Transition metal complexes of bulky, electron-rich N-phosphanyl-substituted N-heterocyclic carbenes (NHCP ligands). Small bite angle four-membered (κ-C,κ-P) chelate structures

Article abstract of DOI:10.1021/om300963t

Bulky, electron-rich N-phosphanyl-substituted N-heterocyclic carbenes (NHCP ligands: ^EtCNP 3, ^MesCNP 5a, ^DippCNP 5b) are potential ligands for strained, very small bite angle four-membered transition metal chelate complexes with (κ-C,κ-P) metal coordination. Various compounds of this type have been synthesized and were fully characterized inter alia by X-ray crystallography. Reactions of isolated NHCP species 3, 5a, and 5b with appropriate metal precursors furnished a series of (κ-C,κ-P)- coordinated four-membered NHCP chelate complexes for the metals of the nickel triad and for ruthenium. The cis-dimethyl Pd(II) complex (^MesCNP- κC,κ-P)PdMe₂ (8) reacted at room temperature with acceptor-substituted alkenes such as fumaronitrile and maleic anhydride to yield the corresponding η²-olefin complexes 9 and 10 with reductive elimination of ethane. Palladacyclopentadiene complex 11 was formed by addition of two equivalents of dimethyl acetylene dicarboxylate to complex 8 via alkyne-alkyne coupling.

Full text of DOI:10.1021/om300963t

Article
pubs.acs.org/Organometallics
Transition Metal Complexes of Bulky, Electron-Rich N‑Phosphanyl-
Substituted N‑Heterocyclic Carbenes (NHCP Ligands). Small Bite
Angle Four-Membered (κ‑C,κ‑P) Chelate Structures
Philipp Nagele,† Ulrike Herrlich (nee Blumbach),† Frank Rominger,† and Peter Hofmann*,†,‡
́
̈
†Organisch-Chemisches Institut, Universitat Heidelberg, INF 270, D-69120 Heidelberg, Germany
̈
‡Catalysis Research Laboratory (CaRLa), Universitat Heidelberg, INF 584, D-69120 Heidelberg, Germany
̈
S
* Supporting Information
ABSTRACT: Bulky, electron-rich N-phosphanyl-substituted
N-heterocyclic carbenes (NHCP ligands: EtCNP 3, MesCNP
5a, DippCNP 5b) are potential ligands for strained, very small
bite angle four-membered transition metal chelate complexes
with (κ-C,κ-P) metal coordination. Various compounds of this
type have been synthesized and were fully characterized inter
alia by X-ray crystallography. Reactions of isolated NHCP
species 3, 5a, and 5b with appropriate metal precursors
furnished a series of (κ-C,κ-P)-coordinated four-membered
NHCP chelate complexes for the metals of the nickel triad and
for ruthenium. The cis-dimethyl Pd(II) complex (MesCNP-
κC,κ-P)PdMe2 (8) reacted at room temperature with acceptor-
substituted alkenes such as fumaronitrile and maleic anhydride to yield the corresponding η2-olefin complexes 9 and 10 with
reductive elimination of ethane. Palladacyclopentadiene complex 11 was formed by addition of two equivalents of dimethyl
acetylene dicarboxylate to complex 8 via alkyne−alkyne coupling.
knowledge, so far only complexes with five-membered,10,11 six-
INTRODUCTION
■
membered,12 or even larger13 NHCP-type chelate ligands have
Since the first applications of NHC ligands in coordination
1
been published.
̈
chemistry by Wanzlick and Ofele and the first isolation of a
free crystalline N-heterocyclic carbene (NHC) by Arduengo,2
N-heterocyclic carbenes have gained increasing importance in
transition metal catalysis.3 Regarding their ligand properties,
NHC ligands show a remarkable resemblance to electron-rich
alkylphosphines.4 Both are considered to be strong σ-donors
and weak π-acceptors, however with different steric character-
istics and with NHC ligands forming stronger metal−ligand
bonds. Using bulky, alkyl-substituted, electron-rich diphosphi-
nomethanes as chelating, small bite angle ligands, such as
bis(di-tert-butylphosphino)methane (dtbpm),5 we have shown
that their complexes with metals of the nickel triad or with Ru
feature unusually high reactivity in bond activation chemistry6
and catalysis, e.g., for olefin metathesis (ROMP),7 for olefin
polymerization, or CO/ethylene copolymerization.8,9 Adopting
the structural motif of four-membered bisphosphine chelate
transition metal complexation and trying to combine the
electronic characteristics of NHC ligands with those of
electron-rich phosphine moieties should lead to N-phosphan-
yl-substituted NHC hybrid ligand systems capable of forming
(κ-C,κ-P)-bound, four-membered chelate structures with
appropriate transition metal fragments. We use the general
acronym NHCP for all NHC ligands with a second, P-based
coordination site such as N-phosphanyl-substituted (or N-
phosphinomethyl-substituted10) NHCs. To the best of our
Of course chelate complexation at metals forming four-
membered chelate substructures is well known for many types
of κ2-coordinating three-atom ligand units, but there is only one
structural motif of four-membered chelate systems disclosed in
the literature, by Grotjahn et al.,14 which is closely related to the
systems we report in this paper. In the context of their studies
of bulky imidazolyl phosphane ligands for Pd chemistry, these
authors have prepared a C2-phosphanyl-substituted N-methyl-
imidazole (phosphanyl = P(t-Bu)2), which in a couple of cases
was found to bind to palladium through the P- and N-donor
atom of the imidazolyl phosphine, generating (κ-N,κ-P) four-
membered chelate structures with small N−Pd−P bite angles
between 69° and 70°.
Here we report our successful first attempts to employ a
specific group of NHCP ligands, those with a direct N-
phosphanyl link, for transition metal coordination to the metals
of the Ni triad and to Ru. We disclose the synthesis and
structural characterization of the first four-membered chelate
ring NHCP complexes with (κ-C,κ-P) metal coordination and
with extraordinarily small bite angles between 65° and 70°.
Compared to the systems of Grotjahn et al.14 the replacement
Received: October 15, 2012
Published: December 28, 2012
© 2012 American Chemical Society
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Scheme 1. Synthetic Pathways for NHCP Ligands with a N−P Linkage
of the imidazole N-donor center by a NHC carbene
(imidazolylidene) carbon is expected to significantly change
the electronic structure and thus presumably reactivity patterns
of transition metal complexes.
on route b.17a Treatment of these imidazoles with sodium
triflate and di-tert-butylchlorophosphine led to the imidazolium
salts 4a/b. The precipitation of NaCl drives the reaction to the
desired product. Full conversion is indicated by a broad signal
in the 31P NMR at 123 (4a) and 124 ppm (4b). In order to
access the free NHCP ligands MesCNP (5a) and DippCNP (5b),
the salts were treated with NaHMDS in diethyl ether. The
deprotonation process can again conveniently be followed by
1H and 31P NMR. There is also a large downfield shift of the
carbene carbon in 13C NMR from around 142 ppm to ca. 226
ppm. The NHCP derivatives 3, 5a, and 5b are colorless
crystalline solids with rather high melting points (without
decomposition), in the case of the latter two at 106 °C (5a)
and 156 °C (5b). All imidazolium salts and the free NHCPs are
air and moisture sensitive; therefore they were handled in dry
solvents and under dry argon.
As displayed in Scheme 1 (route c), the third approach to
make NHCP ligands for (κ-C,κ-P) four-membered chelate
metal coordination available, also published by Kostyuk et
al.,17b involves deprotonation of N-substituted imidazoles (or
benzimidazoles) carrying bulky N-substituents (adamantyl, t-
Bu) with n-BuLi and reaction of the resulting Li-imidazolides
with di-tert-butylchlorophosphine. Unfortunately a severe
limitation of route c lies in the observation that for imidazoles
with less bulky N-substitution (e.g., aryl) a rearrangement with
phosphanyl group migration from N to C2 is facile, while for
RCNP systems isolated in routes a and b this isomerization
requires rather high temperatures. Also in our hands attempts
to synthesize analogues of 5a and 5b in route c, for instance by
deprotonation of N-t-Bu imidazole with n-BuLi and by reaction
of the imidazolide with (t-Bu)(Me)PCl even at −40 °C, led
directly and exclusively to the rearranged product with the
phosphanyl group at C2 instead of yielding the expected
NHCP system. This clearly reveals that not only is a bulky N-
substituent of the N-substituted imidazole, which is deproto-
nated, required, as found by Kostyuk et al., but that the
substitution pattern and presumably the steric demand of the
phosphorus halide also plays an important role for route c and
the yield of the desired NHCP ligands.
RESULTS AND DISCUSSION
■
Ligand Synthesis. The first synthesis of an NHCP ligand
with a direct N−P linkage was achieved in our group some time
ago.15 The simple three-step synthetic strategy is shown in
Scheme 1 (route a).
After a modified procedure of Fischer et al.,16 imidazole was
first P-functionalized at one nitrogen with di-tert-butylchloro-
phosphine in the presence of triethylamine, yielding 1. The
reaction could be easily followed through the high-field shift of
the phosphorus singlet signal from 148 ppm to 89 ppm in 31P
NMR. Subsequent alkylation with Meerwein’s salt
(Et3O)+(BF4)− in DME at the other nitrogen gave the N-
ethyl, N′-P(t-Bu)2-substituted imidazolium salt 2. The com-
pletion of the alkylation reaction was determined by the
downfield shift of the phosphorus nucleus from 89 ppm to 121
ppm in the 31P NMR spectrum and of proton H2 (NCHN)
from 7.7 ppm to 8.8 ppm in the proton NMR. In the last step
the imidazolium salt was deprotonated with NaHMDS in Et2O
at low temperature, giving the desired NHCP system EtCNP
(3). We use the general acronym NHCP for various NHC
chelate ligands10 with a second, P-based coordination site, and
we specify the NHCP systems with an N−R unit and with
direct N−P(t-Bu)2 substitution used in the present paper as
RCNP to indicate their three-atom, four-membered (κ-C,κ-P)
chelate metal coordination. Compound 3 is characterized by a
singlet in its 31P NMR at 97 ppm and by the absence of the H2
signal in the 1H NMR. The molecular structure of compound 3
could be characterized by X-ray diffraction (vide infra). Our
route a is a modular approach toward RCNP systems, allowing a
broad variation of N-bound phosphanyl units other than P(t-
Bu)2, but is somewhat limited by the availability of appropriate
carbon electrophiles such as (Et3O)+(BF4)−, (Me3O)+(BF4)−,
CH3SO2CF3, or the like for the second N-substitution (step 2)
leading to imidazolium salts.
