

6a (X=Cl) furnished the cationic trans-configured complex

9 (X=Cl) as the major product. Its structure was also unam-

biguously confirmed by X-ray analysis (Figure 3). In analogy

to the results described above for the achiral complex 2c,

Scheme 6. a) [Pd(PPh₃)₄], CH₂Cl₂, RT, 67% (9a, X=Cl), 85% (11), 70%

(13); b) [Pd(PPh₃)₄], toluene, 1008C, 71% (9b), 63% (10), 43% (12).

dissolution of 9 in CH₂Cl₂re-establishes an equilibrium be-

tween the cationic form and the corresponding neutral ver-

sion as judged by ³¹P NMR spectroscopy. The subtle prefer-

ences of the different precursors to form either neutral or

cationic complexes are not yet clear.

ꢀ

Exchange of the chloride counter-ion in 6–8a for PF₆

was easily achieved on treatment with AgPF₆in CH₂Cl₂.

The resulting chiral imidazolinium hexafluorophosphates

6b, 7b and 8b are equally amenable to oxidative insertion

of Pd⁰, although more forcing conditions had to be used.

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A. Fꢂrstner et al.

Figure 2. Molecular structure of thiourea 5.

Figure 5. Molecular structure of complex 11.

Figure 3. Molecular structure of complex 9a. The chloride counterion is

omitted for clarity.

ꢀ

Figure 6. Molecular structure of complex 12. The escorting PF₆counter-

ion is omitted for clarity.

ꢀ

Figure 4. Molecular structure of complex 9b. The PF₆counterion is

omitted for clarity.

Best results were obtained in toluene at 1008C. In two cases

were the resulting cationic NHC-complexes characterized

by X-ray crystallography. In line with their achiral counter-

parts 2a,b, both of them are trans-configured, likely due to

the strong trans-influence exerted by the carbene fragment

(Figures 4 and 6).

Other palladium–diaminocarbene complexes: Since many

amidinium salts other than the imidazolinium compounds

mentioned above are readily accessible on large scale, a gen-

eralization of this concept seemed possible. Therefore we

explored if oxidative addition can provide palladium com-

plexes bearing less common diaminocarbene ligands.

Figure 7. Molecular structure of complex 13.

The first aspect to be investigated was the effect of the

ring size. For this purpose, commercial DMPU 14 was con-

verted into 15a (X=Cl) on treatment with oxalyl chloride;

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Carbene Complexes

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subsequent reaction with [Pd(PPh₃)₄] under standard condi-

tions gave the desired Pd^II–1,3-dimethyl-3,4,5,6-tetrahydro-

pyrimidin-2-ylidene complex 16a (X=Cl) in good yield

ꢀ

(Scheme 7). The corresponding PF₆salt 15b behaved simi-

ꢀ

Figure 9. Molecular structure of complex 16b. The PF₆counterion is

omitted for clarity.

Scheme 7. a) Oxalyl chloride, CCl₄, 608C, 59%; b) AgPF₄, CH₂Cl₂, 90%;

c) [Pd(PPh₃)₄], 62% (16a), 61% (16b).

Even more gratifyingly, the commercial amidinium salt 18

derived from N,N’-carbonyldipiperidine 17 was exposed to

[Pd(PPh₃)₄] in toluene at 1008C, thus furnishing the diami-

nocarbene complex 19 in 50% yield after recrystallization

of the crude product (Scheme 8 and Figure 10). This result

must be seen in the light of previous experiences with the

corresponding free carbene F-1 (Scheme 9); although this

larly well, thus lending credence to the notion that the ring

size of the backbone has no significant effect on the out-

come of the reaction.^[38]The structure of these complexes in

the solid state is depicted in Figures 8 and 9.

Scheme 8. a) Oxalyl chloride, toluene, 608C; b) [Pd(PPh₃)₄], toluene,

1008C, 50%.

Figure 8. Top: Molecular structure of complex 16a. The chloride counter-

ion is omitted for clarity. Carbon atom C4 is disordered due to the crys-

tallographic mirror symmetry. Bottom: Space filling representation of

16a. The 1,3-dimethyl-3,4,5,6-tetrahydropyrimidin-2-ylidene ligand is

sandwiched between two phenyl rings. The chlorine (green) in trans posi-

tion to the carbene is readily accessible.

ꢀ

Figure 10. Molecular structure of complex 19. The PF₆counterion is

omitted for clarity.

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Scheme 9. Diaminocarbenes with acyclic backbone.

species was previously described by Alder et al.,^[39]it is

known to be rather unstable and has not yet found any ap-

plication as ancillary ligand for catalytically relevant metal

complexes. The same pertains to bis(dimethylamino)carbene

F-2. Although accessible in situ, this particular carbene

could not be isolated in pure form^[40]and was incorporated

into a metal complex only once.^[28a]Scheme 10 shows that

Figure 11. Molecular structure of complex 22.

ꢀ

Figure 12. Molecular structure of complex 23. The PF₆counterion is

omitted for clarity.

Scheme 10. a) Oxalyl chloride, toluene, 608C, 90%; b) [Pd(PPh₃)₄],

CH₂Cl₂, RT, 40%; c) [Pd(PPh₃)₄], toluene, 1008C, 48%.

oxidative insertion makes it easy to generate the corre-

sponding neutral or cationic Pd^II-complexes 22 and 23 of

this interesting ligand from the readily available amidinium

salts 21. The proposed structures were again confirmed by

X-ray crystallography (Figures 11 and 12).

Fischer-carbene complexes of palladium: Encouraged by the

results summarized above, a further extension of the scope

of this novel method was envisaged. Specifically, formal re-

placement of one of the N-atoms in a diaminocarbene by

heteroatoms X other than nitrogen or by an aromatic ring

renders the resulting carbenes of types G or H semistable at

best (Scheme 2); the corresponding metal complexes are

prototype Fischer carbenes.

Access to this series was gained on treatment of suitable

precursor salts with [Pd(PPh₃)₄] in CH₂Cl₂at ambient tem-

perature (for the chloride salts) or in toluene at 1008C (for

the hexafluorophosphates) as shown in Schemes 11–13. Al-

though the yields were somewhat lower than before—in par-

ticular for the cationic species 28, 33 and 35—this method is

Scheme 11. a) Oxalyl chloride, toluene, 608C, 91% (25a), 85% (25b);

b) AgPF₄, CH₂Cl₂, 76% (26a), 86% (26b); c) [Pd(PPh₃)₄], CH₂Cl₂, RT,

35% (27a), 64% (27b); d) [Pd(PPh₃)₄], toluene, 1008C, 30 % (28a),

24% (28b).

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Carbene Complexes

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Figure 14. Molecular structure of complex 27b.

Scheme 12. a) Oxalyl chloride, toluene, 608C, 69%; b) AgPF₄, CH₂Cl₂,

65%; c) [Pd(PPh₃)₄], CH₂Cl₂, RT, 56%; d) [Pd(PPh₃)₄], toluene, 1008C,

43%.

Scheme 13. Further Fischer-carbene complexes of Pd^IIformed by oxida-

tive insertion.

highly flexible in structural terms due to the ready accessi-

bility of the required precursor salts from simple benzoic

acid amides, thiocarbamates or dithiocarbamates, respective-

ly. Figures 13–18 show the structure of representative mem-

ꢀ

Figure 15. Molecular structure of complex 28b. The PF₆counterion is

omitted for clarity.

Figure 13. Molecular structure of complex 27a.

Figure 16. Molecular structure of complex 32.

bers of such Fischer carbenes of Pd^IIin the solid state. It is

interesting to note that compound 33 is the only cationic

complex prepared during this study which is cis- rather than

trans-configured.

types by oxidative addition suggested that the concept

should be applicable to other transition metals as well. In

contrast to our expectations, however, preliminary attempts

to replace [Pd(PPh₃)₄] by [Rh(Ph₃P)₃Cl], [RhCl(cod)]₂,

[RhCp(C₂H₄)₂], [CoCp(C₂H₄)₂], or [FeCp(CO)₂]₂essentially

Nickel–carbene complexes: The proven flexibility of the

new approach to palladium carbene complexes of different

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A. Fꢂrstner et al.

Despite these setbacks, the importance of nickel catalysts

for various types of bond forming reactions spurred further

efforts to prepare carbene complexes of this metal via oxi-

dative addition.^[41]After some experimentation it was found

that the use of [Ni(cod)₂] in combination with PPh₃

(2 equiv) in THF at ambient temperature led to clean con-

versions and allowed for the formation of a variety of cati-

onic nickel–diaminocarbene complexes in good to excellent

yields. The use of PEt₃instead of PPh₃works equally well,

suggesting that further variations of the accompanying phos-

phine ligands might be possible (Table 1, entry 3). Products

Table 1. Preparation of nickel-diaminocarbene complexes by oxidative

insertion into various amidinium salts. All reactions were performed in

THF at ambient temperature using [Ni(cod)₂] and PPh₃as the reagents

unless stated otherwise.

Figure 17. Molecular structure of the cis-configured complex 33. The

PF₆^ꢀcounterion is omitted for clarity.

Entry

Substrate

Product

Yield [%]

1

1a

37

38

39

86

2

3

1b

1a

62

78^[a]

4

18a

40

41

Figure 18. Molecular structure of complex 34.

met with failure. Particularly surprising was the fact that the

reaction of [Ni(PPh₃)₄] or [Ni(cod)₂] with 1 as a prototype

carbene source led to rather com-

plex mixtures under various experi-

mental conditions. The only product

that could be isolated in analytically

pure form was the imidazolinium

tetrachloronickelate salt 36, the

structure of which is shown in

Figure 19.

5

6

18b

21

41

42

50

64

[a] Using PEt₃/[Ni(cod)₂] as the reagent combination.

37–42 formed by this protocol are summarized in Table 1. In

several cases was it possible to grow crystals suitable for X-

ray analysis. The structures of representative complexes are

depicted in Figures 20–22.

Structural aspects: Several carbene complexes yielded crys-

tals suitable for single crystal structure determination. All of

them are distorted square-planar with root mean square de-

viations from planarity ranging from 0.005 to 0.068 ꢄ. Al-

though the square planar geometry allows for cis–trans iso-

merism, the neutral dichloro complexes invariably show cis

geometry placing one chlorine trans to the PPh₃ligand and

the other one trans to the carbene. In the series of charged

Figure 19. Molecular structure of the nickelate complex 36.

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Carbene Complexes

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0.1 ꢄ from an average of 2.344(16) ꢄ for those complexes

with two phosphine ligands trans to each other, to 2.259(8)

when a chlorine is trans to the phosphine. The metal–chlor-

ine distances are not affected significantly, the average is

2.358(12) ranging from 2.341 to 2.378 ꢄ. A much smaller

and statistically less significant influence on bond length is

observed for the palladium–carbene distance. This distance

is on average 1.990(15) ꢄ ranging from 1.969 to 2.023 ꢄ for

the 15 complexes where a chlorine is trans to the carbene,

and the one example 33 which has a phosphine trans to the

carbene where the Pd–C distance is 2.047(3) ꢄ. From the

nickel complexes, all of which have two PPh₃ligands in

trans orientation, no trends can be deduced. In line with the

results of previous crystallographic investigations of diami-

nocarbenes and metal complexes thereof, the bond angle N-

ꢀ

Figure 20. Molecular structure of the nickel complex 37. The PF₆coun-

terion is omitted for clarity.

C_carbene-X (X=N, O, S, C) is significantly widened in all

structures in which this element is not part of a cyclic motif;

likewise, complexes 16a,b bearing the heterocyclic carbene

with a six-membered backbone also feature such a rather

large bond angle. Selected data together with the character-

istic shifts of the carbene atoms in the ¹³C NMR spectra are

compiled in Table 2.

Table 2. Selected structural data and compilation of the ¹³C NMR shifts

of the carbene centers of all metal carbene complexes characterized by

X-ray crystallography.

Complex

M–C_carbene

[ꢄ]

N-C_carbene-X

[8]

Tilt angle

d_C

[8]^[a]

[C_carbene, ppm]

2a

9a

9b

11

12

13

16a

16b

19

22

23

27a

27b

28b

32

33

34

37

38

42

1.9805(18)

1.975(2)

1.9687(17)

1.971(3)

1.986(4)

1.981(2)

2.005(2)

2.005(4)

2.023(3)

1.9825(13)

2.003(5)

1.9791(11)

1.985(5)

1.998(3)

1.9937(12)

2.047(3)

1.975(2)

1.8650(17)

1.8626(14)

1.894(5)

109.70(16)

108.65(18)

108.95(15)

109.0(3)

109.6(3)

109.1(2)

120.1(2)

119.6(4)

122.3(3)

119.20(12)

121.6(5)

111.63(9)

113.8(3)

113.5(2)

122.44(11)

124.0(2)

121.8(2)

109.0(16)

109.85(13)

121.3(3)

87.87

84.79

78.94

86.39

87.86

78.77

90.00

81.06

80.85

84.87

82.45

89.31

82.84

74.93

80.24

81.29

87.93

85.91

81.81

194.9

193.2

190.0

194.5

195.4

195.0

187.4

187.7

193.8

201.3

198.8

204.8

228.7

230.3

232.4

235.1

226.4

197.1

197.0

199.9

ꢀ

Figure 21. Molecular structure of the nickel complex 38. The BF₄coun-

terion is omitted for clarity.

[a] Refers to the dihedral angle between the square plane defined by the

ligands around the metal and the plane of the carbene ligand formed by

N-C_carbene-X.

ꢀ

Figure 22. Molecular structure of the nickel complex 42. The PF₆coun-

terion omitted for clarity.

The crystal structures encompass both charged and neu-

tral complexes, but no significant differences in metal car-

bene distance are found. The average palladium–carbene

distance for the charged complexes is 1.998(21) ꢄ and for

neutral complexes 1.979(8) ꢄ, respectively. For individual

pairs of neutral/charged complexes it is observed that the

charged complex always has a slightly longer metal–carbene

distance (e.g. 3/trans-2a; 22/23; 33/32; 13/12).

complexes, the two PPh₃ligands are mutually trans to each

other except for 33 in which the two phosphines have a cis

arrangement (Figure 17).

For the palladium complexes a strong trans-effect is noted

ꢀ

which shortens the metal phosphorous bond by almost

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A. Fꢂrstner et al.

Although the carbene ligands encompass a wide variety

of different functional groups and steric demand, there is a

general tendency for the plane formed by N-C-(N,C,O,S) to

be rotated away from the square-planar arrangement of the

metal ligands. The dihedral angle between these two planes

ranges from 74.93 to 908 for the palladium complexes and is

between 81.81 and 89.938 for the nickel complexes.