Recently, the group of Kostyuk et al.17a,b has disclosed two
further elegant pathways leading to bulky N-phosphanyl-
substituted N-heterocyclic NHCPs (routes b, c). In contrast
to our route a, where the carbon substituent on the N atom was
introduced in the second step by N-alkylation, we used N-aryl-
substituted imidazoles (aryl = Mes, Dipp) as starting materials
As clearly indicated by Scheme 1, NHCP ligand structures of
the RCNP type, required for our intended studies of their small
bite angle (κ-C,κ-P) metal coordination behavior, are
conveniently accessible in a reasonably broad variability. Here
we focus on EtCNP (3), MesCNP (5a), and DippCNP (5b).
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The solid-state X-ray structures of 3, 5a, and 5b could be
determined and are shown in Figure 1, and selected bond
lengths and angles are listed in Table 1.
phosphine and of the carbene unit are oriented in an anti
fashion. This geometry is similar to the one in bulky
diphosphinomethanes5d and is as expected since the electronic
repulsion between the lone pairs is minimized in this
conformation.
Synthesis of Neutral (RCNP κ-C,κ-P) Platinum Com-
plexes. Metal complexes of Pt were obtained by adding the
isolated pure carbenes 5a/b to a suspension or solution of a
suitable metal precursor such as (COD)PtCl2 or (COD)PtMe2
in THF (Scheme 2).
Scheme 2. Synthesis of Neutral (RCNP κ-C,κ-P) Platinum
Complexes
Platinum dichloro complexes 6a and 6b showed a singlet
resonance in the 31P NMR with characteristic Pt-satellites (1JP,Pt
= 3439.9 Hz for 6a, 1JP,Pt = 3440.5 Hz for 6b). Both complexes
were poorly soluble and could only be dissolved in polar aprotic
solvents such as acetonitrile or DMSO. Complex 6a was
crystallized by slow evaporation of acetonitrile and DCM out of
a saturated solution in this solvent mixture. It was not yet
possible to obtain crystals suitable for X-ray diffraction for
complex 6b.
RCNP platinum dimethyl complexes 7a and 7b also are
characterized by singlet resonances in their 31P NMR spectra at
104 and 100 ppm, respectively, with Pt-satellites. Expectedly,
the 1JP,Pt coupling constants of the dimethyl complexes (1JP,Pt
=
1279.4 Hz for 7a, 1JP,Pt = 1288.4 Hz for 7b) were much smaller
compared to those of the dichloro complexes. The different
resonances for the methyl groups cis and trans to P were
assigned by the different coupling constants from 1H, 13C NMR
3
and NOESY experiments. The coupling constants JH,P of the
methyl protons of 7a and 7b are approximately 7 Hz, whereas
the coupling constants JC,P of the methyl carbons differ a lot
and are 107 Hz for the trans-P- and 4 Hz for the cis-P-bonded
methyl group.
2
Figure 1. ORTEP diagrams of the solid-state structures of 3, 5a, and
5b with 50% ellipsoids. Hydrogen atoms (except imidazolylidene H
atoms) are omitted for clarity.
The most remarkable feature of all structures is the small
chelate bite angle, which for all three compounds is the same
within experimental error. Due to the fact that four-membered-
ring chelate ligands generally lead to small bite angles, in this
case smaller than 70°, the molecular structures of the
complexes put the platinum center in a rather distorted
square-planar geometry. This also distinctly affects the P−N2−
C1 bond angle, which decreases by metal coordination from
around 128° in the free carbenes (Table 1) to approximately
100° in the complexes (Table 2). Interestingly, no remarkable
difference between the trans influence of the NHC unit and the
P-moiety, respectively, is observed since bond lengths from
platinum to both chloro or methyl ligands are nearly identical.
Synthesis of Neutral (RCNP κ-C,κ-P) Palladium Com-
plexes. (MesCNP κ-C,κ-P)PdMe2 8 was obtained via a ligand
exchange reaction by adding the free carbene 5a to a solution of
(tmeda)PdMe2 in THF at room temperature (Scheme 3). Due
to 3J-coupling of the methyl group protons with the phosphorus
atom, the methyl ligands exhibit two doublets in the 1H NMR.
The methyl group cis to P has a larger coupling constant (8.0
Hz at −0.28 ppm) than the methyl group trans to P (6.9 Hz at
−0.25 ppm). In the 13C NMR the coupling constants are
Table 1. Selected Bond Lengths (Å) and Angles (deg) for
Ligands 3, 5a, and 5b
EtCNP (3) MesCNP (5a) DippCNP (5b)
P−N2
N2−C1
C1−N5
N5−C6/C21
P−N2−C1
N2−C1−N5
C1−N5−C6/C21
C1−N5−C6/C21−C7/C22
1.753(2)
1.386(3)
1.360(3)
1.451(3)
128.89(17)
102.1(2)
123.1(2)
95.3
1.749(2)
1.383(3)
1.359(3)
1.445(3)
127.72(17)
102.0(2)
121.9(2)
89.65
1.7485(16)
1.378(2)
1.361(2)
1.437(2)
127.57(13)
101.88(15)
123.47(15)
90.34
The N-ethyl-substituted carbene 3 displays an abnormally
large displacement parameter for the ethyl group’s methyl unit.
(See comments in the CIF file in the Supporting Information.)
The solid-state X-ray structures of the aryl-substituted
carbenes 5a and 5b show symmetric molecules with the
imidazole rings in mirror planes. Comparing the bond lengths
and angles of the three carbenes, only very small, nonsignificant
structural differences are apparent. The lone pairs of the
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Table 2. Selected Bond Lengths (Å) and Angles (deg) for
Platinum Complexes 6a, 7a, and 7b
(
MesCNP)PtCl2
(
MesCNP)PtMe2
(
DippCNP)PtMe2
(6a)
(7a)
(7b)
Pt−C1
Pt−P
1.974(8)
2.216(2)
2.349(2)
2.042(17)
2.287(4)
2.067(15)
2.048(3)
2.2767(8)
2.081(3)
Pt−Cl1/C7
(trans-P)
Pt−Cl2/C6
(trans-C)
2.357(2)
2.059(16)
2.092(3)
P−N2
N2−C1
P−Pt−C1
C1−Pt−Cl1/C7
1.747(8)
1.366(11)
69.2(3)
1.745(14)
1.388(19)
68.0(4)
1.742(3)
1.370(4)
67.90(8)
100.58(13)
87.68(15)
98.2(3)
99.4(6)
Cl1/C7−Pt−Cl2/
94.09(8)
87.4(7)
C6
P−Pt−Cl2/C6
Pt−C1−N2
Pt−P−N2
98.48(8)
106.3(6)
84.9(3)
99.5(6)
105.2(5)
105.5(10)
85.2(4)
103.84(11)
105.2(2)
85.16(10)
101.6(2)
P−N2−C1
101.1(10)
Table 3. Selected Bond Length (Å) and Angles (deg) for
Palladium Complexes 9 and 10 (for both independent
molecules)
(
MesCNP)Pd(0)FN (9)
(
MesCNP)Pd(0)MA (10)
Pd−C1
Pd−P
Pd−C7 (trans-P)
Pd−C6 (trans-C)
C6−C7
P−N2
N2−C1
P−Pd−C1
C6−Pd−C7
P−N2−C1
2.112(2)/2.114(2)
2.3261(2)/2.3205(6)
2.081(2)/2.099(2)
2.069(2)/2.057(2)
1.443(3)/1.452(3)
1.750(2)/1.742(2)
1.371(3)/1.374(3)
68.13(7)/68.01(6)
40.67(9)/40.87(9)
105.37(15)/105.20(15)
2.099(3)/2.073(3)
2.3209(7)/2.3409(7)
2.116(3)/2.101(3)
2.079(3)/2.096(3)
1.4274(4)/1.422(5)
1.744(2)/1.755(2)
1.373(3)/1.365(3)
67.93(7)/67.85(8)
39.79(11)/39.60(13)
104.57(14)/104.23(18)
such as dimethyl acetylene dicarboxylate (DMAD), affords the
palladacyclopentadiene complex 11 (Scheme 3). The product
formation is indicated by a color change from colorless to
yellowish.
The olefin complexes 9 and 10 are characterized by a singlet
in their 31P NMR at 127 and 130 ppm, respectively. The olefin
protons of complex 9 show two doublets at around 2.5 ppm in
their 1H NMR, and complex 10 displays two singlets at around
3.6 ppm for the MA protons. Since the NHCP ligand of 9 and
10 with its two very strong σ-donor coordination sites is tailor-
made for efficient back-bonding to the low-lying olefin π*-
orbitals; the olefin hydrogens are shifted to distinctly higher
field compared to the uncoordinated olefins FN and MA and
thus indicate the expected relevant contribution of a metal-
lacyclopropane resonance structure in these systems. The
palladacyclopentadiene 11 shows a signal close to the free
carbene at 99 ppm in its 31P NMR spectrum. The 1H
resonances of three methyl ester methyl groups are observed
between 3.4 and 3.5 ppm, whereas one ester signal is shifted to
higher field (2.8 ppm) as a consequence of its location over the
face of the aromatic system of the N-mesityl substituent, which
is oriented perpendicular to the NHC ring.
Figure 2. ORTEP diagrams of the solid-state structures of 6a, 7a, and
7b with 50% ellipsoids. Hydrogen atoms (except H atoms of the Pt-
bound methyl groups) are omitted for clarity.
smaller for the cis-P methyl group (4.8 Hz at −10.3 ppm) and
larger for the trans-P one (105.2 Hz at −3.8 ppm), as
anticipated.
Single crystals of 8 were obtained by slow evaporation of
diethyl ether from a saturated solution. The molecular structure
in the crystal is shown in Figure 3. The geometry around the
metal center is again distorted square planar, the bite angle is
67.59(7)°, and again no trans influence difference can be
detected; the two Pd−CH3 bond lengths, 2.066(3) (trans-P)
and 2.056(3) Å (trans-C), are practically identical (Table 4).
The dimethyl complex 8 can serve as a convenient precursor
for further transformations. Electron-poor olefins, e.g., fumaro-
nitrile (FN) and maleic anhydride (MA), induce reductive
elimination of exclusively ethane (NMR) at room temperature
and lead to the palladium(0) olefin complexes 9 and 10. The
reaction of 8 with two equivalents of an electron-poor alkyne,
Crystals of 9 and 10 could be obtained by slow evaporation
of THF and diethyl ether from a solution of the palladium
complexes and were suitable for X-ray diffraction analysis. Their
molecular structures are shown in Figure 4. In both cases two
independent molecules crystallized in the unit cell, and their
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Scheme 3. Synthesis of (RCNP κ-C,κ-P) Palladium Complexes
Figure 3. ORTEP diagram of the solid-state structures of 8 with 50%
ellipsoids. Hydrogen atoms (except H atoms of the Pd-bound methyl
groups) are omitted for clarity.
bond lengths and angles partially differ somewhat (Table 3).