This perpendicular arrangement would certainly be ex-

pected for the more bulky carbene ligands like the one in

complexes 10 and 11. However, it is interesting to speculate

whether there would be sufficient space for the bis(dimethyl-

amino)methylene ligand in 22 and 23 or the similar sized

carbene ligand in complex 16 to adopt a conformation plac-

ing the N-C-N plane more or less parallel to the metal coor-

dination plane. This orientation permits the overlap of the

empty p_porbital of the carbene with the 4d_z₂-orbital of palla-

dium. To achieve this conformation it would be necessary

Scheme 14. a) trans-2a (1 mol%), PhB(OH)₂, K₂CO₃, THF, reflux, 79%;

b) trans-2a (1 mol%), [(9-BBN)(OMe)(CꢁCMe)], THF, reflux, 82%

(GC).

ꢀ

for the triphenylphosphines to rotate around the Pd P bond

and to re-orient the phenyl rings. An analysis of the arrange-

ment of triphenylphosphines binding to tetra-coordinated

palladium in cis geometry to chlorine based on 170 crystal

structures reveals, however, that there is a clear preference

for a staggered orientation of the PPh₃group with respect to

moacetophenone 43a with PhB(OH)₂in the presence of

1 mol% of 2a afforded the expected product 45 in 79%

yield. Likewise, the borate formed in situ from 9-MeO-9-

BBN and NaCꢁCMe^[44]transferred its alkynyl unit with sim-

ilar ease to give product 44. Furthermore, this catalyst ef-

fected the Heck coupling^[43,45,46]of bromo- or iodobenzene

with butyl acrylate as well as the Buchwald-Hartwig amina-

tion^[47,48]of either bromobenzene or 2-chloropyridine with

morpholine in satisfactory yields (Scheme 15). Therefore

these prototype reactions were used to evaluate and com-

pare the performance of the different catalysts.

ꢀ

the Pd Cl bond. This becomes even more pronounced if

only those 40 structures are considered where the remaining

two palladium ligands are carbon and either another phos-

phorous or another chlorine atom (Figure 23). Based on this

preferred dihedral angle distribution it is reasonable to

assume that the phosphineꢁs phenyl rings exert a significant

directing influence on the orientation of the carbene.

Scheme 15. Model reactions to evaluate the catalytic performance of dif-

ferent metal carbene complexes; for the reaction conditions see Table 3.

Figure 23. Distribution of the C-P-Pd-Cl dihedral angles in complexes

with the extended substructure Ph₃P-Pd-(X,C,Cl)₃, where X is either

phosphorous or chlorine and the carbon atom may be any type of

carbon. The P-Pd-Cl as well as the P-Pd-C angles are restricted to values

between 75 and 1058.

As can be seen from the results compiled in Table 3, all

complexes investigated showed good to excellent activity in

the chosen test reactions. While this may not be surprising

for the palladium complexes bearing NHC- and related dia-

minocarbene ligands in view of the proven efficiency of such

species in various kinds of metal-catalyzed cross-couplings,

it is interesting to note that even prototype Fischer carbenes

such as 32 and 34 showed appreciable reactivity, although

they are likely less electron rich at the metal center than

their NHC counterparts (entries 41–46). Likewise, carbenes

with heteroelements other than nitrogen gave promising re-

sults (entries 30–40). This is particularly true for complex

22b incorporating a phenylthioether motif (entries 36–40).

In evaluating these data, it must be kept in mind that the

steric properties of all catalysts tested herein are almost cer-

Catalytic performance in cross-coupling reactions: Although

the main purpose of this study was the development of a

novel synthesis route for metal–carbene complexes rather

than the optimization of their catalytic properties, the small

library of compounds formed during this investigation was

screened in prototype cross-coupling reactions.

Preliminary experiments showed that the cationic Pd–

NHC complex 2a serves as active catalyst for Suzuki reac-

tions (Scheme 14).^[42,43]Specifically, cross-coupling of 4-bro-

1842

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www.chemeurj.org

Chem. Eur. J. 2005, 11, 1833 – 1853

Carbene Complexes

FULL PAPER

Table 3. Evaluation of the catalytic performance of various palladium–carbene complexes in prototype cross-

coupling reactions. All transformations were carried out by using 1 mol% of the metal complex. The yields

refer to GC data unless stated otherwise.

tainly not ideal, thus leaving

room for further optimiza-

tion.^[49]

The same holds true for the

novel nickel carbene com-

plexes which were found to

effect the Kumada–Corriu

cross-coupling^[43,50,51]of p-me-

Entry

Catalyst

Substrate

Suzuki [%]^[a]

Heck [%]^[b]

Amination^[c]

1

2

3

43a

47

48

79^[d]

86

84

100

4

5

6

7

43a

43c

46

89

88

thoxyphenylmagnesium

bro-

mide with chloro- or bromo-

benzene as well as 2-chloropyr-

idine (Table 4). Although small

amounts of 4,4’-dimethoxybi-

phenyl formed by homocou-

pling of the Grignard reagent

were invariably detected in the

crude mixtures (15–25%), the

desired products were obtained

in good yields in all cases in-

vestigated.

100

90

47

8

9

46

47

100

81

10

11

46

47

97

59

Conclusion

12

13

14

43a

46

47

93

100

51

Oxidative

insertion

of

[Pd(PPh₃)₄] or [Ni(cod)₂]/PPh₃

ꢀ

into the C Cl bond of 2-chloro-

amidinium and related salts

constitutes a fairly general and

highly flexible entry into neu-

tral as well as cationic diami-

nocarbene complexes of Pd^II

and Ni^II, respectively. This ap-

proach is complementary to

existing methodology which

relies on metathetic ligand ex-

change reactions without alter-

ing the oxidation state of the

central metal, and therefore

provides access to ligand sets

that are difficult to prepare

otherwise. Moreover, it can

also be applied to the forma-

tion of Fischer-carbene com-

plexes of nickel and palladium.

A representative subset of the

products formed by this novel

route was characterized by X-

ray crystallography and was

found to exhibit appreciable

catalytic activity in Suzuki-,

Heck-, Kumada- and Buch-

wald–Hartwig reactions. In

view of the ready availability

of the required amidinium salts

(even in enantiopure form)

from simple urea or thiourea

15

16

46

47

96

79

17

18

46

47

98

19

20

46

47

87

72

21

22

46

47

91

88

23

24

46

47

92

77

25

26

27

46

47

48

80

75

89

100

28

29

46

47

82

56

Chem. Eur. J. 2005, 11, 1833 – 1853

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1843

A. Fꢂrstner et al.

Table 3. (Continued)

Entry

flash chromatography (hexane/ethyl

acetate 6:1) to give thiourea 5 as a

white solid (1.02 g, 4.67 mmol, 82%).

¹H NMR (400 MHz, CDCl₃): d=

7.55–7.53 (m, 2H), 7.41–7.36 (m, 2H),

7.24–7.20 (m, 1H), 4.18–4.06 (m, 3H),

3.99–3.96 (m, 1H), 3.48–3.42 (m, 1H),

2.21–2.12 (m, 2H), 2.06–1.94 (m, 1H),

Catalyst

Substrate

Suzuki [%]^[a]

Heck [%]^[b]

Amination^[c]

30

31

32

33

43b

43a

47

83

81

82

100

48

1.63–1.53

(m,

1H);

¹³C NMR

34

35

43b

43a

72

69

(100 MHz, CDCl₃): d=184.2 (C),

141.1 (C), 129.1 (CH), 126.4 (CH),

124.7 (CH), 59.8 (CH), 55.6 (CH₂),

48.2 (CH₂), 31.6 (CH₂), 25.6 (CH₂);

IR (KAP): n˜ =3102, 3064, 3037, 2965,

2945, 2913, 2877, 1594, 1581, 1498,

1475, 1436, 1396, 1362, 1332, 1314,

1295, 1259, 1183, 1165, 1081, 1047,

945, 900, 878, 830, 764, 693, 644, 631,

567, 545, 492 cm^ꢀ1; MS (EI): m/z (%):

218 (100) [M ⁺], 217 (90), 189 (5), 185

(3), 177 (4), 175 (3), 151 (2), 145 (3),

136 (7), 135 (16), 132 (6), 130 (3), 117

(5), 109 (5), 104 (11), 77 (29), 55 (10),

41 (10); HRMS: calcd for C₁₂H₁₄N₂S:

218.0878, found: 218.0877; elemental

analysis calcd (%) for: C 66.02, H

6.46, N 12.83; found: C 66.21, H 6.40,

N 12.69.

36

37

38

39

40

43b

43a

43c

47

82

78

81^[e]

92

47

48

41

42

43

44

43b

43a

47

68

55

73

100

48

45

46

43b

43a

80

78

General procedure for the conversion

of thioureas into amidinium chlori-

des:^[31c]Oxalyl chloride (1.2 equiv)

was added to a solution of the thiour-

ea in anhydrous toluene (5 mL per

mmol of thiourea). The resulting

bright yellow solution was stirred for

[a] Unless stated otherwise, the Suzuki reactions were performed in refluxing THF using K₂CO₃as the base.

[b] Heck reactions were performed in NMP at 1208C for 16 h using Cs₂CO₃as the base. [c] The amination re-

actions were performed in DME with NaO(tBu) as the base at ambient temperature with substrate 48 and at

708C with substrate 47. [d] Isolated yield. [e] In toluene at 1208C.

16 h at 608C, causing the precipitation of a pale brown solid. This precipi-

tate was allowed to settle, the solution was siphoned off, and the solid

was repeatedly washed with Et₂O. The following compounds were pre-

pared according to this general procedure.

precursors, it is reasonable to expect that this method might

find broader applications in the future.

Compound 6a (X=Cl): colorless solid (96 mg, 80%); ¹H NMR

(400 MHz, CD₂Cl₂): d=7.77–7.72 (m, 2H), 7.51–7.43 (m, 3H), 4.82–4.61

(m, 3H), 4.20–4.13 (m, 1H), 3.67–3.61 (m, 1H), 2.76–2.66 (m, 1H), 2.51–

2.43 (m, 1H), 2.31–2.15 (m, 2H); ¹³C NMR (100 MHz, CD₂Cl₂): d=156.6

(C), 135.5 (C), 130.2 (CH), 130.0 (CH), 126.4 (CH), 63.9 (CH), 59.5

(CH₂), 47.9 (CH₂), 30.1 (CH₂), 26.4 (CH₂); IR (KBr): n˜ =3057, 2963,

2947, 2873, 1599, 1581, 1503, 1482, 1448, 1412, 1365, 1328, 1318, 1282,

1218, 1137, 1120, 1075, 1043, 1024, 995, 912, 898, 877, 816, 770, 752, 693,

628, 606, 562, 535, 511 cm^ꢀ1; MS (ESI-pos., CH₂Cl₂): m/z: 221.2 [M ⁺

ꢀCl]; elemental analysis calcd (%) for: C 56.00, H 5.35, N 10.96; found:

C 56.05, H 5.49, N 10.89.

Compound 7a (X=Cl): colorless solid (529 mg, 82%); ¹H NMR

(400 MHz, CD₂Cl₂): d=3.94–3.91 (m, 2H), 3.68–3.54 (m, 4H), 2.26–2.23

(m, 2H), 1.97–1.92 (m, 2H), 1.75–1.66 (m, 2H), 1.56 (ddd, J=13.0, 11.4,

6.3 Hz, 2H), 1.50–1.38 (m, 4H), 0.96 (s, 18H); ¹³C NMR (100 MHz,

CD₂Cl₂): d=158.1, 67.9, 43.7, 41.2, 29.9, 28.9, 27.5, 23.7; IR (KBr): n˜ =

3000, 2868, 1578, 1466, 1419, 1383, 1366, 1328, 1309, 1269, 1250, 1176,

1112, 1065, 1022, 966, 912, 834, 757, 645, 518; MS (ESI-pos., CH₂Cl₂): m/z:

327.3 [M ⁺ꢀCl]; elemental analysis calcd (%) for: C 62.80, H 9.98, N

7.71; found: C 62.63, H 9.98, N 7.74.

Experimental Section

General: All reactions were carried out under Ar in flame-dried glass-

ware. The solvents used were purified by distillation over the drying

agents indicated and were transferred under Ar: THF, Et₂O (Mg/anthra-

cene), CH₂Cl₂(P₄O₁₀), MeCN, Et₃N (CaH₂), MeOH (Mg), DMF, DMA

(Desmodur, dibutyltin dilaurate), hexane, toluene (Na/K). Flash chroma-

tography: Merck silica gel 60 (230–400 mesh). NMR: Spectra were re-

corded on a Bruker DPX 300, AV 400, or DMX 600 spectrometer in the

solvents indicated; chemical shifts (d) are given in ppm relative to TMS,

coupling constants (J) in Hz. The solvent signals were used as references

and the chemical shifts converted to the TMS scale (CDCl₃: d_C

77.0 ppm; residual CHCl₃in CDCl₃: d_H7.24 ppm; CD₂Cl₂: d_C

=

53.8 ppm; residual CH₂Cl₂in CD₂Cl₂: d_H= 5.32 ppm). IR: Nicolet FT-

7199 spectrometer, wave numbers (n˜) in cm^ꢀ1. MS (EI): Finnigan MAT

8200 (70 eV), ESI-MS: Finnigan MAT 95, accurate mass determinations:

Bruker APEX III FT-MS (7 T magnet). Melting points: Bꢂchi melting

point apparatus B-540 (corrected). Elemental analyses: H. Kolbe, Mꢂl-

heim/Ruhr. All commercially available compounds (Fluka, Lancaster, Al-

drich) were used as received.

Compound 21a:^[52]colorless solid (1.16 g, 90%); ¹H NMR (400 MHz,

CD₂Cl₂): d=3.47 (s, 12H); ¹³C NMR (100 MHz, CD₂Cl₂): d=159.0 (C),

44.8 (CH₃); IR (KBr): n˜ =3442, 3023, 2945, 2434, 2171, 1653, 1544, 1506,

1467, 1404, 1301, 1260, 1170, 1118, 1064, 1038, 939, 898, 872, 719, 638,

562 cm^ꢀ1; MS (ESI-pos.): m/z: 135.1 [M ⁺ꢀCl]; elemental analysis calcd

(%) for: C 35.11, H 7.07, N 16.38; found: C 35.25, H 7.15, N 16.29.