The CC double bond (1.443(3)/1.452(3) Å) in the
fumaronitrile complex 9 is elongated compared to the free
olefin (1.249 Å).18 This is also observed in the maleic
anhydride complex 10, where the CC double bond
(1.427(4)/1.422(5) Å) is also longer than in the uncoordinated
olefin (1.3322(9) Å).19 This feature is clear evidence for the
above-mentioned resonance contribution of metallacyclopro-
pane character. Compound 11 was also crystallized, but the
data obtained were of moderate quality and only useful as a
proof of the overall constitution.
Figure 4. ORTEP diagrams of the solid-state structures of 9 and 10
with 50% ellipsoids. Hydrogens are omitted for clarity.
Synthesis of a Neutral NHCP Nickel Complex. The cis-
dimethyl compound (MesCNP κ-C,κ-P)NiMe2 12 was obtained
similarly to the palladium complex 8. The free carbene 5a was
reacted with (tmeda)NiMe2 in pentane at low temperature in a
heterogeneous reaction. The methyl ligands show two doublets
at −0.83 and −0.64 ppm in the 1H NMR with coupling
constants of 12.2 and 4.6 Hz. The phosphorus resonance is at
Table 4. Selected Bond Lengths (Å) and Angles (deg) for Methyl Complexes of the Nickel Triad 7a, 8, and 12
(
MesCNP)PtMe2 (7a)
(
MesCNP)PdMe2 (8)
(
MesCNP)NiMe2 (12)
M−C1
M−P
M−C7 (trans-P)
M−C6 (trans-C)
P−N2
2.042(17)
2.287(4)
2.067(15)
2.059(16)
1.745(14)
1.388(19)
68.0(4)
2.097(2)
2.3310(6)
2.066(3)
2.056(3)
1.746(2)
1.372(3)
67.59(7)
100.50(10)
87.15(11)
104.81(8)
103.71(16)
84.08(7)
104.18(16)
1.920(6)/1.946(6)
2.2508(17)/2.2363(17)
1.915(6)/1.927(6)
1.926(6)/1.952(7)
1.743(5)/1.749(5)
1.354(7)/1.370(7)
69.91(19)/70.15(19)
98.8(3)/99.2(3)
N2−C1
P−M−C1
C1−M−C7
C7−M−C6
P−M−C6
M−C1−N2
M−P−N2
P−N2−C1
99.4(6)
87.4(7)
89.4(3)/89.4(3)
105.2(5)
105.5(10)
85.2(4)
102.0(2)/101.3(2)
106.8(5)/105.7(4)
82.05(18)/83.02(17)
101.1(4)/100.8(4)
101.1(10)
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112 ppm. The complex decomposes partially in solution and
does so even as a solid at temperatures higher than −20 °C.
X-ray quality crystals of 12 could be grown out of the
reaction mixture. Again, two independent molecules are found
in the unit cell, and the structure of the complex is shown in
Figure 5. As all dimethyl complexes of the nickel triad (7a, 8,
Figure 6. ORTEP diagram of the solid-state structure of 13 with 50%
ellipsoids. Hydrogen atoms are omitted for clarity. Selected bond
lengths (Å) and angles (deg) with estimated standard derivations:
Ru−C1 = 2.073(2), Ru−P = 2.4096(5), Ru−Cl1 = 2.4466(5), P−N2
= 1.7412(18), N2−C1 = 1.370(3), P−Ru−C1 = 65.25(6), C1−Ru−
Cl1 = 79.12(6), P−Ru−Cl1 = 90.181(19), Ru−C1−N2 = 106.37(13),
Ru−P−N2 = 82.75(6), P−N2−C1 = 102.24(13).
Figure 5. ORTEP diagram of the solid-state structures of 12 with 50%
ellipsoids. Hydrogen atoms (except H atoms of the Ni-bound methyl
groups) are omitted for clarity.
dimethyl complex (8) reacted readily with electron-poor olefins
at room temperature under ethane elimination, leading to novel
Pd(0) olefin complexes. With an electron-deficient alkyne a
Pd(II) metallacyclopentadiene complex was formed. The
chemistry and in particular the potential for metal-catalyzed
reactions of this class of NHCP complexes are currently being
investigated in our lab.
12) were crystalline and could be successfully subjected to X-
ray analysis, their relevant structural data are listed in Table 4.
Compared with the corresponding platinum (7a, 68.0(4)°) and
palladium (8, 67.59(7)°) complexes, the nickel complex 12
features the largest bite angle, with 69.91(19)° and 70.15(19)°.
We interpret this as due to the fact that the bond lengths of the
ligating NHCP atoms to the Ni center are shorter, just like the
methyl to Ni distances. The geometries of the platinum (7a)
and the palladium complex (8) are quite similar and different
from the Ni compound (12).
Synthesis of a Neutral NHCP Ruthenium Complex.
The octahedral bis-chelate complex (MesCNP κ-C,κ-P)2RuCl2
13 was synthesized by the reaction of two equivalents of
MesCNP 5a with (PPh3)3RuCl2 in THF. The reaction with only
one equivalent of the free NHCP also led to the precipitation of
complex 13 and a nonseparable mixture of unidentifiable
compounds in solution.
Crystals of 13 suitable for X-ray analysis were obtained
directly from a preliminary NMR test reaction in d8-THF and
had grown in the NMR tube. The molecular structure of 13 is
shown in Figure 6. The complex has an octahedral geometry
with the two chloro ligands trans and an inversion center; hence
the two chelate ligands are arranged in trans P−P position. The
bond lengths within the coordination sphere are longer
compared to the square-planar platinum complex 6a. Especially
the Ru−P bond is around 0.2 Å longer (Ru 2.4096(5), Pt
2.216(2) Å), and therefore this complex exhibits the smallest
bite angle (65.25(6)°) of all four-membered chelate NHCP
complexes presented here.
EXPERIMENTAL SECTION
■
General Comments. All manipulations were carried out under an
atmosphere of dry argon using standard Schlenk- and syringe-cannula
techniques or in a glovebox containing dry argon and less than 1 ppm
oxygen and water. Solvents were dried over an appropriate drying
agent, distilled under an atmosphere of argon, and stored over
molecular sieves (3 Å). Di-tert-butylchlorophosphine,5d 1-mesitylimi-
dazole,20 1-(2,6-diisopropylphenyl)imidazole,20 (COD)PtCl2,21
(COD)PtMe2, (tmeda)PdMe2,22 and (tmeda)NiMe2 were prepared
23
according to the literature. NMR spectra were recorded using a Bruker
DRX 300 or DRX 500 or a Bruker AVANCE III 600 spectrometer
with both the 31P and 13C spectra being measured in the 1H decoupled
mode. Chemical shifts are given in ppm referenced to solvent (1H,
13C). Abbreviations used are s = singlet, d = doublet, t = triplet, pt =
pseudotriplet, q = quartet, dd = doublet of doublets, sept = septet, s +
sat = singlet + satellites, d + sat = doublet + satellites. Infrared spectra
were measured on a Nicolet Magna IR 550 (ATR) or on a Bruker FT-
IR Equinox 55 spectrometer in KBr pellets. Mass spectra were
recorded on a JEOL JMS-700 or Bruker ApexQe hybrid 9.4 T FT-ICR
instrument. Elemental analyses were performed in the “Mikroanaly-
tisches Laboratorium der Chemischen Institute der Universitat
̈
Heidelberg”.
1-(Di-tert-butylphosphino)imidazole (1). To a solution of
imidazole (0.68 g, 10.0 mmol) and triethylamine (1.06 g, 10.5
mmol) in Et2O (7 mL) was added a solution of di-tert-
butylchlorophosphine (1.81 g, 10.0 mmol) in Et2O (7 mL). The
reaction mixture was stirred for 24 h at room temperature. Precipitated
triethylamine hydrochloride was filtered off and extracted three times
with Et2O. The filtrate was concentrated in vacuo until dryness and was
subjected twice to a Kugelrohr distillation to give 1 as a colorless solid
CONCLUSIONS
■
Bulky, electron-rich N-phosphanyl-functionalized NHCP li-
gands (RCNP systems) are accessible in a few steps and in good
yields. Their transition metal complexes (Ni, Pd, Pt, Ru)
feature four-membered chelate (κ-C,κ-P) metal coordination
with extraordinarily small P−M−C bite angles, around 65−69°,
but these compounds are quite stable despite their apparent
ring strain. They were synthesized by the replacement of other
ligands such as COD, tmeda, or PPh3 of appropriate precursor
complexes, employing the isolated NHCP ligands. The Pd(II)
(2.04 g, 96%). 1H NMR (300.1 MHz, CDCl3): δ 1.20 (d, 18H, 3JH,P
=
12.8 Hz, CH3-tBu), 7.14 (s, 1H, CH4/5-Im), 7.18 (s, 1H, CH4/5-Im),
7.71 (s, 1H, CH2-Im). 13C{1H} NMR (75.5 MHz, CDCl3): δ 28.8 (d,
1
2JC,P = 16.0 Hz, CH3-tBu), 34.5 (d, JC,P = 34.5 Hz, Cquart-tBu), 123.1
(CH4/5-Im), 130.1 (CH4/5-Im), 144.1 (CH2-Im). 31P{1H} NMR
(101.3 MHz, CDCl3): δ 88.6 (s). MS (CI): m/z 213.2 (M+ + H),
229.3 (M+ + O + H). IR (KBr): ν (cm−1) 3120 m, 3105 m, 2960 s,
186
dx.doi.org/10.1021/om300963t | Organometallics 2013, 32, 181−191

Organometallics
Article
2864 s, 1702 w, 1633 w, 1457 s, 1371 s, 1361 s, 1230 s, 1152 s, 1066 s,
671 s, 517 s . Anal. Calcd for C11H21N2P: C, 62.24; H, 9.97; N, 13.20;
P, 14.59. Found: C, 61.97; H, 10.12; N, 13.07; P, 14.48.
bis(trimethylsilyl)amide (2.61 g, 14.2 mmol) in THF (20 mL). The
reaction mixture was stirred at this temperature for 30 min. The
solvent was removed in vacuo, and the product was extracted with
pentane (3 × 20 mL) and filtered off. The filtrate was concentrated in
vacuo until the product started to precipitate. The solution was put
into a freezer (−40 °C) for full crystallization. The solvent was filtered
off at −40 °C, and the product was dried in vacuo to give 5a as a
colorless crystalline solid (4.04 g, 86%), which was stored at −20 °C.
3-(Di-tert-butylphosphino)-1-ethylimidazolium Tetrafluorobo-
rate (2). 1 (465 mg, 2.19 mmol) and ethyl Meerwein’s salt (415
mg, 2.19 mmol) were placed in a Schlenk tube and cooled to 0 °C in
an ice bath. Then 8 mL of equally cooled DME was added, and the
reaction mixture was allowed to warm to room temperature and stirred
for 8 d. The solution was concentrated in vacuo until dryness, and the
resulting solid was washed with pentane and recrystallized from DME
at low temperatures. The product was washed twice with pentane and
dried in vacuo, to give 2 as a colorless powder (647 mg, 90%), which
1
3
Mp: 106 °C. H NMR (300.1 MHz, C6D6): δ 1.37 (d, 18H, JH,P
=
12.4 Hz, CH3-tBu), 2.02 (s, 6H, o-CH3-Mes), 2.14 (s, p-CH3-Mes),
4
3
6.35 (pt, 1H, JH,P = 1.5 Hz, JH,H = 1.5 Hz, CH5-Im), 6.76 (s, 2H,
3
3
CH-Mes), 7.08 (dd, 1H, JH,P = 4.8 Hz, JH,H = 1.5 Hz, CH4-Im).
1
13C{1H} NMR (75.5 MHz, C6D6): δ 16.5 (o-CH3-Mes), 21.4 (p-CH3-
was stored at −20 °C. H NMR (300.1 MHz, CD2Cl2): δ 1.26 (d,
18H, 3JH,P = 13.5 Hz, CH3-tBu), 1.57 (t, 3H, 3JH,H = 7.4 Hz, CH3-Et),
4.43 (q, 2H, 3JH,H = 7.4 Hz, CH2-Et), 7.52 (d, 1H, J = 1.6 Hz, CH4/5-
Im), 7.60 (s, 1H, CH4/5-Im), 9.02 (s, 1H, CH2-Im). 13C{1H} NMR
(75.5 MHz, CD2Cl2): δ 15.7 (CH3-Et), 28.7 (d, 2JC,P = 16.0 Hz, CH3-
tBu), 35.6 (d, 1JC,P = 30.0 Hz, Cquart-tBu), 46.1 (CH2-Et), 123.7 (CH4/
5-Im), 127.3 (CH4/5-Im), 141.3 (CH2-Im). 31P{1H} NMR (121.5
MHz, CD2Cl2): δ 120.6 (s). MS (ESI MS/MS): m/z 241.2 (M+),
184.4 (M+ − tBu), 97.2 (M+ − P(tBu)2). IR (KBr): ν (cm−1) 3133 s,
2997 s, 2962 s, 1571 m, 1527 m, 1475 s, 1371 m, 1174 m, 1125 vs,
1098 vs, 1014 vs, 807 m, 770 m, 650 m, 502 m. Anal. Calcd for
C13H26BF4N2P: C, 47.58; H, 7.99; N, 8.54; P, 9.44. Found: C, 47.08;
H, 7.90; N, 8.70; P, 9.41.
2
1
Mes), 29.4 (d, JC,P = 16.1 Hz, CH3-tBu), 35.3 (d, JC,P = 24.1 Hz,
Cquart-tBu), 119.3 (d, JC,P = 8.0 Hz, CH5-Im), 128.4 (d, JC,P = 35.1
3
2
Hz, CH4-Im), 129.4 (CH-Mes), 135.6 (Cquart-Mes), 137.5 (Cquart
-
Mes), 139.5 (Cquart-Mes), 225.8 (Ccarbene). 31P{1H} NMR (101.3 MHz,
C6D6): δ 99.9 (s). MS (HR-FAB+): m/z 331.2290 (M+ + 1). IR
(ATR): ν (cm−1) 3138 w, 2946 m, 2855 m, 1585 w, 1493 m, 1460 m,
1361 m, 1238 w, 1170 s, 1124 s, 1077 s, 1032 w, 1009 m, 922 m, 850 s,
808 s, 740 vs. Anal. Calcd for C20H31N2P: C, 72.69; H, 9.46; N, 8.48;
P, 9.37. Found: C, 72.49; H, 9.55; N, 8.55; P, 9.33.
3-(Di-tert-butylphosphino)-1-(2,6-di-isopropylphenyl)-
imidazolium Triflate (4b). To a solution of 1-(2,6-diisopropylphenyl)-
imidazole (5.71 g, 25.0 mmol) and sodium triflate (4.73 g, 27.5 mmol,
1.1 equiv) in THF (40 mL) was added dropwise at −20 °C di-tert-
butylchlorophosphine (5.21 g, 27.5 mmol, 1.1 equiv). The reaction
mixture was allowed to warm slowly to room temperature and stirred
for 48 h. After evaporation of the solvent the product was extracted
with CH2Cl2 (3 × 30 mL) and filtered off. The filtrate was
concentrated in vacuo until dryness and washed with pentane (2 ×
40 mL) to give 4b as colorless powder (8.34 g, 64%). Mp: 186 °C. 1H
NMR (300.1 MHz, CD2Cl2): δ 1.17 (d, 6H, 3JH,H = 7.0 Hz, CH3-iPr),
3-(Di-tert-butylphosphino)-1-ethylimidazol-2-ylidene (3). To a
suspension of the salt 2 (164 mg, 0.5 mmol) in Et2O (3 mL) was
added dropwise at −20 °C over 30 min a solution of sodium
bis(trimethylsilyl)amide (92 mg, 0.5 mmol) in Et2O (2 mL). The
reaction mixture was stirred at this temperature for 30 min. The
solvent was removed in vacuo, and the product was extracted with
pentane (3 × 3 mL) and filtered off. The filtrate was concentrated in
vacuo until the product started to precipitate. The solution was put
into a freezer (−40 °C) for full crystallization. The solvent was filtered
off at −40 °C, and the product was dried in vacuo to give 3 as a
colorless crystalline solid (75 mg, 63%), which was stored at −20 °C.
1H NMR (500.1 MHz, d-THF): δ 1.21 (d, 18H, 3JH,P = 12.4 Hz, CH3-
tBu), 1.36 (t, 3H, 3JH,H = 7.3 Hz, CH3-Et), 4.08 (q, 2H, 3JH,H = 7.3 Hz,
CH2-Et), 6.93 (s, 1H, CH5-Im), 6.98 (d, 1H, 3JH,P = 3.9 Hz, CH4-Im).
3
3
1.20 (d, 6H, JH,H = 6.9 Hz, CH3-iPr), 1.33 (d, 18H, JH,P = 13.4 Hz,
CH3-tBu), 2.22 (sept, 2H, 3JH,H = 6.9 Hz, CH-iPr), 7.37 (d, 2H, 3JH,H
=
3
7.7 Hz, CH-Ar), 7.60 (t, 1H, JH,H = 7.8 Hz, CH-Ar), 7.69 (s, 1H,
CH5-Im), 8.05 (s, 1H, CH4-Im), 8.73 (s, 1H, CH2-Im). 13C{1H}
NMR (75.5 MHz, CD2Cl2): δ 24.0 (CH3-iPr), 24.5 (CH3-iPr), 28.7
(d, 2JC,P = 16.1 Hz, CH3-tBu), 29.5 (CH-iPr), 35.8 (d, 1JC,P = 30.1 Hz,
Cquart-tBu), 125.3 (2C, CH-Ar), 127.6 (CH5-Im), 128.3 (CH4-Im),
13C{1H} NMR (125.8 MHz, d-THF): δ 17.7 (CH3-Et), 29.6 (d, 2JC,P
=
1
130.2 (Cquart-Ar), 132.7 (1C, CH-Ar), 142.3 (CH2-Im), 145.5 (Cquart
-
16.2 Hz, CH3-tBu), 35.4 (d, JC,P = 35.4 Hz, Cquart-tBu), 46.5 (CH2-
Et), 117.4 (d, 3JC,P = 8.1 Hz, CH5-Im), 128.6 (d, 2JC,P = 35.7 Hz, CH4-
Im), 223.5 (Ccarbene). 31P{1H} NMR (202.5 MHz, d-THF): δ 97.2 (s).
MS (HR-EI): m/z 240.1773 (M+). Due to the sensitivity of 3, a
correct elemental analysis was not obtained.
Ar). 31P{1H} NMR (121.5 MHz, CD2Cl2): δ 123.8 (s). MS (ESI+): m/
z 373.27644 (M+). IR (ATR): ν (cm−1) 3081 w, 2963 w, 2868 w, 1508
w, 1471 w, 1369 w, 1263 vs, 1225 m, 1150 m, 1094 m, 1066 m, 1032 s,
907 w, 806 m, 783 w, 760 m, 682 w. Anal. Calcd for C24H38F3N2O3PS:
C, 55.16; H, 7.33; N, 5.36; S, 6.14; P, 5.93. Found: C, 55.08; H, 7.21;
N, 5.37; S, 5.86; P, 5.78.
3-(Di-tert-butylphosphino)-1-mesitylimidazolium Triflate (4a).
To a solution of 1-mesitylimidazole (4.66 g, 25.0 mmol) and sodium
triflate (4.73 g, 27.5 mmol, 1.1 equiv) in THF (40 mL) was added
dropwise at −20 °C di-tert-butylchlorophosphine (5.21 g, 27.5 mmol,
1.1 equiv). The reaction mixture was allowed to warm slowly to room
temperature and stirred for 24 h. After evaporation of the solvent the
product was extracted with CH2Cl2 (3 × 30 mL) and filtered off. The
filtrate was concentrated in vacuo until dryness and washed with
pentane (2 × 40 mL) to give 4a as colorless powder (10.10 g, 84%).
3-(Di-tert-butylphosphino)-1-(2,6-di-isopropylphenyl)imidazol-2-
ylidene (5b). To a suspension of the salt 4b (1.57 g, 3.0 mmol) in
Et2O (15 mL) was added dropwise at −5 °C over 30 min a solution of
sodium bis(trimethylsilyl)amide (0.58 g, 3.15 mmol) in THF (7 mL).