Starting materials

Compound 5: Thiophosgene (0.48 mL, 6.24 mmol) was slowly added to a

solution of diamine 4 (1.0 g, 5.67 mmol) in CH₂Cl₂(25 mL) and Et₃N

(1.6 mL, 11.34 mmol) and the resulting mixture was stirred for 3 h at am-

bient temperature. For work-up, the mixture was diluted with CH₂Cl₂

and the reaction was quenched with water. The aqueous phase was re-

peatedly extracted with CH₂Cl₂, the combined organic layers were dried

(Na₂SO₄), the solvent was evaporated and the residue was purified by

General procedure for the conversion of ureas into amidinium chlori-

des:^[31c]Oxalyl chloride (1.2 equiv) was added to a solution of the urea in

anhydrous CCl₄(2 mL per mmol). The resulting bright yellow solution

1844

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Chem. Eur. J. 2005, 11, 1833 – 1853

Carbene Complexes

FULL PAPER

Table 4. Kumada cross-coupling reactions catalyzed by different nickel–carbene complexes. All reactions were

mental analysis calcd (%) for: C

performed in THF at ambient temperature for 18 h, by using 3 mol% of the catalyst; the yields refer to GC

data.

49.11, H 5.04, N 6.36; found C 48.98,

H 5.11, N 6.43.

Compound 25b (X=S):^[55]Prepared

in toluene as the solvent; colorless

solid (202 mg, 85%); ¹H NMR

(400 MHz, CD₂Cl₂): d=7.80–7.77 (m,

2H), 7.66–7.62 (m, 1H), 7.57–7.52

(m, 2H), 4.02 (s, 6H); ¹³C NMR

(100 MHz, CD₂Cl₂): d=177.8 (C),

136.5 (CH), 133.1 (CH), 130.7 (CH),

124.8 (C), 49.1 (CH₃); IR (KBr): n˜ =

3050, 2995, 2930, 1667, 1596, 1476,

1441, 1405, 1365, 1311, 1257, 1246,

1178, 1102, 1087, 1070, 1023, 990, 909,

872, 750, 708, 687, 653, 548, 525,

504 cm^ꢀ1; MS (ESI-pos.): m/z: 200.2

[M ⁺ꢀCl]; elemental analysis calcd

(%) for: C 45.77, H 4.69, N 5.93;

found: C 45.70, H 4.63, N 6.04.

Entry

Catalyst

Substrate

Yield [%]

1

2

3

47

53

48

70

69

78

4

5

6

47

53

48

61

69

71

Compound 30: Prepared in toluene

as the solvent; colorless solid

(573 mg, 69%); ¹H NMR (400 MHz,

CD₂Cl₂): d=7.86–7.82 (m, 2H), 7.14–

7.10 (m, 2H), 4.87–4.79 (m, 2H), 3.91

(s, 3H), 1.83 (d, J=7.0 Hz, 6H), 1.61

7

8

9

47

53

48

81

77

76

(d,

J=6.6 Hz,

6H);

¹³C NMR

(100 MHz, CD₂Cl₂): d=173.4 (C),

164.7 (C), 131.3 (CH), 124.5 (C),

115.0 (CH), 65.4 (CH₃), 58.8 (CH),

56.1 (CH), 20.3 (CH₃), 20.2 (CH₃);

IR (KBr): n˜ =3085, 3014, 2972, 2938,

2877, 2841, 1593, 1571, 1510, 1460,

1438, 1379, 1369, 1339, 1308, 1268,

1244, 1182, 1126, 1016, 894, 852, 843,

805, 773, 724, 689, 627, 605, 555, 535,

507 cm^ꢀ1; MS (ESI-pos.): m/z: 254.2

[M ⁺ꢀCl]; elemental analysis calcd

(%) for: C 57.94, H 7.29, N 4.83;

found: C 57.76, H 7.39, N 4.81.

10

11

12

47

53

48

80

77

78

13

14

15

47

53

48

67

61

74

was stirred for 16 h at 608C under argon, causing the precipitation of a

white solid. This precipitate was allowed to settle, the solution was si-

phoned off, and the solid was repeatedly washed with Et₂O. The follow-

ing compounds were prepared according to this procedure:

Compound 8a (X=Cl):^[53]colorless solid (356 mg, 60%); ¹H NMR

(400 MHz, CD₂Cl₂): d=7.58–7.55 (m, 2H), 7.45–7.43 (m, 3H), 7.34–7.31

(m, 3H), 7.15–7.12 (m, 2H), 5.29 (s, 1H), 4.05 (s, 1H), 3.16 (s, 3H), 2.62

(s, 3H); ¹³C NMR (100 MHz, CD₂Cl₂): d=158.1 (C), 138.3 (C), 133.1 (C),

130.4 (CH), 129.7 (CH), 128.9 (CH), 128.9 (CH), 128.4 (CH), 127.5

(CH), 75.2 (CH), 70.4 (CH), 34.0 (CH₃), 29.9 (CH₃); IR (KBr): n˜ =3389,

3061, 3026, 3004, 2945, 2865, 1615, 1586, 1482, 1455, 1434, 1409, 1389,

1359, 1307, 1284, 1251, 1195, 1149, 1078, 1029, 1018, 835, 777, 762, 711,

634, 615, 583, 554, 505, 473 cm^ꢀ1; MS (ESI-pos.): m/z: 285.1 [M ⁺ꢀCl].

Representative procedure for the formation of hexafluorophosphate

salts—Compound 7b (X=PF₆): AgPF₆(147 mg, 0.58 mmol) was added

to a solution of chloride salt 7a (X=Cl, 210 mg, 0.58 mmol) in CH₂Cl₂

(4 mL) and the resulting suspension was stirred for 1 h at ambient tem-

perature under argon. The mixture was filtered and the solvent was

evaporated to give the corresponding hexafluorophosphate salt 7b in an-

alytically pure form (219 mg, 79%). ¹H NMR (400 MHz, CD₂Cl₂): d=

3.63–3.60 (m, 2H), 3.58–3.52 (m, 4H), 2.26–2.23 (m, 2H), 2.03–1.98 (m,

2H), 1.63–1.60 (m, 2H), 1.59–1.51 (m, 2H), 1.47–1.36 (m, 4H), 0.96 (s,

18H); ¹³C NMR (100 MHz, CD₂Cl₂): d=157.8 (C), 67.7 (CH), 43.3

(CH₂), 40.9 (CH₂), 29.9 (C), 28.8 (CH₃), 27.4 (CH₂), 23.7 (CH₂);

³¹P NMR (121 MHz, CD₂Cl₂): d=ꢀ143.9 (hept., J(P,F)=711 Hz); IR

(KBr): n˜ =2950, 2873, 1571, 1494, 1474, 1458, 1444, 1366, 1328, 1313,

1271, 1253, 1178, 1165, 1110, 1054, 999, 969, 912, 877, 839, 778, 652, 557,

485 cm^ꢀ1; MS (ESI-pos.): m/z: 327.3 [M ⁺ꢀPF₆]; elemental analysis calcd

(%) for: C 48.25, H 7.67, N 5.92; found: C 48.31, H 7.74, N 5.96.

Compound 15a (X=Cl): colorless solid (423 mg, 59%); ¹H NMR

(400 MHz, CD₂Cl₂): d=3.86 (dt, J=5.9, 1.2 Hz, 4H), 3.40 (d, J=1.2 Hz,

6H), 2.2 (dquint., J=5.9, 1.4 Hz, 2H); ¹³C NMR (100 MHz, CD₂Cl₂): d=

153.0 (C), 51.0 (CH₂), 43.2 (CH₃), 19.4 (CH₂); IR (KAP): n˜ =2944, 2874,

2363, 2059, 1648, 1508, 1445, 1411, 1364, 1324, 1235, 1123, 1033, 863, 844,

756, 624, 565 cm^ꢀ1; MS (ESI-pos.): m/z: 147.2 [M ⁺ꢀCl]; elemental analy-

sis calcd (%) for: C 39.36, H 6.61, N 15.30; found: C 39.37, H 6.68, N

15.24.

Compound 25a (X=O):^[54]Prepared in toluene as the solvent; colorless

solid (249 mg, 91%); ¹H NMR (400 MHz, CD₂Cl₂): d=7.74–7.70 (m,

2H), 7.49–7.39 (m, 3H), 3.75 (s, 6H); ¹³C NMR (100 MHz, CD₂Cl₂): d=

161.7 (C), 153.0 (C), 130.4 (CH), 128.9 (CH), 121.7 (CH), 44.0 (CH₃); IR

(KBr): n˜ =3054, 3019, 2943, 1723, 1664, 1586, 1533, 1488, 1457, 1389,

1326, 1247, 1208, 1170, 1070, 1026, 939, 915, 845, 827, 814, 770, 752, 691,

663, 637, 615, 603, 502 cm^ꢀ1; MS (ESI-pos.): m/z: 184.2 [M ⁺ꢀCl]; ele-

The following compounds were prepared analogously:

Compound 6b (X=PF₆): pale brown solid (203 mg, 71%); ¹H NMR

(400 MHz, CD₂Cl₂): d=7.57–7.49 (m, 3H), 7.44–7.41 (m, 2H), 4.78–4.69

(m, 1H), 4.54 (t, J=11.0 Hz, 1H), 4.39 (dd, J=11.1, 8.9 Hz, 1H), 3.93–

3.86 (m, 1H), 3.72 (dt, J=9.6, 2.9 Hz, 1H), 2.48–2.37 (m, 2H), 2.32–2.19

(m, 1H), 2.17–2.06 (m, 1H); ¹³C NMR (100 MHz, CD₂Cl₂): d=156.0 (C),

134.8 (C), 130.6 (CH), 130.4 (CH), 125.5 (CH), 68.7 (CH), 58.3 (CH₂),

47.4 (CH₂), 30.5 (CH₂), 25.7 (CH₂); ³¹P NMR (121 MHz, CD₂Cl₂): d=

ꢀ143.8 (hept., J(P,F)=711 Hz); IR (KBr): n˜ = 3071, 2964, 2883, 1604,

1590, 1507, 1490, 1471, 1451, 1367, 1333, 1298, 1285, 1223, 1140, 1047,

1027, 833, 772, 696, 639, 608, 558, 536 cm^ꢀ1; MS (ESI-pos.): m/z: 221.0

Chem. Eur. J. 2005, 11, 1833 – 1853

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ꢃ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

1845

A. Fꢂrstner et al.

[M ⁺ꢀPF₆]; elemental analysis calcd (%) for: C 39.31, H 3.85, N 7.64;

from CH₂Cl₂to precipitate impurities. After filtration, crystallization of

the product was induced by slowly diffusing pentane into the CH₂Cl₂so-

lution to afford complex 10 as a yellow solid (183 mg, 63%). ¹H NMR

(400 MHz, CD₂Cl₂): d=7.65–7.58 (m, 18H), 7.54–7.50 (m, 12H), 3.67–

3.59 (m, 2H), 2.88–2.80 (m, 2H), 2.00 (br, 2H), 1.70 (d, J=6.1 Hz, 4H),

0.97–0.86 (m, 8H), 0.74 (s, 18H); ¹³C NMR (100 MHz, CD₂Cl₂): d=195.0

(C), 134.7 (CH), 132.2 (CH), 130.6 (C), 129.2 (t, J(C,P)=5.2 Hz, CH),

68.6 (CH), 47.2 (CH₂), 41.5 (CH₂), 29.6 (CH₂), 28.7 (CH₃), 28.6 (C), 23.7

(CH₂); ³¹P NMR (121 MHz, CD₂Cl₂): d=23.1, ꢀ143.9 (hept., J(P,F)=

711 Hz); IR (KBr): n˜ =3056, 2954, 2866, 1585, 1573, 1482, 1436, 1396,

1367, 1324, 1310, 1260, 1187, 1162, 1093, 1027, 1000, 873, 839, 748, 695,

637, 617, 557, 520, 495 cm^ꢀ1; MS (ESI-pos.): m/z: 957.5 [M ⁺ꢀPF₆]; ele-

mental analysis calcd (%) for: C 59.84, H 6.03, N 2.54; found: C 59.73, H

5.95, N 2.48.

found: C 39.46, H 3.81, N 7.60.

Compound 8b (X=PF₆): colorless solid (121 mg, 70%); ¹H NMR

(400 MHz, CD₂Cl₂): d=7.50–7.46 (m, 3H), 7.40–7.36 (m, 3H), 7.34–7.32

(m, 2H), 7.20–7.17 (m, 2H), 5.08 (s, 1H), 4.30 (s, 1H), 3.11 (s, 3H), 2.75

(s, 3H); ¹³C NMR (100 MHz, CD₂Cl₂): d=157.0 (C), 137.6 (C), 132.8 (C),

130.7 (CH), 130.0 (CH), 129.1 (CH), 128.8 (CH), 128.2 (CH), 127.4

(CH), 74.8 (CH), 70.6 (CH), 33.6 (CH₃), 29.9 (CH₃); ³¹P NMR (121 MHz,

CD₂Cl₂): d=ꢀ143.7 (hept., J(P,F)=711 Hz); IR (KBr): n˜ =3066, 3035,

2950, 2881, 2813, 1697, 1655, 1619, 1587, 1519, 1498, 1457, 1413, 1358,

1308, 1279, 1235, 1214, 1144, 1081, 1030, 1004, 971, 839, 759, 703, 656,

635, 588, 557 cm^ꢀ1; MS (ESI-pos.): m/z: 285.2 [M ⁺ꢀPF₆]; elemental anal-

ysis calcd (%) for: C 47.40, H 4.21, N 6.50; found: C 47.56, H 4.34, N

6.63.

Compound 15b (X=PF₆):^[56]colorless solid (157 mg, 90%); ¹H NMR

(400 MHz, CD₂Cl₂): d=3.67 (t, J=6.0 Hz, 4H), 3.37 (s, 6H), 2.21 (quint.,

J=6.0 Hz, 2H); ¹³C NMR (100 MHz, CD₂Cl₂): d=153.0 (C), 53.0 (CH₂),

43.0 (CH₃), 19.1 (CH₂); ³¹P NMR (121 MHz, CD₂Cl₂): d=ꢀ143.9 (hept.,

J(P,F)=711 Hz); IR (KBr): n˜ =2956, 2892, 2263, 1651, 1511, 1452, 1416,

1368, 1326, 1306, 1239, 1129, 1057, 1037, 833, 742, 635, 610, 558, 494,

481 cm^ꢀ1; MS (ESI-pos.): m/z: 147.1 [M ⁺ꢀPF₆]; elemental analysis calcd

(%) for: C 24.63, H 4.13, N 9.57; found: C 24.57, H 4.18, N 9.48.

Compound 21b (X=PF₆):^[57]colorless solid (224 mg, 91%); ¹H NMR

(400 MHz, CD₂Cl₂): d=3.33 (s, 12H); ¹³C NMR (100 MHz, CD₂Cl₂): d=

159.9 (C), 44.3 (CH₃); ³¹P NMR (121 MHz, CD₂Cl₂): d=ꢀ144.0 (hept.,

J(P,F)=711 Hz); IR (KBr): n˜ = 2960, 2928, 1655, 1508, 1473, 1408, 1395,

1263, 1179, 1122, 1064, 1005, 836, 645, 617, 557 cm^ꢀ1; MS (ESI-pos.): m/z:

135.0 [M ⁺ꢀPF₆]; elemental analysis calcd (%) for: C 21.40, H 4.31, N

9.98; found: C 21.36, H 4.27, N 10.06.

Compound 26a (X=O): colorless oil (111 mg, 75%); ¹H NMR

(400 MHz, CD₂Cl₂): d=7.57–7.48 (m, 3H), 7.21–7.16 (m, 2H), 3.71 (s,

3H), 3.68 (s, 3H); ¹³C NMR (100 MHz, CD₂Cl₂): d=161.7 (C), 152.6 (C),

129.6 (CH), 125.3 (CH), 121.0 (CH), 44.7 (CH₃), 42.9 (CH₃); ³¹P NMR

(121 MHz, CD₂Cl₂): d=ꢀ143.9 (hept., J(P,F)=711 Hz); IR (KBr): n˜ =

3063, 2955, 2917, 2849, 2645, 1668, 1602, 1585, 1490, 1462, 1418, 1392,

1332, 1248, 1210, 1172, 1144, 1070, 1030, 1005, 939, 838, 815, 766, 688,

664, 630, 608, 558, 499, 467 cm^ꢀ1; MS (ESI-pos.): m/z: 184.1 [M ⁺ꢀPF₆];

elemental analysis calcd (%) for: C 32.80, H 3.36, N 4.25; found: C 32.74,

H 3.43, N 4.16.

Compound 26b (X=S): pale yellow solid (191 mg, 86%); ¹H NMR

(400 MHz, CD₂Cl₂): d=7.69–7.65 (m, 3H), 7.61–7.57 (m, 2H), 3.81 (s,

6H); ¹³C NMR (100 MHz, CD₂Cl₂): d=176.7 (C), 136.5 (CH), 133.6

(CH), 130.3 (CH), 124.2 (C), 49.0 (CH₃); ³¹P NMR (121 MHz, CD₂Cl₂):

d=ꢀ143.9 (hept., J(P,F)=711 Hz); IR (KBr): n˜ =3060, 2919, 2849, 1666,

1605, 1477, 1446, 1411, 1366, 1335, 1261, 1236, 1137, 1104, 1089, 1059,

1026, 990, 879, 838, 758, 707, 688, 657, 558, 525, 505, 494 cm^ꢀ1; MS (ESI-

pos.): m/z: 200.2 [M ⁺ꢀPF₆]; elemental analysis calcd (%) for: C 31.27, H

3.21, N 4.05; found: C 31.21, H 3.16, N 3.88.

Compound 31: colorless solid (176 mg, 65%); ¹H NMR (400 MHz,

CD₂Cl₂): d=7.63–7.59 (m, 2H), 7.16–7.12 (m, 2H), 4.87 (hept., J=

6.6 Hz, 1H), 4.61 (hept., J=7.1 Hz, 1H), 3.93 (s, 3H), 1.79 (d, J=7.0 Hz,

6H), 1.54 (d, J=6.6 Hz, 6H); ¹³C NMR (100 MHz, CD₂Cl₂): d=165.6

(C), 161.9 (C), 131.1 (CH), 128.2 (C), 114.5 (CH), 65.7 (CH₃), 56.3 (CH),

55.7 (CH), 20.2 (CH₃), 20.1 (CH₃); ³¹P NMR (121 MHz, CD₂Cl₂): d=

ꢀ143.8 (hept., J(P,F)=710.6 Hz); IR (KBr): n=2975, 2939, 2848, 1625,

1610, 1576, 1546, 1511, 1470, 1443, 1371, 1339, 1302, 1256, 1213, 1180,

1161, 1107, 1027, 925, 887, 842, 819, 801, 767, 733, 596, 558, 491 cm^ꢀ1; MS

(ESI-pos): m/z: 254.2 [M ⁺ꢀPF₆], 212.2 [M⁺ꢀPF₆ꢀiPr]; elemental analy-

sis calcd (%) for: C 42.06, H 5.30, N 3.50; found: C 42.16, H 5.26, N 3.41.

Complex trans-2a^[24]and the following were prepared analogously.

Compound 12: pale yellow solid (151 mg, 43%); ¹H NMR (400 MHz,

CD₂Cl₂): d=7.73–7.63 (m, 18H), 7.59–7.55 (m, 12H), 7.32–7.28 (m, 2H),

7.22–7.18 (m, 4H), 6.24–6.22 (m, 4H), 3.82 (s, 2H), 3.01 (s, 6H);

¹³C NMR (100 MHz, CD₂Cl₂): d=195.4 (C), 134.6 (t, J(C,P)=6.1 Hz,

CH), 132.1 (CH), 131.9 (CH), 129.8 (C), 129.7 (d, J(C,P)=22.2 Hz, C),

129.4 (t, J(C,P)=5.2 Hz, CH), 129.2 (CH), 127.8 (CH), 76.6 (CH), 36.3

(CH₃); ³¹P NMR (121 MHz, CD₂Cl₂): d=24.4, ꢀ143.9 (hept., J(P,F)=

711 Hz); IR (KBr): n˜ =3056, 2914, 1586, 1573, 1523, 1496, 1483, 1455,

1436, 1395, 1352, 1310, 1273, 1230, 1189, 1162, 1095, 1029, 1000, 960, 911,

875, 838, 750, 695, 642, 616, 594, 558, 521, 494 cm^ꢀ1; MS (ESI-pos.): m/z:

915.25 [M ⁺ꢀPF₆]; elemental analysis calcd (%) for: C 59.95, H 4.56, N

2.64; found: C 59.90, H 4.48, N 2.56.

Compound 16b (X=PF₆): pale yellow solid (301 mg, 61%); ¹H NMR

(400 MHz, CD₂Cl₂): d=7.74–7.69 (m, 12H), 7.60–7.50 (m, 18H), 3.31 (s,

6H), 2.25 (t, J=6.1 Hz, 4H), 0.91 (quint., J=6.0 Hz, 2H); ¹³C NMR

(100 MHz, CD₂Cl₂): d=187.7 (C), 134.4 (t, J(C,P)=6.2 Hz, CH), 131.9

(CH), 129.5 (d, J(C,P)=25.0 Hz, C_q), 129.1 (t, J(C,P)=5.1 Hz, CH), 46.1

(CH₂), 45.9 (CH₃), 18.0 (CH₂); ³¹P NMR (121 MHz, CD₂Cl₂): d=21.9,

ꢀ143.9 (hept., J(P,F)=711 Hz); IR (KBr): n˜ =3047, 2952, 2915, 2875,

1579, 1494, 1482, 1435, 1406, 1361, 1321, 1265, 1240, 1220, 1188, 1159,

1095, 1027, 999, 925, 837, 764, 748, 708, 695, 619, 599, 558, 520, 494 cm^ꢀ1

;

MS (ESI-pos.): m/z: 779.2 [M ⁺ꢀPF₆]; elemental analysis calcd (%) for:

C 54.62, H 4.58, N 12.34; found: C 54.58, H 4.63, N 12.36.

Compound 19: pale yellow solid (139 mg, 50%); ¹H NMR (400 MHz,

CD₂Cl₂): d=7.60–7.49 (m, 30H), 4.03 (t, J=5.4 Hz, 4H), 2.21 (t, J=

4.8 Hz, 4H), 1.39 (quint., J=5.4 Hz, 4H), 1.20 (quint., J = 5.5 Hz, 8H);

¹³C NMR (100 MHz, CD₂Cl₂): d=193.8 (C), 134.5 (CH), 131.9 (CH),

129.4 (C), 129.2 (t, J(C,P)=5.4 Hz, CH), 57.0 (CH₂), 24.4 (CH₂), 23.3

(CH₂); ³¹P NMR (121 MHz, CD₂Cl₂): d=24.2, ꢀ143.9 (hept., J(P,F)=

710.6 Hz); IR (KBr): n˜ =3057, 2947, 2853, 1587, 1573, 1538, 1481, 1436,

1409, 1346, 1321, 1281, 1259, 1244, 1188, 1161, 1130, 1095, 999, 838, 790,

746, 705, 693, 602, 557, 520, 498 cm^ꢀ1; MS (ESI-pos.): m/z: 847.3 [M ⁺

ꢀPF₆]; elemental analysis calcd (%) for: C 56.92, H 5.08, N 2.82; found:

C 57.08, H 5.03, N 2.75.

Compound 23: pale yellow solid (255 mg, 48%); ¹H NMR (400 MHz,

CD₂Cl₂): d=7.70–7.66 (m, 12H), 7.60–7.50 (m, 18H), 3.43 (s, 6H), 2.03

(s, 6H); ¹³C NMR (100 MHz, CD₂Cl₂): d=198.8 (C), 134.4 (t, J(C,P)=

6.2 Hz, CH), 132.0 (CH), 129.6 (d, J(C,P)=25.0 Hz, C), 129.3 (t, J(C,P)=

5.2 Hz, CH), 47.1 (CH₃), 42.9 (CH₃); ³¹P NMR (121 MHz, CD₂Cl₂): d=

22.4, ꢀ143.9 (hept., J(P,F)=710.6 Hz); IR (KBr): n˜ =3051, 2960, 2922,

1656, 1564, 1496, 1482, 1435, 1405, 1389, 1314, 1267, 1189, 1159, 1095,

1052, 1027, 999, 918, 836, 747, 693, 611, 558, 521, 493 cm^ꢀ1; MS (ESI-

pos.): m/z: 767.3 [M ⁺ꢀPF₆]; elemental analysis calcd (%) for: C 54.02, H

4.64, N 12.50; found: C 54.12, H 4.58, N 12.57.

Compound 28a (X=O): yellow solid (110 mg, 30%); ¹H NMR

(400 MHz, CD₂Cl₂): d=7.68–7.58 (m, 7H), 7.54–7.47 (m, 12H), 7.44–7.39

(m, 12H), 7.20–7.15 (m, 2H), 6.84–6.81 (m, 2H), 3.18 (s, 3H), 2.57 (s,

3H); ¹³C NMR (75 MHz, CD₂Cl₂): d=207.5 (C), 153.2 (C), 134.3 (t,

J(C,P)=5.8 Hz, CH), 132.2 (CH), 130.2 (CH), 129.3 (t, J(C,P)=5.3 Hz,

CH), 128.5 (C), 128.1 (CH), 120.4 (CH), 44.5 (CH₃), 38.8 (CH₃);

³¹P NMR (121 MHz, CD₂Cl₂): d=21.4, ꢀ143.9 (hept., J(P,F)=711 Hz);

IR (KBr): n˜ =3057, 1598, 1574, 1482, 1435, 1347, 1308, 1266, 1226, 1156,

1095, 1026, 999, 841, 770, 751, 694, 606, 558, 521, 496 cm^ꢀ1; MS (ESI-

Representative procedure for the preparation of palladium complexes by

oxidative insertion into amidinium hexafluorophosphate salts—Com-

pound 10: A suspension of the hexafluorophosphate salt 7b (X=PF₆,

129 mg, 0.27 mmol) and [Pd(PPh₃)₄] (312 mg, 0.27 mmol) in toluene

(20 mL) was stirred under argon for 2 h at 1008C. After cooling, the sol-

vent was removed in vacuo, the waxy residue was suspended in pentane

and stirred for 1 h at ambient temperature to form a fine powder. The

pentane was discarded and the residue was extracted with pentane to

remove the remaining PPh₃. The crude product was then recrystallized

1846

ꢃ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

Chem. Eur. J. 2005, 11, 1833 – 1853

Carbene Complexes

FULL PAPER

pos.): m/z: 814.1 [M ⁺ꢀPF₆], 553.9 [M ⁺ꢀPF₆ꢀPPh₃]; elemental analysis

n˜ =3058, 2954, 2918, 2881, 2850, 1598, 1586, 1574, 1521, 1494, 1482, 1471,

calcd (%) for: C 56.27, H 4.30, N 1.46; found: C 56.16, H 4.12, N 1.36.

1458, 1436, 1413, 1370, 1325, 1301, 1259, 1185, 1119, 1094, 1072, 1028,

998, 922, 877, 840, 757, 746, 734, 697, 625, 594, 558, 542, 517, 497 cm^ꢀ1

;

Compound 28b (X=S): colorless solid (116 mg, 24%); ¹H NMR

(400 MHz, CD₂Cl₂): d=7.69–7.48 (m, 31H), 7.30–7.25 (m, 4H), 3.41 (s,

3H), 2.63 (s, 3H); ¹³C NMR (75 MHz, CD₂Cl₂): d=230.3 (C), 140.4 (C),

134.7 (CH), 134.5 (CH), 132.1 (CH), 131.8 (CH), 130.4 (CH), 129.1 (t,

J(C,P)=5.3 Hz, CH), 128.4 (C), 44.9 (CH₃); ³¹P NMR (121 MHz,

CD₂Cl₂): d=19.9, ꢀ143.9 (hept., J(P,F)=711 Hz); IR (KBr): n˜ =3058,

1616, 1586, 1574, 1532, 1481, 1435, 1404, 1391, 1322, 1308, 1267, 1225,

1191, 1133, 1095, 1071, 1027, 999, 924, 897, 877, 838, 745, 735, 694, 617,

557, 520, 495 cm^ꢀ1; MS (ESI-pos.): m/z: 830.2 [M ⁺ꢀPF₆], 570.1 [M ⁺

ꢀPF₆ꢀPPh₃]; elemental analysis calcd (%) for: C 55.34, H 4.23, N 1.43;

found: C 55.37, H 4.21, N 1.38.