The reaction mixture was allowed to warm to room temperature and
stirred for 30 min. The solvent was removed in vacuo, and the product
was extracted with pentane (3 × 10 mL) and filtered off. The filtrate
was concentrated in vacuo until the product started to precipitate, and
the solution was put in a freezer (−40 °C) for full crystallization. The
solvent was filtered off at −40 °C, and the product was dried in vacuo
to give 5b as colorless crystalline solid (0.68 g, 61%), which was stored
Mp: 171 °C. 1H NMR (300.1 MHz, CD2Cl2): δ 1.32 (d, 18H, 3JH,P
=
13.7 Hz, CH3-tBu), 2.04 (s, 6H, o-CH3-Mes), 2.37 (s, p-CH3-Mes),
7.02 (s, 2H, CH-Mes), 7.61 (s, 1H, CH5-Im), 7.95 (s, 1H, CH4-Im),
8.79 (s, 1H, CH2-Im). 13C{1H} NMR (75.5 MHz, CD2Cl2): δ 17.6 (o-
1
2
at −20 °C. Mp: 156 °C. H NMR (500.1 MHz, d-THF): δ 1.12 (d,
CH3-Mes), 21.4 (p-CH3-Mes), 28.7 (d, JC,P = 16.1 Hz, CH3-tBu),
3
3
1
6H, JH,H = 6.9 Hz, CH3-iPr), 1.13 (d, 6H, JH,H = 6.9 Hz, CH3-iPr),
35.7 (d, JC,P = 30.3 Hz, Cquart-tBu), 126.4 (CH5-Im), 128.1 (CH4-
3
3
1.28 (d, 18H, JH,P = 12.2 Hz, CH3-tBu), 2.57 (sept, 2H, JH,H = 6.9
Hz, CH-iPr), 6.99 (dd, 1H, JH,P = 1.2 Hz, JH,H = 1.5 Hz, CH5-Im),
Im), 130.3 (CH-Mes), 130.7 (Cquart-Mes), 134.5 (Cquart-Mes), 142.1
(Cquart-Mes), 142.3 (CH2-Im). 31P{1H} NMR (121.6 MHz, CD2Cl2):
δ 122.7 (s). MS (ESI+): m/z 331.22987 (M+). IR (ATR): ν (cm−1)
3085 w, 2958 w, 2872 w, 2361 w, 1540 w, 1515 m, 1471 w, 1368 w,
1264 vs, 1224 m, 1152 s, 1111 s, 1065 m, 1030 vs, 864 w, 774 w, 675
m. Anal. Calcd for C21H32F3N2O3PS: C, 52.49; H, 6.71; N, 5.83; P,
6.45. Found: C, 52.65; H, 6.75; N, 5.93; P, 6.16.
3-(Di-tert-butylphosphino)-1-mesitylimidazol-2-ylidene (5a). To
a suspension of the salt 4a (6.84 g, 14.2 mmol) in Et2O (20 mL) was
added dropwise at −5 °C over 1 h a solution of sodium
4
3
3
3
7.22 (dd, 1H, JH,P = 5.0 Hz, JH,H = 1.5 Hz, CH4-Im), 7.23 (d, 2H,
3JH,H = 7.7 Hz, CH-Ar), 7.34 (t, 1H, 3JH,H = 7.7 Hz, CH-Ar). 13C{1H}
NMR (125.8 MHz, d-THF): δ 23.9 (CH3-iPr), 25.0 (CH3-iPr), 29.2
(CH-iPr), 29.6 (d, 2JC,P3 = 16.1 Hz, CH3-tBu), 35.6 (d, 1JC,P = 24.7 Hz,
Cquart-tBu), 121.2 (d, JC,P = 8.0 Hz, CH5-Im), 124.1 (2C, CH-Ar),
128.6 (d, 2JC,P = 35.6 Hz, CH4-Im), 129.3 (1C, CH-Ar), 139.7 (Cquart
-
Ar), 146.8 (Cquart-Ar), 226.4 (Ccarbene). 31P{1H} NMR (121.7 MHz, d-
THF): δ 98.7 (s). MS (ESI+): m/z 373.2805 (M+ + 1). IR (ATR): ν
187
dx.doi.org/10.1021/om300963t | Organometallics 2013, 32, 181−191

Organometallics
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(cm−1) 3134 w, 3089 w, 3052 w, 2963 s, 2865 w, 1593 w, 1495 w,
1471 s, 1382 s, 1359 m, 1254 w, 1171 s, 1107 m, 1084 vs, 1060 m,
1011 m, 956 m, 806 vs, 761 vs, 748 vs, 731 m. Anal. Calcd for
C23H37N2P: C, 74.15; H, 10.01; N, 7.52; P, 8.31. Found: C, 74.30; H,
10.06; N, 7.59; P, 8.21.
purity, probably due to some unidentified impurities, not visible in the
spectra.
(
DippCNP κ-C,κ-P)PtMe2 (7b). DippCNP 5b (62 mg, 165 μmol) was
added in portions to a solution of (COD)PtMe2 (50 mg, 150 μmol) in
THF (3 mL) and stirred for 5 h. After evaporation of the solvent, the
solid was washed with pentane (5 mL) and dried in vacuo to give 7b as
(
MesCNP κ-C,κ-P)PtCl2 (6a). MesCNP 5a (79 mg, 240 μmol) was
1
colorless powder (72 mg, 80%). Mp: 197 °C (dec). H NMR (300.1
added in portions to a suspension of (COD)PtCl2 (75 mg, 200 μmol)
in THF (3 mL) and stirred for 24 h. The solvent was filtered off, and
the solid was washed with THF (5 mL) and pentane (5 mL) and dried
in vacuo to give 6a as a colorless powder (123 mg, 88%). Mp: 305 °C
2
3
MHz, d-THF): δ −0.06 (d + sat, 3H, JH,Pt = 82.4 Hz, JH,P = 7.6 Hz,
2
3
CH3(trans−P)-Pt), 0.28 (d + sat, 3H, JH,Pt = 72.2 Hz, JH,P = 6.8 Hz,
CH3(cis−P)-Pt), 1.12 (d, 6H, 3JH,H = 6.9 Hz, CH3-iPr), 1.26 (d, 6H, 3JH,H
3
1
3
= 6.9 Hz, CH3-iPr), 1.43 (d, 18H, JH,P = 13.7 Hz, CH3-tBu), 2.65
(dec). H NMR (300.1 MHz, d-DMSO): δ 1.49 (d, 18H, JH,P = 17.0
Hz, CH3-tBu), 1.98 (s, 6H, o-CH3-Mes), 2.29 (s, p-CH3-Mes), 6.98 (s,
2H, CH-Mes), 7.30 (s, 1H, CH5-Im), 8.17 (s, CH4-Im). 13C{1H}
NMR (75.5 MHz, d-DMSO): δ 17.2 (o-CH3-Mes), 20.7 (p-CH3-
(sept, 2H, 3JH,H = 6.9 Hz, CH-iPr), 6.87 (pt, 1H, 3JH,H = 1.9 Hz, 4JH,P
=
3
1.9 Hz, CH5-Im), 7.22 (d, 2H, JH,H = 7.7 Hz, CH-Ar), 7.33 (dd, 1H
3JH,H = 1.9 Hz, JH,P = 0.9 Hz, CH4-Im), 7.38 (t, 1H JH,H = 7.7 Hz,
3
3
CH-Ar). 13C{1H} NMR (75.5 MHz, d-THF): δ −13.7 (d, JC,P = 4.3
2
2
1
Mes), 27.1 (d, JC,P = 4.6 Hz, CH3-tBu), 37.4 (d, JC,P = 13.8 Hz,
Cquart-tBu), 124.2 (CH5-Im), 124.9 (CH4-Im), 128.5 (CH-Mes),
2
Hz, CH3(cis−P)-Pt), −5.0 (d, JC,P = 106.9 Hz, CH3(trans−P)-Pt), 24.0
2
(CH3-iPr), 24.3 (CH3-iPr), 28.8 (d, JC,P = 8.1 Hz, CH3-tBu), 29.5
132.8 (Cquart-Mes), 134.1 (Cquart-Mes), 138.5 (Cquart-Mes), (Ccarbene
)
(CH-iPr), 36.3 (d, 1JC,P = 3.7 Hz, Cquart-tBu), 123.8 (d, 2JC,P = 7.5 Hz,
could not be detected due to low solubility. 31P{1H} NMR (101.3
MHz, d-DMSO): δ 85.5 (s + sat, 1JP,Pt = 3439.9 Hz). MS (HR-FAB+):
m/z 596.1270 (M+), 560.1555 (M+ − Cl). IR (ATR): ν (cm−1) 3150
w, 3091 s, 2966 s, 2921 m, 2223 w, 1610 w, 1536 m, 1470 s, 1417 m,
1395 w, 1373 m, 1316 m, 1300 m, 1172 m, 1156 s, 1098 w, 1025 w,
978 w, 914 w, 849 m, 808 w, 758 w, 729 s, 700 m, 640 m. Anal. Calcd
for C20H31Cl2N2PPt2: C, 40.27; H, 5.24; N, 4.70; P, 5.19. Found: C,
40.15; H, 5.26; N, 4.56; P, 5.34.
CH4-Im), 124.2 (CH5-Im), 124.3 (2C, CH-Ar), 130.5 (1C, CH-Ar),
2
136.2 (Cquart-Ar), 146.6 (Cquart-Ar), 176.9 (d, JC,P = 4.3 Hz, Ccarbene).
1
31P{1H} NMR (121.6 MHz, d-THF): δ 100.4 (s + sat, JP,Pt = 1288.4
Hz). MS (HR-FAB+): m/z 597.2631, (M+), 582.2443 (M+ − Me),
567.2316 (M+ − 2Me). IR (ATR): ν (cm−1) 3117 w, 2962 w, 2864 w,
2782 w, 2361 w, 1464 m, 1397 m, 1368 w, 1295 w, 1259 w, 1180 w,
1152 m, 1115 w, 1023 m, 966 w, 807 s, 765 m, 723 m, 675 w. Despite
several attempts, the microanalysis values for this compound, which
has been characterized by X-ray, are outside the range associated with
analytical purity, probably due to some unidentified impurities, not
visible in the spectra.
(
MesCNP κ-C,κ-P)PtMe2 (7a). MesCNP 5a (73 mg, 220 μmol) was
added in portions to a solution of (COD)PtMe2 (67 mg, 200 μmol) in
THF (5 mL) and stirred for 2 h. After evaporation of the solvent, the
solid was washed with pentane (5 mL) and dried in vacuo to give 7a as
(
MesCNP κ-C,κ-P)PdMe2 (8). MesCNP 5a (1.43 g, 1.43 mmol) was
1
colorless powder (98 mg, 88%). Mp: 170 °C (dec). H NMR (500.1
2
3
added in portions to a solution of (tmeda)PdMe2 (0.95 g, 3.76 mmol)
in THF (20 mL) and stirred for 4 h. After evaporating the solvent, the
solid was washed with pentane (2 × 10 mL) at 0 °C and Et2O (2 × 10
mL) at −20 °C and dried in vacuo to give 8 as a colorless powder (1.39
MHz, d-THF): δ 0.01 (d + sat, 3H, JH,Pt = 83.0 Hz, JH,P = 7.3 Hz,
2
3
CH3(trans−P)-Pt), 0.30 (d + sat, 3H, JH,Pt = 71.9 Hz, JH,P = 7.0 Hz,
CH3(cis−P)-Pt), 1.42 (d, 18H, 3JH,P = 13.7 Hz, CH3-tBu), 2.06 (s, 6H, o-
CH3-Mes), 2.30 (s, p-CH3-Mes), 6.74 (s, 1H, CH5-Im), 6.94 (s, 2H,
CH-Mes), 7.32 (s, 1H, CH4-Im). 13C{1H} NMR (125.8 MHz, d-
THF): δ −13.7 (d, 2JC,P = 4.0 Hz, CH3(cis−P)-Pt), −6.2 (d, 2JC,P = 106.7
Hz, CH3(trans−P)-Pt), 18.0 (o-CH3-Mes), 21.3 (p-CH3-Mes), 28.9 (d,
1
g, 80%), which was stored at −20 °C. Mp: 152 °C (dec). H NMR
3
(300.5 MHz, d-THF): δ −0.28 (d, 3H, JH,P = 8.0 Hz, CH3(cis−P)-Pd),
3
3
−0.25 (d, 3H, JH,P = 6.9 Hz, CH3(trans−P)-Pd), 1.41 (d, 18H, JH,P
=
13.2 Hz, CH3-tBu), 2.03 (s, 6H, o-CH3-Mes), 2.30 (s, p-CH3-Mes),
6.94 (s, 2H, CH-Mes), 6.94 (pt, 1H, JH,H = 1.8 Hz, JH,P = 1.8 Hz,
2JC,P = 8.0 Hz, CH3-tBu), 36.2 (d, JC,P = 3.4 Hz, Cquart-tBu), 122.8
1
3
4
(CH5-Im), 124.1 (d, 2JC,P = 7.5 Hz, CH4-Im), 129.6 (CH-Mes), 135.9
3
3
CH5-Im), 7.43 (pt, 1H, JH,H = 1.8 Hz, JH,P = 1.8 Hz, CH4-Im).
2
(Cquart-Mes), 136.2 (Cquart-Mes), 139.4 (Cquart-Mes), 175.9 (d, JC,P
=
13C{1H} NMR (75.5 MHz, d-THF): δ −10.3 (d, JC,P = 4.8 Hz,
2
4.6 Hz, Ccarbene). 31P{1H} NMR (101.3 MHz, d-THF): δ 104.0 (s +
2
CH3(cis−P)-Pd), −3.8 (d, JC,P = 105.2 Hz, CH3(trans−P)-Pd), 18.0 (o-
sat, JP,Pt = 1279.4 Hz). MS (HR-FAB+): m/z 555.2300 (M+),
1
2
CH3-Mes), 21.2 (p-CH3-Mes), 29.0 (d, JC,P = 10.4 Hz, CH3-tBu),
540.2095 (M+ − Me), 524.1799 (M+ − 2Me). IR (ATR): ν (cm−1)
3072 w, 3027 w, 2860 m, 2353 w, 1610 w, 1528 w, 1469 m, 1390 m,
1367 m, 1307 m, 1291 m, 1262 w, 1155 s, 1094 w, 1022 m, 972 w, 933
m, 853 s, 808 s, 734 s, 675 m. Anal. Calcd for C22H37N2PPt2: C, 47.56;
H, 6.71; N, 5.04; P, 5.57. Found: C, 47.43; H, 6.69; N, 5.00; P, 5.49.
36.5 (d, 1JC,P = 12.5 Hz, Cquart-tBu), 122.7 (d, 2JC,P = 6.9 Hz, CH4-Im),
123.3 (CH5-Im), 129.5 (CH-Mes), 135.6 (Cquart-Mes), 136.3 (Cquart
-
Mes), 139.1 (Cquart-Mes), 189.7 (Ccarbene). 31P{1H} NMR (121.5 MHz,
d-THF): δ 101.5 (s). MS (HR-FAB+): m/z 466.1461 (M+), 451.1474
(M+ − Me), 436.1200 (M+ − 2Me). IR (ATR): ν (cm−1) 3126 w,
2945 w, 2901 w, 2858 w, 1572 w, 1471 m, 1386 m, 1366 m, 1273 w,
1174 m, 1150 s, 1111 m, 1090 w, 1022 w, 931 w, 860 m, 807 m, 745 s,
732 s, 658 w. Anal. Calcd for C22H37N2PPd2: C, 56.59; H, 7.99; N,
6.00; P, 6.63. Found: C, 56.64; H, 8.11; N, 6.05; P, 6.37.
(
DippCNP κ-C,κ-P)PtCl2 (6b). DippCNP 5b (75 mg, 200 μmol) was
added in portions to a suspension of (COD)PtCl2 (75 mg, 200 μmol)
in THF (5 mL) and stirred for 24 h. The solvent was filtered off, and
the solid was washed with THF (5 mL) and pentane (5 mL) and dried
in vacuo to give 6b as a colorless powder (98 mg, 77%). Mp: 307 °C
(dec). 1H NMR (600.1 MHz, CD3CN): δ 1.12 (d, 6H, 3JH,H = 6.9 Hz,
(
MesCNP κ-C,κ-P)Pd(η2-FN) (9). MesCNP 5a (69 mg, 210 μmol) was
added in portions to a solution of (tmeda)PdMe2 (51 mg, 200 μmol)
in THF (3 mL) and stirred for 4 h. Then fumaronitrile (16 mg, 200
μmol) was added in small portions, and the reaction mixture was
stirred for 24 h. After evaporation of the solvent, the solid was washed
with pentane (3 × 5 mL) and dried in vacuo to give 9 as a pale yellow
CH3-iPr), 1.29 (d, 6H, 3JH,H = 6.9 Hz, CH3-iPr), 1.54 (d, 18H, 3JH,P
=
17.2 Hz, CH3-tBu), 2.45 (sept, 2H, 3JH,H = 6.9 Hz, CH-iPr), 6.94 (dd,
3
3
3
1H, JH,H = 2.0 Hz, JH,P = 1.0 Hz CH5-Im), 7.28 (d, 2H, JH,H = 7.7
Hz, CH-Ar), 7.47 (t, 1H 3JH,H = 7.7 Hz, CH-Ar), 7.53 (pt, 1H 3JH,H
=
2.0 Hz, JH,P = 2.0 Hz, CH4-Im). 13C{1H} NMR (150.9 MHz, d-
3
1
powder (96 mg, 93%). Mp: 176 °C (dec). H NMR (300.1 MHz, d-
2
THF): δ 1.41 (d, 9H, 3JH,P = 8.0 Hz, CH3-tBu), 1.46 (d, 9H, 3JH,P = 8.0
Hz, CH3-tBu), 2.03 (s, 3H, o-CH3-Mes), 2.08 (s, 3H, o-CH3-Mes),
CD3CN): δ 23.9 (CH3-iPr), 24.0 (CH3-iPr), 28.1 (d, JC,P = 4.9 Hz,
1
CH3-tBu), 29.6 (CH-iPr), 38.8 (d, JC,P = 13.2 Hz, Cquart-tBu), 124.4
(d, 2JC,P = 6.2 Hz, CH4-Im), 124.6 (2C, CH-Ar), 126.6 (d, 3JC,P = 2.8
Hz, CH5-Im), 131.3 (1C, CH-Ar), 133.7 (Cquart-Ar), 146.3 (Cquart-Ar),
(Ccarbene) could not be detected due to low solubility. 31P{1H} NMR
3
2.32 (s, 3H, p-CH3-Mes), 2.46 (d, 1H, JH,H = 9.3 Hz, CH-FN), 2.55
3
(d, 1H, JH,H = 9.3 Hz, CH-FN), 6.99 (s, 1H, CH-Mes), 7.02 (s, 1H,
CH-Mes), 7.32 (pt, 1H, 3JH,H = 1.9 Hz, 4JH,P = 1.9 Hz, CH5-Im), 7.65
(dd, 1H, 3JH,H = 1.9 Hz, 3JH,P = 1.1 Hz, CH4-Im). 13C{1H} NMR (75.5
MHz, d-THF): δ 18.1 (o-CH3-Mes), 18.3 (CH-FN), 21.3 (p-CH3-
Mes), 21.7 (CH-FN), 28.8 (d, 2JC,P = 9.7 Hz, CH3-tBu), 30.0 (d, 2JC,P
= 10.4 Hz, CH3-tBu), 36.6 (d, 1JC,P2 = 9.7 Hz, Cquart-tBu), 37.5 (d, 1JC,P
= 10.4 Hz, Cquart-tBu), 123.4 (d, JC,P = 5.5 Hz, CH4-Im), 125.3 (d,
3JC,P = 2.8 Hz, CH5-Im), 129.6 (CH-Mes), 130.4 (CH-Mes), 134.9
1
(101.3 MHz, CD3CN): δ 84.7 (s + sat, JP,Pt = 3440.5 Hz). MS (HR-
FAB+): m/z 602.2080 (M+ − Cl). IR (ATR): ν (cm−1) 3142 w, 3091
w, 2960 w, 2361 m, 2341 m, 1739 w, 1536 w, 1460 m, 1446 w, 1417 w,
1373 w, 1364 w, 1321 w, 1301 w, 1184 w, 1159 m, 1095 w, 974 w, 938
w, 802 m, 761 s, 700 m, 668 w. Despite several attempts, the
microanalysis values are outside the range associated with analytical
188
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Organometallics
Article
(Cquart-Mes), 136.0 (Cquart-Mes), 136.1 (Cquart-Mes), 139.5 (Cquart
-
Mes), 7.26 (s, 1H, CH4-Im). 13C{1H} NMR (75.5 MHz, d-THF): δ
Mes), 191.2 (Ccarbene). 31P{1H} NMR (121.5 MHz, d-THF): δ 126.7
(s). MS (HR-FAB+): m/z 514.1553 (M+), 436.1269 (M+ − FN). IR
(ATR): ν (cm−1) 2958, 2905, 2860, 2360 w, 2329 w, 2194 m, 1605 w,
1472 m, 1390 m, 1368 w, 1274 w, 1246 w, 1152 s, 1090 w, 1022 w,
933 w, 854 w, 807 m, 739 m, 723 m, 682 m. Anal. Calcd for
C24H33N4PPd: C, 55.98; H, 6.46; N, 10.88; P, 6.02. Found: C, 56.13;
H, 6.52; N, 10.87; P, 5.74.