Compound 33: yellow solid (151 mg, 43%); ¹H NMR (400 MHz,

CD₂Cl₂): d=7.50–7.46 (m, 4H), 7.40–7.36 (m, 3H), 7.27–7.23 (m, 6H),

7.20–7.11 (m, 17H), 6.84–6.81 (m, 2H), 6.62 (br, 2H), 5.79–5.74 (m, 1H),

4.15–4.11 (m, 1H), 3.90 (s, 3H), 2.03 (d, J=6.6 Hz, 3H), 1.59 (d, J=

6.7 Hz, 3H), 1.07 (d, J=6.9 Hz, 3H), 0.94 (d, J=7.0 Hz, 3H); ¹³C NMR

(75 MHz, CD₂Cl₂): d=235.1 (C), 161.4 (C), 135.9 (d, J(C,P)=3.0 Hz, C),

134.8 (d, J(C,P)=10.7 Hz, CH), 134.6 (d, J(C,P)=10.4 Hz, CH), 134.0 (d,

J(C,P)=12.1 Hz, C), 132.3 (d, J(C,P)=2.7 Hz, CH), 130.9 (d, J(C,P)=

2.4 Hz, CH), 130.3 (d, J(C,P)=50.2 Hz, C), 129.2 (d J(C,P)=11.2 Hz,

CH), 128.4 (d, J(C,P)=10.3 Hz, CH), 127.3 (CH), 113.2 (CH), 71.0

(CH₃), 57.0 (CH), 55.8 (CH), 25.2 (CH₃), 21.8 (CH₃), 21.1 (CH₃), 20.3

(CH₃); ³¹P NMR (121 MHz, CD₂Cl₂): d=29.0 (d, J=37.2 Hz), 22.7 (d,

J=37.3 Hz), ꢀ143.9 (hept., J(P,F)=711 Hz); IR (KBr): n˜ =3057, 2987,

2939, 2845, 1600, 1572, 1503, 1481, 1438, 1392, 1376, 1368, 1310, 1284,

1256, 1209, 1179, 1160, 1143, 1096, 1026, 997, 875, 839, 742, 693, 629, 594,

557, 530, 519, 507 cm^ꢀ1; MS (ESI-pos.): m/z: 884.2 [M ⁺ꢀPF₆], 622.1 [M ⁺

ꢀPF₆ꢀPPh₃], 586.1 [M ⁺ꢀPF₆ꢀPPh₃ꢀCl]; elemental analysis calcd (%)

for: C 58.26, H 4.99, N 1.36; found: C 58.33, H 5.08, N 1.32.

MS (ESI-pos.): m/z: 853.3 [M ⁺ꢀPF₆]; elemental analysis calcd (%) for:

C 57.79, H 4.45, N 2.81; found: C 57.86, H 4.37, N 2.72.

Representative procedure for the preparation of palladium carbene com-

plexes by oxidative insertion into amidinium chloride salts—Compound

13: A solution of the imidazolium salt 8a (X=Cl) (150 mg, 0.47 mmol)

and [Pd(PPh₃)₄] (543 mg, 0.47 mmol) in CH₂Cl₂(30 mL) was stirred

under argon for 16 h at ambient temperature. The solvent was removed

in vacuo, the waxy residue was suspended in pentane and stirred for 1 h

at ambient temperature to form a fine powder. The pentane was discard-

ed and the residue was extracted with pentane to remove the remaining

PPh₃. The crude product was then recrystallized from CH₂Cl₂to precipi-

tate impurities. After filtration, the crystallization of the product was in-

duced by slowly diffusing pentane into the CH₂Cl₂solution, affording

product 13 as

a

yellow solid (230 mg, 70%). ¹H NMR (400 MHz,

CD₂Cl₂): d=7.80–7.74 (m, 5H), 7.59–7.52 (m, 3H), 7.50–7.44 (m, 8H),

7.38–7.35 (m, 3H), 7.30–7.23 (m, 4H), 6.49–6.47 (m, 2H), 4.54 (d, J=

11.6 Hz, 1H), 4.01 (d, J=11.6 Hz, 1H), 3.20 (s, 3H), 3.00 (s, 3H);

¹³C NMR (100 MHz, CD₂Cl₂): d=195.0 (C), 136.4 (C), 135.5 (C), 134.7

(d, J(C,P)=11.4 Hz, CH), 131.5 (d, J(C,P)=2.4 Hz, CH), 131.0 (d,

J(C,P)=52.3 Hz, C), 130.7 (CH), 129.9 (CH), 129.4 (CH), 129.1 (CH),

128.8 (d, J(C,P)=11.0 Hz, CH), 128.1 (CH), 127.3 (CH), 78.3 (CH), 75.7

(CH), 36.5 (CH₃), 35.5 (CH₃); ³¹P NMR (162 MHz, CD₂Cl₂): d=27.90;

IR (KBr): n˜ =3050, 2963, 2909, 1702, 1650, 1586, 1571, 1525, 1492, 1481,

1455, 1436, 1407, 1393, 1262, 1194, 1158, 1096, 1027, 999, 942, 923, 803,

747, 721, 703, 693, 653, 619, 585, 533, 508 cm^ꢀ1; MS (ESI-pos., CH₂Cl₂):

m/z: 653.2 [M ⁺ꢀCl]; elemental analysis calcd (%) for: C 60.93, H 4.82,

N 4.06; found: C 61.05, H 4.76, N 4.03.

The following complexes were prepared analogously:

Compound 35: yellow solid (71 mg, 22%); ¹H NMR (400 MHz, CD₂Cl₂):

d=7.63–7.38 (m, 30H), 6.84–6.82 (m, 2H), 6.64–6.61 (m, 2H), 4.34 (t, J=

5.8 Hz, 2H), 3.81 (s, 3H), 2.91 (t, J=5.3 Hz, 2H), 1.63–1.62 (m, 2H),

1.55–1.51 (m, 4H); ¹³C NMR (75 MHz, CD₂Cl₂): d=226.5 (C), 162.9 (C),

140.4 (C), 135.9 (d, J(C,P)=3.0 Hz, C), 134.6 (t, J(C,P)=6.2 Hz, CH),

131.9 (CH), 131.1 (CH), 129.1 (t, J=5.3 Hz, CH), 114.1 (CH), 63.4

(CH₂), 56.6 (CH₂), 56.0 (CH₃), 26.0 (CH₂), 24.8 (CH₂), 22.9 (CH₂);

³¹P NMR (121 MHz, CD₂Cl₂): d=23.9, ꢀ143.9 (hept., J(P,F)=711 Hz);

IR (KBr): n˜ =3060, 2954, 2863, 2677, 2580, 1599, 1541, 1505, 1482, 1436,

1310, 1265, 1232, 1172, 1109, 1095, 1072, 1024, 999, 931, 839, 747, 725,

692, 645, 604, 558, 520, 494 cm^ꢀ1; MS (ESI-pos.): m/z: 868.2 [M ⁺ꢀPF₆],

608.2 [M ⁺ꢀPF₆ꢀPPh₃]; elemental analysis calcd (%) for: C 58.00, H

4.67, N 1.38; found: C 57.92, H 4.58, N 1.34.

Compound 9a (X=Cl): Colorless solid (458 mg, 67%). In solution, this

product exists as an equilibrium mixture of the cationic form 9a, the neu-

tral form and PPh₃(1:0.28:0.46). ¹H NMR (400 MHz, CD₂Cl₂): d=7.80–

7.51 (m, 3H), 7.70–7.66 (m, 4H), 7.62–7.51 (m, 10H), 7.47–7.05 (m,

52H), 4.99–4.93 (m, 1H), 3.74–3.44 (m, 5H), 3.39–3.29 (m, 2H), 3.15–

3.09 (m, 1H), 3.01–2.92 (m, 1H), 2.29–2.09 (m, 2H), 2.03–1.72 (m, 4H),

1.57–1.47 (m, 1H), 0.71–0.60 (m, 1H); ¹³C NMR (100 MHz, CD₂Cl₂): d=

193.2 (C), 193.1 (C), 139.8 (C), 139.2 (C), 137.5 (d, J(C,P)=21.1 Hz, C,

PPh₃), 134.5 (d, J(C,P)=11.5 Hz, CH), 134.3 (t, J(C,P)=6.1 Hz, CH),

133.8 (d, J(C,P)=19.7 Hz, PPh₃), 132.1 (CH), 132.0 (CH), 131.9 (CH),

131.1 (d, J(C,P)=2.4 Hz, CH), 130.1 (d, J(C,P)=54.5 Hz, C), 129.5 (s, C),

129.1 (t, J(C,P)=13.3 Hz, CH), 128.8 (CH, PPh₃), 128.6 (d, J(C,P)=

6.9 Hz, CH, PPh₃), 128.2 (d, J(C,P)=11.2 Hz, CH), 126.8 (CH), 126.3

(CH), 120.6 (CH), 118.9 (CH), 64.3 (CH), 63.1 (CH), 55.0 (CH₂), 54.3

(CH₂), 47.4 (CH₂), 46.4 (CH₂), 30.4 (CH₂), 30.0 (CH₂), 26.1 (CH₂), 24.4

(CH₂); ³¹P NMR (162 MHz, CD₂Cl₂): d=27.5 (neutral), 23.1 (cationic),

ꢀ4.3 (PPh₃); IR (KBr): n˜ =3051, 2961, 2927, 2876, 1597, 1585, 1514, 1495,

1481, 1467, 1434, 1409, 1371, 1320, 1286, 1257, 1158, 1118, 1093, 1027,

997, 804, 746, 721, 694, 624, 542, 517, 497, 470 cm^ꢀ1; MS (ESI-pos.): m/z:

851.2 (cationic form, [M ⁺ꢀCl]), 589.1 (neutral form, [M ⁺ꢀCl]); elemen-

tal analysis calcd (%) for the cationic complex: C 64.91, H 4.99, N 3.15;

found: C 64.72, H 5.15, N 3.08.

Compound 9b (X=PF₆)

Method A: A suspension of the imidazolium salt 6b (X=PF₆, 100 mg,

0.27 mmol) and [Pd(PPh₃)₄] (312 mg, 0.27 mmol, 1 equiv) in CH₂Cl₂

(18 mL) was refluxed under argon for 2 h. For work up, the solvent was

removed in vacuo, the waxy residue was suspended in pentane and stir-

red for 1 h at RT to form a fine powder. The pentane was discarded and

the residue was extracted with pentane to remove the remaining PPh₃.

The crude product was then recrystallized from CH₂Cl₂to precipitate im-

purities. After filtration, crystallization of the product was induced by

slowly diffusing pentane into the CH₂Cl₂solution affording the desired

product 9b as a pale yellow solid (110 mg, 41%).

Complex 11 (X=Cl): colorless foam (85%); ¹H NMR (400 MHz,

CD₂Cl₂): d=7.76–7.71 (m, 6H), 7.52–7.47 (m, 3H), 7.44–7.39 (m, 6H),

4.03 (dt, J=13.2, 4.7 Hz, 1H), 3.90 (dt, J=13.4, 4.4 Hz, 1H), 3.43 (dt, J=

13.1, 4.8 Hz), 3.01 (dt, J=13.1, 4.7 Hz, 1H), 2.95–2.88 (m, 1H), 2.01–1.93

(m, 2H), 1.92–1.83 (m, 2H), 1.82–1.69 (m, 3H), 1.37–0.98 (m, 6H), 0.93

(s, 9H), 0.92 (s, 9H); ¹³C NMR (100 MHz, CD₂Cl₂): d=194.5, 134.9

Method B: AgPF₆(35 mg, 0.14 mmol) was added to a solution of the cor-

responding chloride complex 9a (X=Cl, 125 mg, 0.14 mmol) in CH₂Cl₂

(1 mL) and the resulting suspension was stirred for 1 h under argon. The

mixture was filtered and the solvent was evaporated to give the desired

product as

a

pale yellow solid (99 mg, 71%). ¹H NMR (400 MHz,

2

1

(j J_{P, C}

+

⁴J_P,Cj=11.2 Hz), 131.3 (J=2.7 Hz), 130.9 (j J_{P, C}

+

³J_P,Cj=

CD₂Cl₂): d=7.71–7.66 (m, 5H), 7.60–7.50 (m, 13H), 7.44–7.34 (m, 12H),

7.26–7.17 (m, 5H), 3.67–3.57 (m, 1H), 3.44–3.30 (m, 2H), 3.06 (t, J=

10.7 Hz, 1H), 2.88–2.86 (m, 1H), 1.94–1.90 (m, 1H), 1.75–1.72 (m, 2H),

0.62 (t, J=9.7 Hz, 1H); ¹³C NMR (100 MHz, CD₂Cl₂): d=190.0 (C),

139.2 (C), 134.4 (t, J(C,P)=6.2 Hz, CH), 132.1 (CH), 131.9 (CH), 129.5

(C), 129.1 (dt, J(C,P)=13.0, 5.3 Hz, CH), 126.3 (CH), 118.7 (CH), 63.9

(CH), 54.7 (CH₂), 46.4 (CH₂), 29.8 (CH₂), 26.1 (CH₂); ³¹P NMR

(121 MHz, CD₂Cl₂): d=22.8, ꢀ143.4 (hept., J(P,F)=711 Hz); IR (KBr):

3

52.9 Hz), 128.5 (j J_{P, C}

+

⁵J_{P, C}j=11.0 Hz), 67.8, 67.2, 45.9, 45.3, 42.2, 39.9,

29.8, 29.7, 29.1, 28.9, 28.0, 24.0, 23.8; ³¹P NMR (162 Hz, CD₂Cl₂): d=27.5;

IR (KBr): n˜ =3054, 2952, 2865, 1587, 1573, 1483, 1450, 1436, 1394, 1365,

1354, 1325, 1307, 1251, 1236, 1191, 1162, 1095, 1064, 1028, 999, 967, 911,

842, 749, 695, 662, 641, 616, 533, 513, 494; MS (ESI-pos) m/z: 695.25 [M ⁺

ꢀCl]; elemental analysis calcd (%) for C 60.70, H 7.02, N 3.83; found: C

60.45, H 7.12, N 3.69.

Chem. Eur. J. 2005, 11, 1833 – 1853

www.chemeurj.org

ꢃ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

1847

A. Fꢂrstner et al.

Compound 16a (X=Cl): pale yellow solid (278 mg, 62%). In solution,

this product exists as an equilibrium mixture of the cationic form, the

neutral form, and PPh₃(neutral/cationic/PPh₃0.37:1:0.34). ¹H NMR

(400 MHz, CD₂Cl₂): d=7.80–7.68 (m, 15H), 7.59–7.47 (m, 24H), 7.45–

7.47 (m, 6H), 7.32–7.27 (m, 15H), 3.51 (s, 6H), 3.33 (s, 6H), 2.96–2.91

(m, 2H), 2.49 (ddd, J=12.7, 7.8, 4.8 Hz, 2H), 2.31 (t, J=6.0 Hz, 4H),

1.68–1.65 (m, 1H), 1.31–1.24 (m, 1H), 0.93 (quint., J=5.9 Hz, 2H);

¹³C NMR (100 MHz, CD₂Cl₂): d=187.4 (C), 186.0 (C), 137.2 (C, PPh₃),

134.5 (d, J(C,P)=11.4 Hz, CH), 134.4 (t, J(C,P)=6.4 Hz, CH), 133.7 (d,

J(C,P)=19.6 Hz, CH, PPh₃), 131.9 (CH), 131.3 (d, J(C,P)=2.6 Hz, CH),

130.6 (d, J(C,P)=52.4 Hz, C), 129.4 (d, J(C,P)=25.1 Hz, C), 129.1 (t,

J(C,P)=5.2 Hz, CH), 128.8 (CH, PPh₃), 128.51 (d, J(C,P)=6.3 Hz, CH,

PPh₃), 128.47 (d, J(C,P)=11.1 Hz, CH), 46.5 (CH₂), 46.2 (CH₃), 45.93

(CH₂), 45.90 (CH₃), 19.5 (CH₂), 18.1 (CH₂); ³¹P NMR (162 MHz,

CD₂Cl₂); d=26.5 (neutral), 22.2 (cationic), ꢀ4.6 (PPh₃); IR (KBr): n˜ =

3049, 2916, 2850, 1697, 1629, 1575, 1522, 1629, 1575, 1522, 1493, 1480,

1434, 1402, 1359, 1318, 1240, 1217, 1185, 1159, 1094, 1025, 998, 856, 748,

695, 619, 599, 521, 495 cm^ꢀ1; MS (ESI-pos., CH₂Cl₂): m/z: 777.2 (cationic

complex, [M ⁺ꢀCl]); elemental analysis calcd (%) for the cationic com-

plex: C 61.97, H 5.20, N 3.44; found C 62.10, H 5.12, N 3.38.