−10.4 (CH3(cis−P)-Ni), −3.8 (d, JC,P = 74.0 Hz, CH3(trans−P)-Ni), 18.0
2
2
(o-CH3-Mes), 21.2 (p-CH3-Mes), 30.0 (d, JC,P = 9.0 Hz, CH3-tBu),
36.8 (d, 1JC,P = 10.1 Hz, Cquart-tBu), 121.5 (d, 2JC,P = 8.3 Hz, CH4-Im),
123.7 (CH5-Im), 129.4 (CH-Mes), 135.7 (Cquart-Mes), 136.4 (Cquart
-
Mes), 138.9 (Cquart-Mes), 187.9 (d, JC,P = 2.8 Hz, Ccarbene). 31P{1H}
NMR (121.5 MHz, d-THF): δ 112.5 (s). MS (HR-FAB+): m/z
403.1496 (M+ − Me). IR (KBR): ν [cm−1] 2960 m, 2917 m, 2865 m,
1699 m, 1576 m, 1478 s, 1397 m, 1285 w, 1135 s, 1024 s, 935 w, 851
w, 821 m, 669 m. Due to the pronounced thermal instability of the
compound, a correct elemental analysis could not be obtained. The
values always were outside the range associated with analytical purity,
although 12 could be characterized by X-ray.
2
(
MesCNP κ-C,κ-P)Pd(η2-MA) (10). MesCNP 5a (69 mg, 210 μmol)
was added in portions to a solution of (tmeda)PdMe2 (51 mg, 200
μmol) in THF (3 mL) and stirred for 4 h. Then maleic anhydride (20
mg, 200 μmol) was added in small portions, and the reaction mixture
was stirred for 24 h. After evaporation of the solvent, the solid was
washed with pentane (3 × 5 mL) and dried in vacuo to give 10 as a
pale orange powder (96 mg, 91%). Mp: 183 °C (dec). 1H NMR
(300.5 MHz, d-THF): δ 1.39 (d, 18H, 3JH,P = 14.3 Hz, CH3-tBu), 1.98
(s, 6H, o-CH3-Mes), 2.33 (s, 3H, p-CH3-Mes), 3.59 (s, 1H, CH-MA),
3.67 (s, 1H, CH-MA), 6.96 (s, 1H, CH-Mes), 7.03 (s, 1H, CH-Mes),
(
MesCNP κ-C,κ-P)2RuCl2 (13). MesCNP 5a (139 mg, 420 μmol) was
added in portions to a solution of (PPh3)3RuCl2 (192 mg, 200 μmol)
in THF (5 mL) and stirred for 3 d. After evaporation of the solvent,
the solid was washed with pentane (3 × 5 mL) and Et2O (3 × 5 mL)
and dried in vacuo to give 13 as a pale brown powder (100 mg, 60%).
3
4
1
7.27 (dd, 1H, JH,H = 1.9 Hz, JH,P = 2.7 Hz, CH5-Im), 7.63 (dd, 1H,
3JH,H = 1.9 Hz, 3JH,P = 1.1 Hz, CH4-Im). 13C{1H} NMR (75.5 MHz, d-
THF): δ 17.7 (o-CH3-Mes), 17.9 (o-CH3-Mes), 21.2 (p-CH3-Mes),
Mp: 236 °C (dec). H NMR (300.1 MHz, CD3CN): δ 1.31 (d, 9H,
3
3JH,P = 7.4 Hz, CH3-tBu), 1.17 (d, 9H, JH,P = 7.2 Hz, CH3-tBu), 2.02
(s, 6H, o-CH3-Mes), 2.33 (s, p-CH3-Mes), 7.09 (s, 2H, CH-Mes), 7.26
2
2
3
3
28.7 (d, JC,P = 7.6 Hz, CH3-tBu), 28.8 (d, JC1,P = 9.0 Hz, CH3-tBu),
(d, 1H, JH,H = 1.9 Hz, CH5-Im), 7.84 (d, 1H, JH,H = 1.9 Hz, CH4-
1
Im). 13C{1H} NMR (75.5 MHz, CD3CN): δ 18.6 (o-CH3-Mes), 21.1
(p-CH3-Mes), 29.3 (d, JC,P = 3.3 Hz, CH3-tBu), 29.4 (d, JC,P = 3.0
36.5 (d, JC,P = 11.1 Hz, Cquart-tBu), 37.5 (d, JC,P = 10.4 Hz, Cquart
-
2
2
2
tBu), 42.9 (CH-MA), 46.3 (CH-MA), 123.3 (d, JC,P = 6.2 Hz, CH4-
Im), 125.3 (d, 3JC,P = 2.8 Hz, CH5-Im), 129.3 (CH-Mes), 130.3 (CH-
Mes), 135.8 (Cquart-Mes), 136.4 (Cquart-Mes), 139.3 (Cquart-Mes),
173.3 (CO-MA), 190.4 (Ccarbene). 31P{1H} NMR (121.5 MHz, d-
THF): δ 130.0 (s). MS (HR-FAB+): m/z 534.1291 (M+), 506.1357
(M+ − CO), 436.1233 (M+ − MA). IR (ATR): ν (cm−1) 3138 w,
2946 w, 2893 w, 2864 w, 2357 w, 2329 w, 1789 vs, 1723 vs, 1601 w,
1471 w, 1392 m, 1334 m, 1219 s, 1174 m, 1149 s, 1060 m, 999 m, 931
w, 868 m, 803 s, 747 m, 702 s, 732 m, 683 m. Anal. Calcd for
C24H33N2O3PPd: C, 53.89; H, 6.22; N, 5.24; P, 5.79. Found: C, 53.70;
H, 6.38; N, 5.20; P, 5.57.
1
1
Hz, CH3-tBu), 40.9 (d, JC2,P = 2.3 Hz, Cquart-tBu), 41.0 (d, JC,P = 2.3
Hz, Cquart-tBu), 127.2 (pt, JC,P = 2.9 Hz, CH4-Im), 127.5 (CH5-Im),
130.7 (CH-Mes), 136.0 (Cquart-Mes), 136.4 (Cquart-Mes), 141.5 (Cquart
-
Mes), 180.4 (Ccarbene). 31P{1H} NMR (121.5 MHz, CD3CN): δ 102.8
(s). MS (HR-FAB+): m/z 831.2872 (M+), 797.3201 (M+ − Cl). IR
(ATR): ν (cm−1) 3113 w, 2950 w, 2901 w, 2860 w, 2365 w, 1601 w,
1482 w, 1383 m, 1273 s, 1145 s, 1070 w, 1025 w, 931 m, 852 m, 806
w, 703 vs. Anal. Calcd for C40H62Cl2N4P2Ru: C, 57.68; H, 7.50; N,
6.73; P, 7.44. Found: C, 57.98; H, 7.48; N, 6.56; P, 7.32.
X-ray Structure Determinations. For the X-ray diffraction
studies data sets were collected at 200 K (100 K for 3). A complete
sphere in reciprocal space was covered by narrow ω-scans in all cases.
For all data sets the intensities were corrected for Lorentz and
polarization effects, and an empirical absorption correction, based on
the Laue symmetry of the reciprocal space, was applied using SADABS
(2009/1).24 All structures were solved by direct methods and refined
against F2 with a full-matrix least-squares algorithm using the
SHELXTL (version 2008/4) software package.25 If not noted
differently below, hydrogen atoms were treated using appropriate
riding models. All structures have been deposited with the Cambridge
Crystallographic Data Centre. These data can be obtained free of
charge from the Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif.
1: colorless crystal (polyhedron), dimensions 0.40 × 0.26 × 0.08
mm3, crystal system orthorhombic, space group P21212, Z = 4, a =
14.5402(2) Å, b = 14.8124(1) Å, c = 5.9994(1) Å, V = 1292.12(3) Å3,
ρ = 1.091 g/cm3, thetamax = 27.50°, 13 446 reflections measured, 2962
unique (R(int) = 0.0340), 2684 observed (I >2σ(I)), μ = 0.18 mm−1,
Tmin = 0.93, Tmax = 0.99, 145 parameters refined, imidazole-hydrogen
atoms were refined isotropically, Flack absolute structure parameter
−0.14(11), goodness of fit 1.05 for observed reflections, final residual
values R1(F) = 0.036, wR(F2) = 0.092 for observed reflections, residual
electron density −0.19 to 0.23 e Å−3. CCDC 905608.
(
MesCNP κ-C,κ-P)Pd(C4(CO2Me)4) (11). DMAD (57 mg, 50 μL, 400
μmol) was added in portions to a solution of MesCNP-PdMe2 8 (70
mg, 150 μmol) in THF (3 mL) and stirred for 2 d. After evaporating
the solvent and the excess DMAD at 70 °C, the solid was washed with
Et2O (3 × 5 mL) and pentane (3 × 5 mL) and dried in vacuo to give
1
11 as a yellow powder (100 mg, 92%). Mp: 223 °C (dec). H NMR
(500.1 MHz, d-THF): δ 1.46 (d, 18H, 3JH,P = 14.9 Hz, CH3-tBu), 2.02
(s, 6H, o-CH3-Mes), 2.31 (s, 3H, p-CH3-Mes), 2.81 (s, 3H, CH3-O),
3.39 (s, 3H, CH3-O), 3.45 (s, 3H, CH3-O), 3.50 (s, 3H, CH3-O), 6.94
3
4
(s, 1H, CH-Mes), 7.04 (dd, 1H, JH,H = 1.9 Hz, JH,P = 1.1 Hz, CH5-
Im), 7.63 (pt, 1H, JH,H = 1.9 Hz, JH,P = 1.9 Hz, CH4-Im). 13C{1H}
3
3
NMR (125.8 MHz, d-THF): δ 18.2 (o-CH31-Mes), 21.1 (p-CH3-Mes),
2
28.9 (d, JC,P = 7.9 Hz, CH3-tBu), 38.0 (d, JC,P = 2.8 Hz, Cquart-tBu),
50.5 (CH3-O), 50.5 (CH3-O), 50.6 (CH3-O), 50.6 (CH3-O), 124.6 (d,
2JC,P = 5.1 Hz, CH4-Im), 126.7 (CH5-Im), 130.0 (CH-Mes), 135.9
(Cquart-Mes), 136.0 (Cquart-Mes), 139.1 (Cquart-Mes), 147.3 (d, JC,P
=
6.5 Hz, CC), 147.5 (d, JC,P = 6.7 Hz, CC), 164.3 (d, JC,P = 117.0
Hz, CCtrans−P), 164.9 (d, JC,P = 1.4 Hz, CO), 165.4 (d, JC,P = 8.6
Hz, CO), 167.3 (d, JC,P = 6.5 Hz, CC), 174.4 (d, JC,P = 8.3 Hz,
CO), 176.5 (d, 2JC,P = 9.5 Hz, Ccarbene), 177.6 (d, JC,P = 6.0 Hz, C
O). 31P{1H} NMR (205.5 MHz, d-THF): δ 98.7 (s). MS (HR-FAB+):
m/z 720.1850 (M+), 693.1628 (M+ − OCH3). IR (ATR): ν (cm−1)
3142 w, 2946 w, 1716 s, 1693 s, 1532 w, 1428 m, 1393 w, 1307 w,
1192 vs, 1157 vs, 1062 m, 1008 m, 934 w, 850 w, 808 w, 757 w, 690 w.