CH), 126.9 (CH), 112.7 (CH), 69.6 (CH₃), 55.8 (CH), 55.5 (CH), 20.8

(CH₃), 20.6 (CH₃); ³¹P NMR (162 MHz, CD₂Cl₂): d=26.1; IR (KBr): n˜ =

3053, 2973, 2934, 2875, 2836, 1601, 1563, 1502, 1481, 1454, 1435, 1390,

1373, 1308, 1291, 1253, 1220, 1177, 1163, 1142, 1096, 1072, 1026, 1000,

838, 782, 747, 730, 693, 629, 595, 530, 510, 496, 456 cm^ꢀ1; MS (ESI-pos.):

m/z: 624.1 [M ⁺ꢀCl], 586.1 [M ⁺ꢀ2 Cl], 218.2 [M ⁺ꢀ2ClꢀPPh₃ꢀPd]; ele-

mental analysis calcd (%) for: C 58.33, H 5.51, N 2.13; found: C 58.24, H

5.59, N 2.16.

Compound 34: pale yellow solid (116 mg, 50%); ¹H NMR (400 MHz,

CD₂Cl₂): d=7.50–7.26 (m, 15H), 6.71–6.70 (m, 4H), 5.52–5.45 (m, 1H),

4.06–3.99 (m, 1H), 3.81 (s, 3H), 3.10–3.04 (m, 1H), 2.54–2.48 (m, 1H),

1.92–1.85 (m, 2H), 1.68–1.50 (m, 4H); ¹³C NMR (100 MHz, CD₂Cl₂): d=

226.4 (d, J(C,P)=6.6 Hz, C), 161.1 (C), 134.6 (d, J(C,P)=11.4 Hz, CH),

133.7 (d, J=19.7 Hz, C), 131.1 (d, J(C,P)=2.7 Hz, CH), 130.5 (d,

J(C,P)=52.5 Hz, C), 129.0 (CH), 128.4 (d, J(C,P)=10.9 Hz, CH), 113.4

(CH), 63.7 (CH₂), 55.6 (CH₃), 55.1 (CH₂), 26.6 (CH₂), 25.7 (CH₂), 23.7

(CH₂); ³¹P NMR (162 MHz, CD₂Cl₂): d=26.0; IR (KBr): n˜ =3053, 2942,

2861, 2677, 1600, 1570, 1505, 1481, 1435, 1352, 1300, 1278, 1256, 1234,

1176, 1136, 1096, 1072, 1026, 999, 951, 858, 836, 804, 777, 746, 694, 606,

568, 532, 511, 498 cm^ꢀ1; MS (ESI-pos.): m/z: 868.2 [M ⁺ꢀCl], 608.1 [M ⁺

ꢀClꢀPPh₃]; elemental analysis calcd (%) for: C 57.92, H 5.02, N 2.18;

found: C 57.84, H 5.10, N 2.21.

Compound 22: colorless solid (124 mg, 40%). In solution, this product

exists as an equilibrium mixture of the cationic form, the neutral form,

and PPh₃(neutral/cationic/PPh₃0.64:1:0.86). ¹H NMR (400 MHz,

CD₂Cl₂): d=7.73–7.66 (m, 15H), 7.59–7.47 (m, 24H), 7.46–7.40 (m, 6H),

7.32–7.27 (m, 15H), 3.45 (s, 6H), 3.00 (s, 6H), 2.73 (s, 6H), 2.12 (s, 6H);

¹³C NMR (100 MHz, CD₂Cl₂): d=201.3 (C), 201.2 (C), 137.5 (d, J(C,P)=

20.1 Hz, C, PPh₃), 134.6 (d, J(C,P)=11.1 Hz, CH), 134.4 (t, J(C,P)=

6.3 Hz, CH), 133.7 (d, J(C,P)=19.6 Hz, CH, PPh₃), 131.9 (s, CH), 131.3

(d, J(C,P)=2.2 Hz, CH), 130.9 (d, J(C,P)=51.3 Hz, C), 129.6 (d, J(C,P)=

25.6 Hz, C), 129.3 (t, J(C,P)=5.3 Hz, CH), 128.8 (CH, PPh₃), 128.6 (d,

J(C,P)=11.2 Hz, CH), 128.5 (CH, PPh₃), 47.1 (CH₃), 43.3 (CH₃);

³¹P NMR (162 MHz, CD₂Cl₂): d=27.5 (neutral), 22.8 (cationic), ꢀ4.6

(PPh₃); IR (KBr): n=3050, 2955, 2916, 2849, 2674, 1617, 1563, 1480,

1434, 1404, 1382, 1309, 1265, 1185, 1158, 1094, 1052, 1026, 997, 917, 868,

747, 694, 612, 521, 495 cm^ꢀ1; MS (ESI-pos.): m/z: 505.0 (neutral complex,

[M ⁺ꢀCl]), 767.2 (cationic complex, [M ⁺ꢀCl]; elemental analysis calcd

(%) for the neutral complex: C 51.18, H 5.04, N 5.19; found: C 51.08, H

5.11, N 5.08.

Compound 27a (X=O): clorless solid (190 mg, 35%); ¹H NMR

(400 MHz, CD₂Cl₂): d = 7.50–7.46 (m, 3H), 7.40–7.20 (m, 17H), 3.80 (s,

3H), 3.01 (s, 3H); ¹³C NMR (75 MHz, CD₂Cl₂): d=204.8 (d, J=6.2 Hz,

C), 154.1 (C), 134.3 (d, J(C,P)=11.2 Hz, CH), 131.4 (d, J(C,P)=2.7 Hz,

CH), 129.6 (CH), 128.5 (d, J(C,P)=11.2 Hz, CH), 126.9 (C), 122.2 (CH),

115.7 (CH), 44.7 (CH₃), 38.7 (CH₃); ³¹P NMR (162 MHz, CD₂Cl₂): d=

26.17; IR (KBr): n˜ =3052, 2984, 2923, 1622, 1599, 1577, 1483, 1455, 1435,

1412, 1355, 1310, 1275, 1246, 1187, 1147, 1096, 1071, 1026, 999, 820, 759,

693, 609, 534, 510, 498 cm^ꢀ1; MS (ESI-pos.): m/z: 552.1 [M ⁺ꢀCl]; ele-

mental analysis calcd (%) for: C 55.08, H 4.45, N 2.38, found: C 54.95, H

4.49, N 2.43.

Representative procedure for the formation of nickel complexes by oxi-

dative addition—Compound 37: [Ni(cod)₂] (99 mg, 0.36 mmol) was added

to a solution of PPh₃(189 mg, 0.72 mmol) in anhydrous THF (10 mL)

and the dark red mixture was stirred for 15 min under argon. The imida-

zolium salt 1a (100 mg, 0.36 mmol) was then introduced and the resulting

brown-yellow suspension was stirred for 3 h at ambient temperature caus-

ing the precipitation of a yellow solid. This precipitate was allowed to

settle, the supernatant solution was siphoned off, and the solid was dried

in vacuo to give product 37 as a yellow solid (267 mg, 86%). Crystals

suitable for X-ray structure analysis were formed by slowly diffusing pen-

tane into

a

CH₂Cl₂solution of the complex. ¹H NMR (400 MHz,

CD₂Cl₂): d=7.75–7.71 (m, 12H), 7.61–7.50 (m, 18H), 3.13 (s, 6H), 2.49

(s, 4H); ¹³C NMR (100 MHz, CD₂Cl₂): d=197.1 (C), 134.3 (t, J(C,P)=

5.6 Hz, CH), 131.9 (CH), 129.1 (d, J(C,P)=48.2 Hz, C), 129.0 (d,

J(C,P)=5.5 Hz, CH), 51.0 (CH₂), 36.8 (CH₃); ³¹P NMR (121 MHz,

CD₂Cl₂): d=21.6, ꢀ143.9 (hept., J(P,F)=710.6 Hz); IR (KBr): n˜ =3057,

2957, 2924, 2884, 1646, 1587, 1572, 1543, 1516, 1482, 1435, 1402, 1323,

1287, 1208, 1190, 1095, 1028, 999, 838, 745, 695, 620, 558, 524, 513,

494 cm^ꢀ1; MS (ESI-pos.): m/z: 453.0 [M ⁺ꢀPF₆ꢀPPh₃]; elemental analysis

calcd (%) for: 57.14, H 4.68, N 3.25; found: C 56.98, H 4.78, N 3.21.

The following complexes were analogously prepared:

Complex 38: yellow solid (223 mg, 62%); ¹H NMR (400 MHz, CD₂Cl₂):

d=7.73–7.72 (m, 12H), 7.59–7.52 (m, 18H), 3.13 (s, 6H), 2.50 (s, 4H);

¹³C NMR (100 MHz, CD₂Cl₂): d=197.0 (C), 134.3 (t, J(C,P)=5.1 Hz,

CH), 131.9 (CH), 129.1 (d, J(C,P)=48.3 Hz, C), 129.0 (J(C,P)=5.1 Hz,

CH), 51.0 (CH₂), 36.8 (CH₃); ³¹P NMR (162 MHz, CD₂Cl₂): d=21.8; IR

(KBr): n˜ =3053, 2951, 2869, 2678, 1670, 1585, 1571, 1543, 1517, 1481,

1436, 1400, 1323, 1287, 1207, 1184, 1163, 1092, 1055, 998, 901, 805, 751,

698, 621, 522, 494 cm^ꢀ1; MS (ESI-pos.): m/z: 715.2 [M ⁺ꢀBF₄], 453.1 [M ⁺

ꢀBF₄ꢀPPh₃]; elemental analysis calcd (%) for: C 61.27, H 5.02, N 3.49;

found: C 61.20, H 5.12, N 3.41.

Complex 39: yellow solid (160 mg, 77%); ¹H NMR (400 MHz, CD₂Cl₂):

d=3.66 (t, J=1.3 Hz, 4H), 3.52 (s, 6H), 1.70–1.62 (m, 12H), 1.21 (quint.,

J=7.9 Hz, 18H); ¹³C NMR (100 MHz, CD₂Cl₂): d=198.3 (J(C,P)=

31.3 Hz, C), 51.6 (CH₂), 37.4 (CH₃), 15.0 (J(C,P)=13.9 Hz, CH₃), 8.4

(CH₂); ³¹P NMR (121 MHz, CD₂Cl₂): d=17.4, ꢀ143.9 (hept., J(P,F)=

710.6 Hz); IR (KBr): n=2971, 2942, 2882, 2801, 1537, 1517, 1483, 1458,

1435, 1407, 1380, 1325, 1292, 1260, 1210, 1101, 1038, 1014, 929, 876, 839,

756, 739, 725, 701, 631, 557 cm^ꢀ1; MS (ESI-pos.): m/z: 427.2 [M⁺-PF₆],

309.1 [M⁺-PF₆-PEt₃]; elemental analysis calcd (%) for: C 35.60, H 7.03,

N 4.88; found: C 35.84, H 6.89, N 4.81.

Compound 27b (X=S): colorless solid (166 mg, 64%); ¹H NMR

(400 MHz, CD₂Cl₂): d=7.95–7.93 (m, 2H), 7.65–7.60 (m, 3H), 7.49–7.43

(m, 7H), 7.35–7.27 (m, 19H), 3.94 (s, 3H), 3.05 (s, 3H); ¹³C NMR

(75 MHz, CD₂Cl₂): d=228.7 (C), 136.0 (CH), 134.5 (C), 132.1 (CH),

131.3 (d, J(C,P)=2.6 Hz, CH), 130.8 (CH), 129.7 (CH), 129.2 (CH), 128.4

(d, J(C,P)=11.1 Hz, CH), 44.7 (CH₃); ³¹P NMR (162 MHz, CD₂Cl₂): d=

25.9; IR (KBr): n˜ =3142, 3052, 2962, 2919, 2854, 2673, 1667, 1585, 1572,

1545, 1480, 1435, 1403, 1310, 1263, 1228, 1186, 1157, 1117, 1094, 1070,

1026, 998, 923, 900, 857, 803, 746, 721, 693, 617, 557, 533, 512, 495 cm^ꢀ1

;

MS (ESI-pos.): m/z: 832.1 [M ⁺ꢀCl], 570.0 [M ⁺ꢀClꢀPPh₃]; elemental

analysis calcd (%) for: C 62.33, H 4.77, N 1.62; found: C 62.26, H 4.83, N

1.65.

Complex 32: yellow solid (124 mg, 56%); ¹H NMR (400 MHz, CD₂Cl₂):

d=7.50–7.34 (m, 15H), 6.67–6.58 (m, 4H), 6.16 (hept., J=6.6 Hz, 1H),

4.07 (hept., J=7.0 Hz, 1H), 3.81 (s, 3H), 1.86 (d, J=6.6 Hz, 3H), 1.44 (d,

J=6.8 Hz, 3H), 1.05 (d, J=7.0 Hz, 3H), 0.90 (d, J=7.0 Hz, 3H);

¹³C NMR (75 MHz, CD₂Cl₂): d=232.4 (d, J=8.2 Hz, C), 160.4 (C), 134.8

(d, J(C,P)=11.2 Hz, CH), 133.9 (d, J=2.9 Hz, C), 131.04 (d, J(C,P)=

52.5 Hz, C), 131.03 (d, J(C,P)=2.5 Hz, CH), 128.4 (d, J(C,P)=10.9 Hz,

Compound 40: yellow solid (193 mg, 41%); ¹H NMR (400 MHz,

CD₂Cl₂): d=7.68–7.32 (m, 30H), 4.82 (m, 3H), 3.57 (m, 2H), 2.10 (m,

3H), 1.53–1.16 (m, 12H); ¹³C NMR (75 MHz, CD₂Cl₂): d=196.2 (C),

134.4 (CH), 131.7 (CH), 129.1 (t, J(C,P)=4.8 Hz, CH), 128.6 (C), 57.0

(CH₂), 25.2 (CH₂), 23.3 (CH₂); ³¹P NMR (121 MHz, CD₂Cl₂): d=21.8,

1848

ꢃ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

Chem. Eur. J. 2005, 11, 1833 – 1853

Carbene Complexes

FULL PAPER

ꢀ143.8 (hept., J(P,F)=711 Hz); IR (KBr): n˜ =3057, 2944, 2860, 1639,

1585, 1535, 1481, 1436, 1409, 1346, 1322, 1283, 1260, 1244, 1187, 1162,

1129, 1093, 1068, 1023, 999, 877, 839, 793, 748, 701, 610, 557, 520,

496 cm^ꢀ1; MS (ESI-pos.): m/z: 535.2 [M ⁺ꢀPF₆ꢀPPh₃]; elemental analysis

calcd (%) for: C 59.80, H 5.34, N 2.97; found: C 59.88, H 5.26, N 3.06.

Compound 41: yellow solid (135 mg, 50%); ¹H NMR (400 MHz,

CD₂Cl₂): d=7.69–7.50 (m, 30H), 4.47 (m, 4H), 2.76 (m, 4H), 1.43–1.35

(m, 8H); ¹³C NMR (100 MHz, CD₂Cl₂): d=191.5 (C), 134.4 (CH), 131.8

(CH), 129.5 (C), 129.1 (t, J(C,P)=4.9 Hz, CH), 56.8 (CH₂), 51.4 (CH₂),

25.7 (CH₂), 24.0 (CH₂); ³¹P NMR (121 MHz, CD₂Cl₂): d=18.6, ꢀ143.9

(hept., J(P,F)=711 Hz); IR (KBr): n˜ =3058, 2975, 2949, 2876, 1684, 1586,

1573, 1521, 1482, 1436, 1374, 1321, 1295, 1267, 1232, 1187, 1161, 1092,

1073, 1028, 999, 920, 839, 747, 698, 617, 558, 518, 494 cm^ꢀ1; MS (ESI-

pos.): m/z: 769.1 [M ⁺ꢀPF₆], 507.2 [M ⁺ꢀPF₆ꢀPPh₃]; elemental analysis

calcd (%) for: C 59.01, H 5.06, N 3.06; found: C 58.96, H 5.07, N 3.11.

aryl halide the mixture was adsorbed onto silica gel and purified by flash

chromatography.

1

Compound 52: H NMR (400 MHz, CDCl₃): d=8.21–8.19 (m, 1H), 7.51–

7.47 (m, 1H), 6.67–6.62 (m, 2H), 3.82 (t, J=4.8 Hz, 4H), 3.49 (t, J =

4.8 Hz, 4H); ¹³C NMR (100 MHz, CDCl₃): d=159.9 (C), 148.2 (CH),

137.9 (CH), 114.1 (CH), 107.3 (CH), 67.1 (CH₂), 46.0 (CH₂); IR (KAP):

n˜ =3051, 3004, 2962, 2892, 2852, 2689, 1725, 1593, 1565, 1481, 1436, 1376,

1333, 1312, 1242, 1216, 1160, 1121, 1070, 1056, 981, 943, 857, 775, 733,

645, 620, 532, 456 cm^ꢀ1; MS (EI): m/z (%): 164 (69) [M ⁺], 163 (42), 134

(13), 133 (67), 119 (25), 107 (47), 106 (16), 86 (10), 80 (10), 79 (100), 78

(30), 67 (10), 52 (11), 51 (15); HRMS: calcd for C₉H₁₂N₂O: 164.0950,

found: 164.0950.

Crystallographic data

Complex trans-2a: Empirical formula C₄₂H₄₁Cl₄F₆N₂P₃Pd, colorless, M_r=

1028.88, crystal size=0.20ꢅ0.17ꢅ0.16 mm, monoclinic, space group

P2₁/c, a=11.98900(10), b=23.8189(2), c=15.80730(10) ꢄ, b=102.858,

V=4400.96(6) ꢄ³, Z=4, 1_calcd=1.553 Mgm^ꢀ3, m=0.832 mm^ꢀ1, q range for

data collection=2.12 to 32.568, 110920 reflections, 15970 independent re-

flections, 14349 observed reflections [I>2s(I)], 523 parameters, S=

1.291, R₁=0.0374 (observed data), wR²=0.1586 (all data), largest diff.

peak/hole=1.061/ꢀ3.049 eꢄ^ꢀ3; CCDC-249509.

Thiourea 5: Empirical formula C₁₂H₁₄N₂S, colorless, M_r=218.31, crystal

size=0.18ꢅ0.13ꢅ0.10 mm, monoclinic, space group P2₁, a=5.30140(10),

b=12.9538(3), c=8.2297(2) ꢄ, b=107.7120(10)8, V=538.37(2) ꢄ³, Z=2,

1_calcd=1.347 Mgm^ꢀ3, m=0.267 mm^ꢀ1, q range for data collection=2.60 to

30.978, 14969 reflections, 3421 independent, 3224 observed reflections

[I>2s(I)], 192 parameters, S=1.036, R₁=0.0286 (observed data), wR²=

0.0717 (all data), largest diff. peak/hole=0.261/ꢀ0.157 eꢄ³; CCDC-

249510.

Compound 42: yellow solid (203 mg, 64%); ¹H NMR (400 MHz,

CD₂Cl₂): d=7.73–7.51 (m, 30H), 4.02 (s, 6H), 1.96 (m, 6H); ¹³C NMR

(100 MHz, CD₂Cl₂): d=199.9 (C), 134.3 (CH), 131.8 (CH), 129.6 (C),

129.2 (t, J(C,P)=4.9 Hz, CH), 47.7 (CH₃), 42.0 (CH₃). ³¹P NMR

(121 MHz, CD₂Cl₂): d=19.9, ꢀ143.9 (hept., J(P,F)=710.6 Hz); IR (KBr):

n˜ =3058, 2965, 2869, 1556, 1481, 1470, 1436, 1406, 1388, 1380, 1315, 1270,

1188, 1154, 1093, 1064, 1028, 1000, 837, 747, 697, 619, 558, 522, 493 cm^ꢀ1

;

MS (ESI-pos.): m/z: 717.1 [M ⁺ꢀPF₆], 455.1 [M ⁺ꢀPF₆ꢀPPh₃]; elemental

analysis calcd (%) for: C 57.01, H 4.90, N 3.24; found: C 57.11, H 5.01, N

3.21.

Representative procedure for the Heck reaction: A mixture of the aryl

halide (1.5 mmol, 1 equiv), butyl acrylate (1.65 mmol, 1.1 equiv), the Pd

complex (1 mol%) and Cs₂CO₃(3 mmol, 2 equiv) in NMP (1 mL) was

stirred for 16 h at 1208C under argon. After cooling, the mixture was di-

luted with water, the aqueous phase was repeatedly extracted with

CH₂Cl₂, the combined organic layers were dried (Na₂SO₄), the solvent

was evaporated and the residue was purified by flash chromatography to

give butyl cinnamate, the analytical and spectroscopic data of which were

identical to those of an authentic sample.

Complex 9a: Empirical formula C₄₉H₄₆Cl₄N₂P₂Pd, colorless, M_r=973.02,

crystal size=0.15ꢅ0.10ꢅ0.06 mm, orthorhombic, space group P2₁2₁2₁,

a=14.99730(10), b=15.29630(10), c=19.02290(10) ꢄ, V=4363.91(5) ꢄ³,

Z=4, 1_calcd=1.481 Mgm^ꢀ3, m=0.781 mm^ꢀ1, q range for data collection=

2.92 to 31.508, 63808 reflections, 14486 independent reflections, 12438

observed reflections [I>2s(I)], empirical absorption correction (multi-

scan method), 523 parameters, S=1.012, R₁=0.0366 (observed data),

wR²=0.0769 (all data), absolute structure parameter=ꢀ0.016(16), largest

diff. peak/hole=1.375/ꢀ0.785 eꢄ^ꢀ3; CCDC-249514.

Complex 9b: Empirical formula C₄₉H₄₆Cl₃F₆N₂P₃Pd, colorless, M_r=

1082.54, crystal size=0.28ꢅ0.20ꢅ0.05 mm, orthorhombic, space group

P2₁2₁2₁, a=14.80630(10), b=16.43080(10), c=19.2805(2) ꢄ, V=

4690.55(6) ꢄ³, Z=4, 1_calcd=1.533 Mgm^ꢀ3, m=0.730 mm^ꢀ1, q range for

data collection=4.11 to 31.078, 70574 reflections, 14999 independent re-

flections, 14084 observed reflections [I>2s(I)], Gaussian absorption cor-

rection (T_min/max=0.82/0.96), 577 parameter, S=1.015, R₁=0.0295 (ob-

served data), wR²=0.0683 (all data), absolute structure parameter=

ꢀ0.016(11), largest diff. peak/hole=0.468/ꢀ0.413 eꢄ^ꢀ3; CCDC-249513.

Representative procedure for the Suzuki reaction: A mixture of phenyl-

boronic acid (1.1 mmol, 1 equiv), 4-haloacetophenone (0.9 mmol,

1 equiv), the Pd-complex (1 mol%) and K₂CO₃(2.5 mmol, 2.8 equiv) in

THF (15 mL) was refluxed for 16 h under argon. After cooling, the mix-

ture was diluted with water, the aqueous phase was repeatedly extracted

with ethyl acetate, the combined organic layers were dried (Na₂SO₄), the

solvent was evaporated and the residue was purified by flash chromatog-

raphy (hexane/ethyl acetate 30:1) to give 4-phenyl-acetophenone, the an-

alytical and spectroscopic data of which were identical to those of an au-

thentic sample.^[58]

Representative procedure for the Kumada reaction: A suspension of the

aryl halide (0.5 mmol, 1 equiv) and the nickel complex (3 mol%) in THF

(0.5 mL) was stirred for 5 min at ambient temperature. After dropwise

addition of Grignard reagent (0.75 mmol, 1.5 equiv) the reaction mixture

was stirred for 18 h at RT under argon. The reaction was quenched with

MeOH, the mixture was diluted with water, the aqueous phase was re-

peatedly extracted with ethyl acetate, the combined organic layers were

dried (Na₂SO₄), the solvent was evaporated and the residue was purified

by flash chromatography.

2-(4-Methoxyphenyl)-pyridine (48): ¹H NMR (400 MHz, CDCl₃): d=

8.66–8.64 (m, 1H), 7.96–7.93 (m, 2H), 7.72–7.64 (m, 2H), 7.18–7.15 (m,

1H), 7.01–6.98 (m, 2H), 3.85 (s, 3H); ¹³C NMR (100 MHz, CDCl₃): d=

160.8 (C), 157.4 (C), 149.7 (CH), 137.1 (CH), 132.2 (C), 128.5 (CH),

121.7 (CH), 120.2 (CH), 116.5 (CH), 115.0 (CH), 114.5 (CH), 55.6 (CH₃);

IR (KBr): n˜ =3051, 2998, 2960, 2937, 2836, 1608, 1588, 1563, 1515, 1465,

1435, 1307, 1272, 1248, 1178, 1152, 1112, 1037, 1023, 988, 839, 806, 780,

737, 718, 638, 580, 556, 487 cm^ꢀ1; MS (EI): m/z (%): 185 (100) [M ⁺], 170

(29), 154 (4), 142 (36), 141 (18), 127 (2), 115 (7), 89 (5), 78 (3), 63 (5), 51

(4), 39 (3); HRMS: calcd for C₁₂H₁₁NO: 185.0841, found: 185.0840.

Complex 11: Empirical formula C₃₇H₅₁Cl₂N₂PPd, colorless, M_r=732.07,

crystal size=0.15ꢅ0.12ꢅ0.05 mm, orthorhombic, space group P2₁2₁2₁,

a=10.92080(10), b=14.09380(10), c=24.0674(3) ꢄ, V=3704.35(6) ꢄ³,

Z=4, 1_calcd=1.313 Mgm^ꢀ3, m=0.715 mm^ꢀ1, q range for data collection=

2.92 to 30.998, 50077 reflections, 11796 independent reflections, 10146

observed reflections [I>2s(I)], Gaussian absorption correction (T_min/

_max=0.91/0.96), 388 parameters, S=0.847, R₁=0.0406 (observed data),

wR²=0.1200 (all data), largest diff. peak/hole=0.554/ꢀ0.471 eꢄ^ꢀ3

;

CCDC-249517.

Complex 12: Empirical formula C₅₃H₄₈ClF₆N₂P₃Pdꢅ2CH₂Cl₂, colorless,

¯

M_r=1231.55, crystal size=0.20ꢅ0.13ꢅ0.06 mm, triclinic, space group P1,

a=11.78560(10), b=12.0961(2), c=12.2016(2) ꢄ, a=92.1710(10), b=

116.9250(10), g=114.2700(10)8, V=1359.07(3) ꢄ³, Z=1, 1_calcd

=

1.505 Mgm^ꢀ3, m=0.735 mm^ꢀ1, q range for data collection=3.09 to 33.218,

34742 reflections, 18690 independent reflections, 16740 observed reflec-

tions [I>2s(I)], empirical absorption correction (multiscan method), 649

parameters, S=0.929, R₁=0.0492 (observed data), wR²=0.1474 (all

data), absolute structure parameter=ꢀ0.014(18), largest diff. peak/hole=

1.257/ꢀ1.079 eꢄ^ꢀ3; CCDC-249523.

Representative procedure for the Hartwig–Buchwald reaction: A mixture

of the aryl halide (1 mmol, 1 equiv), morpholine (1.2 mmol, 1.2 equiv),

the Pd complex (1 mol%) and NaOtBu (2 mmol, 2 equiv) in DME

(1 mL) was stirred for 5 h at ambient temperature or 708C under argon.

The reaction was monitored by GC and after complete consumption of

Chem. Eur. J. 2005, 11, 1833 – 1853

www.chemeurj.org

ꢃ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

1849

A. Fꢂrstner et al.

Complex 13: Empirical formula C₃₅H₃₃Cl₂N₂PPd, pale yellow, M_r=

689.90, crystal size=0.08ꢅ0.08ꢅ0.06 mm, orthorhombic, space group

5575 independent reflections, 4803 observed reflections [I>2s(I)], 348

parameters, S=1.066, R₁=0.0433 (observed data), wR²=0.1285 (all

data), largest diff. peak/hole=1.607/ꢀ0.998 eꢄ^ꢀ3; CCDC-249530.

P2₁2₁2₁,

a=10.58720(10),

b=16.3433(2),

c=18.2229(2) ꢄ,

V=

3153.10(6) ꢄ³, Z=4, 1_calcd=1.453 Mgm^ꢀ3, m=0.836 mm^ꢀ1, q range for

data collection=2.95 to 33.158, 58136 reflections, 11978 independent re-

flections, 9814 observed reflections [I>2s(I)], Gaussian absorption cor-

rection (T_min/max=0.94/0.96), 372 parameters, S=1.001, R₁=0.0404 (ob-

served data), wR²=0.0726 (all data), absolute structure parameter=

ꢀ0.021(17), largest diff. peak/hole=0.462/ꢀ0.592 eꢄ^ꢀ3; CCDC-249512.

Complex 28b: Empirical formula C₄₆H₄₃Cl₃F₆NP₃PdS, colorless, M_r=

1061.53, crystal size=0.06ꢅ0.04ꢅ0.04 mm, monoclinic, space group

P2₁/c, a=19.2454(4), b=13.9966(3), c=17.0816(2) ꢄ, b=97.2090(10)8,

V=4564.90(15) ꢄ³, Z=4, 1_calcd=1.545 Mgm^ꢀ3, m=0.792 mm^ꢀ1, q range

for data collection=2.91 to 30.988, 77600 reflections, 14509 independent

reflections, 10033 observed reflections [I>2s(I)], Gaussian absorption

correction (T_min/max=0.96/0.98), 552 parameters, S=1.000, R₁=0.0491

(observed data), wR²=0.1053 (all data), largest diff. peak/hole=1.338/

ꢀ1.368 eꢄ^ꢀ3; CCDC-249531.

Complex 16a: Empirical formula C₄₃H₄₈Cl₄N₂O₂P₂Pd, colorless, M_r=

934.97, crystal size=0.22ꢅ0.16ꢅ0.12 mm, hexagonal, space group P6₃/m,

a=22.24080(10), b=22.24080(10), c=14.698 ꢄ, V=6296.45(4) ꢄ³, Z=6,

1_calcd=1.479 Mgm^ꢀ3, m=0.812 mm^ꢀ1, q range for data collection=4.21 to

32.038, 130892 reflections, 7538 independent reflections, 6382 observed

reflections [I>2s(I)], empirical absorption correction (multiscan

method), 278 parameters, S=1.099, R₁=0.0318 (observed data)=wR²=

0.0886 (all data), largest diff. peak/hole=1.623/ꢀ1.092 eꢄ^ꢀ3; CCDC-

249520.

Complex 32: Empirical formula C₃₂H₃₆Cl₂NOPPd, pale yellow, M_r=

658.89, crystal size=0.24ꢅ0.24ꢅ0.08 mm, monoclinic, space group P2₁/n,

a=10.49190(10), b=17.3034(2), c=16.0856(2) ꢄ, b=94.228, V=

2912.36(6) ꢄ³, Z=4, 1_calcd=1.503 Mgm^ꢀ3, m=0.902 mm^ꢀ1, q range for

data collection=3.06 to 30.998, 49601 reflections, 9247 independent re-

flections, 8441 observed reflections [I>2s(I)], gaussian absorption cor-

rection (T_min/max=0.88/0.95), 487 parameters, S=1.006, R₁=0.0234 (ob-

served data), wR²=0.0585 (all data), largest diff. peak/hole=0.459/

ꢀ0.599 eꢄ^ꢀ3; CCDC-249526.

Complex 16b: Empirical formula C₄₃H₄₄Cl₃F₆N₂P₃Pd, pale yellow, M_r=

1008.46, crystal size=0.46ꢅ0.14ꢅ0.14 mm, monoclinic, space group

P2₁/m, a=9.57680(10), b=22.7126(2), c=19.9983(2) ꢄ, b=93.628, V=

4341.22(7) ꢄ³, Z=4, 1_calcd=1.543 Mgm^ꢀ3, m=0.783 mm^ꢀ1, q range for

data collection=3.73 to 30.538, 61540 reflections, 13550 independent re-

flections, 12027 observed reflections [I>2s(I)], empirical absorption cor-

rection (multiscan method), 649 parameters, S=1.144, R₁=0.0471 (ob-

served data), wR²=0.1144 (all data), largest diff. peak/hole=1.344/

ꢀ1.041 eꢄ^ꢀ3; CCDC-249521.

Complex 33: Empirical formula C₅₁H₅₃Cl₃F₆NOP₃Pd, yellow, M_r=

¯

1115.60, crystal size=0.25ꢅ0.19ꢅ0.07 mm, triclinic, space group P1, a=

10.95160(10),

87.9010(10),

b=14.63970(10),

=

c=16.5360(2) ꢄ,

a=84.09,

b=

g

71.4710(10)8, V=2500.36(4) ꢄ³, Z=2, 1_calcd

=

1.482 Mgm^ꢀ3, m=0.688 mm^ꢀ1, q range for data collection=2.95 to 30.998,

60449 reflections, 15859 independent reflections, 14246 observed reflec-

tions [I>2s(I)], gaussian absorption correction (T_min/max=0.84/0.96), 597

parameters, S=1.060, R₁=0.0558 (observed data), wR²=0.1616 (all

data), largest diff. peak/hole=1.120/ꢀ2.750 eꢄ^ꢀ3; CCDC-249528.

Complex 19: Empirical formula C₄₈H₅₂ClF₆N₂P₃Pd₃, colorless, M_r=

1218.48, crystal size=0.25ꢅ0.10ꢅ0.05 mm, monoclinic, space group

P2₁/n, a=16.00390(10), b=11.25450(10), c=26.6487(2) ꢄ, b=92.968, V=

4793.43(6) ꢄ³, Z=4, 1_calcd=1.688 Mgm^ꢀ3, m=1.329 mm^ꢀ1, q range for

data collection=4.16 to 30.578, 98616 reflections, 14635 independent re-

flections, 12245 observed reflections [I>2s(I)], empirical absorption cor-

rection (multiscan method), 565 parameters, S=1.085, R₁=0.0633 (ob-

served data), wR²=0.1612 (all data), largest diff. peak/hole=2.535/

ꢀ1.599 eꢄ^ꢀ3; CCDC-249515.

Complex 34: Empirical formula

C_31.50H₃₂Cl_3.25NOPPd, colorless, M_r=

693.16, crystal size=0.08ꢅ0.05ꢅ0.04 mm, orthorhombic, space group

Pbcn, a=21.6007(2), b=16.6871(2), c=16.9748(2) ꢄ, V=6118.62(12) ꢄ³,

Z=8, 1_calcd=1.505 Mgm^ꢀ3,m=0.969 mm^ꢀ1, q range for data collection=

3.05 to 31.508, 90112 reflections, 10168 independent reflections, 8229 ob-

served reflections [I>2s(I)], 389 parameters, S=1.032, R₁=0.0384 (ob-

served data), wR²=0.1406 (all data), largest diff. peak/hole=1.059/

ꢀ1.217 eꢄ^ꢀ3; CCDC-249529.

Complex 22: Empirical formula C₂₄H₂₉Cl₄N₂PPd, colorless, M_r=624.66,

¯

crystal size=0.20ꢅ0.17ꢅ0.10 mm, triclinic, space group P1, a=

10.83190(10), b=10.86860(10), c=11.44660(10 ꢄ, a=100.76, b=91.15,

Nickelate complex 36: Empirical formula C₁₀H₂₀Cl₆N₄Ni, blue, M_r=

467.71, crystal size=0.16ꢅ0.15ꢅ0.14 mm, monoclinic, space group P2₁/c,

a=14.9304(2), b=8.85360(10), c=14.9304(2) ꢄ, b=103.678, V=

1917.69(4) ꢄ³, Z=4, 1_calcd=1.620 Mgm^ꢀ3, m=1.845 mm^ꢀ1, q range for

data collection=6.60 to 32.948, 26795 reflections, 6688 independent re-

flections, 5216 observed reflections [I>2s(I)], Gaussian absorption cor-

rection (T_min/max=0.84/0.94), 194 parameters, S=1.116, R₁=0.0355 (ob-

served data), wR²=0.0660 (all data), largest diff. peak/hole=0.523/

ꢀ0.442 eꢄ^ꢀ3; CCDC-249516.

g=90.988, V=1323.30(2) ꢄ³, Z=2, 1_calcd=1.568 Mgm^ꢀ3, m=1.181 mm^ꢀ1

,

q range for data collection=4.12 to 33.178, 42141 reflections, 10085 inde-

pendent reflections, 9236 observed reflections [I>2s(I)], empirical ab-

sorption correction (multiscan method), 293 parameters, S=0.994, R₁=

0.0258 (observed data), wR²=0.0740 (all data), largest diff. peak/hole=

1.693/ꢀ1.450 eꢄ^ꢀ3; CCDC-249519.

Complex 23: Empirical formula C₄₁H₄₂ClN₂P₃F₆Pd·2CH₂Cl₂, colorless,

M_r=1081.38, crystal size=0.19ꢅ0.17ꢅ0.02 mm, monoclinic, space group

P2₁/c, a=11.5234(2), b=27.8267(6), c=15.3671(3) ꢄ, b=110.2350(10)8,

V=4623.46(16) ꢄ³, Z=4, 1_calcd=1.554 Mgm^ꢀ3, m=0.852 mm^ꢀ1, q range

for data collection=4.12 to 30.458, 15643 reflections, 11335 independent

reflections, 7624 observed reflections [I>2s(I)], empirical absorption

correction (multiscan method), 541 parameters, S=1.084, R₁=0.0726

(observed data), wR²=0.1571 (all data), largest diff. peak/hole=1.404/

ꢀ1.002 eꢄ^ꢀ3; CCDC-249518.

Complex 37: Empirical formula C₄₂H₄₂Cl₃F₆N₂NiP₃, yellow, M_r=946.75,

¯

crystal size=0.20ꢅ0.19ꢅ0.05 mm, triclinic, space group P1, a=

12.58330(10), b=18.08800(10), c=20.55670(10) ꢄ, a=108.14, b=96.15,

g=100.608, V=4302.09(5) ꢄ³, Z=4, 1_calcd=1.462 Mgm^ꢀ3, m=0.808 mm^ꢀ1

,

q range for data collection=4.10 to 33.118, 135076 reflections, 32612 in-

dependent reflections, 26339 observed reflections [I>2s(I)], Gaussian

absorption correction (T_min/max=0.86/0.96), 1031 parameters, S=1.063,

R₁=0.0488 (observed data), wR²=0.1355 (all data), largest diff. peak/

hole=0.960/ꢀ0.898 eꢄ^ꢀ3; CCDC-249524.

Complex 27a: Empirical formula C₂₇H₂₆Cl₂NOPPd, colorless, M_r=

588.76, crystal size=0.33ꢅ0.22ꢅ0.07 mm, monoclinic, space group P2₁/n,

a=9.6858(1),

b=16.8205(1),

c=15.2823(1) ꢄ,

b=91.308,

V=

2489.15(3) ꢄ³, Z=4, 1_calcd=1.571 Mgm^ꢀ3, m=1.045 mm^ꢀ1, q range for

data collection=3.21 to 31.518, 65806 reflections, 8279 independent re-

flections, 7930 observed reflections [I>2s(I)], empirical absorption cor-

rection (multiscan method), 300 parameters, S=1.088, R₁=0.0200 (ob-

served data), wR²=0.0493 (all data), largest diff. peak/hole=0.629/

ꢀ0.684 eꢄ^ꢀ3; CCDC-249532.

Complex 38: Empirical formula C₄₃H₄₄BCl₅F₄N₂NiP₂, yellow, M_r=973.51,

crystal size=0.22ꢅ0.18ꢅ0.08 mm, monoclinic, space group P2₁, a=

9.18310(10), b=20.86120(10), c=11.61080(10) ꢄ, b=91.758, V=

2223.24(3) ꢄ³, Z=2, 1_calcd=1.454 Mgm^ꢀ3, m=0.859 mm^ꢀ1, q range for

data collection=2.95 to 31.038, 57225 reflections, 14113 independent re-

flections, 13455 observed reflections [I>2s(I)], empirical absorption cor-

rection (multiscan method), 535 parameters, S=1.004, R₁=0.0268 (ob-

served data), wR²=0.0655 (all data), absolute structure parameter=

0.009(5), largest diff. peak/hole=0.539/ꢀ0.378 eꢄ^ꢀ3; CCDC-249525.

Complex 27b: Empirical formula C₂₈H₂₈Cl₄NPPdS, colorless, M_r=689.74,

¯

crystal size=0.06ꢅ0.03ꢅ0.02 mm, triclinic, space group P1, a=9.5008(3),

b=13.3533(5), c=14.6947(6) ꢄ, a=65.3260(10), b=83.911(2), g=

69.611(2)8,

V=1586.23(10) ꢄ³,

Z=2,

1_calcd=1.444 Mgm^ꢀ3

,

m=

Complex 42: Empirical formula C₄₂H₄₄Cl₃F₆N₂NiP₃, yellow-orange, M_r=

1.056 mm^ꢀ1, q range for data collection=2.29 to 25.008, 22092 reflections,

948.76, crystal size=0.12ꢅ0.09ꢅ0.04 mm, triclinic, space group P1, a=

¯

1850

ꢃ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

www.chemeurj.org

Chem. Eur. J. 2005, 11, 1833 – 1853

Carbene Complexes

FULL PAPER

12.18140(10), b=17.50240(10), c=21.3701(2) ꢄ, a=71.21, b=82.00, g=

89.918, V=4266.78(6) ꢄ³, Z=4, 1_calcd=1.477 Mgm^ꢀ3, m=0.815 mm^ꢀ1, q

range for data collection=2.92 to 27.508, 95991 reflections, 19569 inde-

pendent reflections, 15204 observed reflections [I>2s(I)], Gaussian ab-

sorption correction (T_min/max=0.91/0.98), 1037 parameters, S=1.013, R₁=

0.0521 (observed data), wR²=0.1290 (all data), largest diff. peak and

hole=2.198 and ꢀ1.151 eꢄ^ꢀ3; CCDC249527.

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in.

The CCDC data contain the supplementary crystallographic data for this

paper. These data can be obtained free of charge from The Cambridge

Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif

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Generous financial support by the Deutsche Forschungsgemeinschaft

(Leibniz award program), the Fonds der Chemischen Industrie, and the

Deutsch-Israelische Projektkooperation (DIP program) is gratefully ac-

knowledged.

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Chem. Eur. J. 2005, 11, 1833 – 1853

Carbene Complexes

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Received: September 11, 2004

Published online: January 26, 2005

Chem. Eur. J. 2005, 11, 1833 – 1853

www.chemeurj.org

ꢃ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

1853

Article Doi

Diaminocarbene- and Fischer-carbene complexes of palladium and nickel by oxidative insertion: Preparation, structure, and catalytic activity

DOI: 10.1002/chem.200400928

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