Anal. Calcd for C32H43N2O8PPd: C, 53.30; H, 6.01; N, 3.88; P, 4.30.
Found: C, 53.19; H, 5.97; N, 3.87; P, 4.48.
2: colorless crystal (polyhedron), dimensions 0.26 × 0.24 × 0.12
mm3, crystal system monoclinic, space group C2/c, Z = 8, a =
16.2513(4) Å, b = 13.7380(2) Å, c = 15.5104(3) Å, β = 93.814(1)°, V
= 3455.19(12) Å3, ρ = 1.262 g/cm3, thetamax = 25.37°, 15 061
reflections measured, 3161 unique (R(int) = 0.0401), 2412 observed
(I >2σ(I)), μ = 0.19 mm−1, Tmin = 0.95, Tmax = 0.98, 200 parameters
refined, hydrogen atom H1 at C1 refined isotropically, goodness of fit
1.03 for observed reflections, final residual values R1(F) = 0.043,
wR(F2) = 0.106 for observed reflections, residual electron density
−0.28 to 0.38 e Å−3. CCDC 905609.
(
MesCNP κ-C,κ-P)NiMe2 (12). A solution of MesCNP 5a (182 mg, 550
μmol) in pentane (3 mL) was added slowly to a suspension of
(tmeda)NiMe2 (102 mg, 500 μmol) in pentane (3 mL) at −20 °C and
was put in a freezer (−20 °C) for 2 d. The solvent was filtered off, and
the solid was washed with pentane (3 × 5 mL) at 0 °C and dried in
vacuo to give 12 as yellow solid (135 mg, 65%), which was stored at
1
−20 °C. Mp: 90 °C (dec). H NMR (300.1 MHz, d-THF): δ −0.83
3
(d, 3H, 3JH,P = 12.2 Hz, CH3-Ni), −0.64 (d, 3H, JH,P = 4.6 Hz, CH3-
3: colorless crystal (polyhedron), dimensions 0.30 × 0.23 × 0.22
mm3, crystal system monoclinic, space group P21/c, Z = 4, a =
12.3300(15) Å, b = 10.2347(12) Å, c = 10.9981(13) Å, β =
3
Ni), 1.47 (d, 18H, JH,P = 12.9 Hz, CH3-tBu), 2.06 (s, 6H, o-CH3-
Mes), 2.29 (s, p-CH3-Mes), 6.83 (s, 1H, CH5-Im), 6.92 (s, 2H, CH-
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98.157(2)°, V = 1373.9(3) Å3, ρ = 1.162 g/cm3, T = 100(2) K,
thetamax = 27.87°, 13 551 reflections measured, 3282 unique (R(int) =
values R1(F) = 0.027, wR(F2) = 0.049 for observed reflections, residual
electron density −0.73 to 0.54 e Å−3. CCDC 905617.
0.0282), 2694 observed (I >2σ(I)), μ = 0.18 mm−1, Tmin = 0.95, Tmax
=
8: colorless crystal (polyhedron), dimensions 0.28 × 0.16 × 0.09
mm3, crystal system monoclinic, space group P21/n, Z = 4, a =
7.7405(9) Å, b = 37.916(4) Å, c = 8.0646(9) Å, β = 109.008(2)°, V =
2237.8(4) Å3, ρ = 1.386 g/cm3, thetamax = 28.34°, 23 473 reflections
measured, 5565 unique (R(int) = 0.0250), 5359 observed (I >2σ(I)),
μ = 0.91 mm−1, Tmin = 0.78, Tmax = 0.92, 246 parameters refined,
goodness of fit 1.40 for observed reflections, final residual values R1(F)
= 0.037, wR(F2) = 0.077 for observed reflections, residual electron
density −0.74 to 0.84 e Å−3. CCDC 905618.
0.96, 150 parameters refined, goodness of fit 1.15 for observed
reflections, final residual values R1(F) = 0.062, wR(F2) = 0.178 for
observed reflections, residual electron density −0.48 to 0.91 e Å−3.
CCDC 905610.
4a: colorless crystal (polyhedron), dimensions 0.31 × 0.14 × 0.08
mm3, crystal system monoclinic, space group P21/c, Z = 4, a =
9.7535(15) Å, b = 25.436(4) Å, c = 10.2815(15) Å, β = 105.874(3)°, V
= 2453.5(6) Å3, ρ = 1.301 g/cm3, thetamax = 28.36°, 25 766 reflections
measured, 6109 unique (R(int) = 0.0441), 4753 observed (I >2σ(I)),
μ = 0.24 mm−1, Tmin = 0.93, Tmax = 0.98, 289 parameters refined,
goodness of fit 1.10 for observed reflections, final residual values R1(F)
= 0.066, wR(F2) = 0.148 for observed reflections, residual electron
density −0.32 to 0.50 e Å−3. CCDC 905611.
9: colorless crystal (plate), dimensions 0.41 × 0.28 × 0.07 mm3,
crystal system triclinic, space group P1, Z = 4, a = 9.6292(12) Å, b =
̅
14.9191(18) Å, c = 18.310(2) Å, α = 99.270(2)°, β = 97.460(2)°, γ =
94.770(2)°, V = 2559.5(5) Å3, ρ = 1.336 g/cm3, thetamax = 28.31°, 27
166 reflections measured, 12 589 unique (R(int) = 0.0250), 9751
observed (I >2σ(I)), μ = 0.80 mm−1, Tmin = 0.73, Tmax = 0.95, 562
parameters refined, hydrogen atoms H6 and H7 of the olefin were
refined isotropically, goodness of fit 1.02 for observed reflections, final
residual values R1(F) = 0.032, wR(F2) = 0.075 for observed reflections,
residual electron density −0.29 to 0.99 e Å−3. CCDC 905619.
10: colorless crystal (plate), dimensions 0.11 × 0.08 × 0.02 mm3,
crystal system monoclinic, space group P21/c, Z = 8, a = 37.238(2) Å,
b = 8.0707(5) Å, c = 16.9874(10) Å, β = 101.3760(10)°, V =
5005.0(5) Å3, ρ = 1.420 g/cm3, thetamax = 28.79°, data collected with a
mean redundancy of 4.38 and a completeness of 99.7% to a resolution
of 0.74 Å, 58 837 reflections measured, 12 991 unique (R(int) =
0.0395), 10 331 observed (I >2σ(I)), μ = 0.83 mm−1, Tmin = 0.91, Tmax
= 0.98, 581 parameters refined, hydrogen atoms of the coordinated
olefins were refined isotropically, goodness of fit 1.03 for observed
reflections, final residual values R1(F) = 0.037, wR(F2) = 0.078 for
observed reflections, residual electron density −0.58 to 0.79 e Å−3.
CCDC 905620.
4b: colorless crystal (needle), dimensions 0.30 × 0.03 × 0.02 mm3,
crystal system orthorhombic, space group P212121, Z = 4, a =
10.139(3) Å, b = 16.338(4) Å, c = 17.216(5) Å, V = 2852.0(13) Å3, ρ
= 1.217 g/cm3, thetamax = 25.42°, 24 175 reflections measured, 5242
unique (R(int) = 0.0876), 4011 observed (I >2σ(I)), μ = 0.22 mm−1,
Tmin = 0.94, Tmax = 1.00, 317 parameters refined, Flack absolute
structure parameter 0.34(12), goodness of fit 1.06 for observed
reflections, final residual values R1(F) = 0.064, wR(F2) = 0.133 for
observed reflections, residual electron density −0.30 to 0.36 e Å−3.
CCDC 905612.
5a: colorless crystal (polyhedron), dimensions 0.38 × 0.14 × 0.07
mm3, crystal system monoclinic, space group P21/m, Z = 2, a =
6.0223(2) Å, b = 13.6935(3) Å, c = 12.2697(4) Å, β = 94.944(1)°, V =
1008.07(5) Å3, ρ = 1.089 g/cm3, thetamax = 25.03°, 8642 reflections
measured, 1862 unique (R(int) = 0.0521), 1384 observed (I >2σ(I)),
μ = 0.14 mm−1, Tmin = 0.95, Tmax = 0.99, 122 parameters refined,
goodness of fit 1.04 for observed reflections, final residual values R1(F)
= 0.042, wR(F2) = 0.092 for observed reflections, residual electron
density −0.22 to 0.19 e Å−3. CCDC 905613.
5b: colorless crystal (polyhedron), dimensions 0.28 × 0.23 × 0.13
mm3, crystal system monoclinic, space group P21/m, Z = 2, a =
5.9579(11) Å, b = 17.518(3) Å, c = 11.241(2) Å, β = 90.984(4)°, V =
1173.1(4) Å3, ρ = 1.055 g/cm3, thetamax = 28.32°, 12 456 reflections
measured, 2984 unique (R(int) = 0.0333), 2566 observed (I >2σ(I)),
μ = 0.13 mm−1, Tmin = 0.97, Tmax = 0.98, 135 parameters refined,
goodness of fit 1.06 for observed reflections, final residual values R1(F)
= 0.047, wR(F2) = 0.121 for observed reflections, residual electron
density −0.17 to 0.40 e Å−3. CCDC 905614.
6a: colorless crystal (polyhedron), dimensions 0.46 × 0.07 × 0.02
mm3, crystal system orthorhombic, space group Pnma, Z = 4, a =
27.553(4) Å, b = 11.6443(16) Å, c = 8.6785(12) Å, V = 2784.3(7) Å3,
ρ = 1.657 g/cm3, thetamax = 28.33°, 27 994 reflections measured, 3637
unique (R(int) = 0.0633), 3253 observed (I >2σ(I)), μ = 5.53 mm−1,
Tmin = 0.19, Tmax = 0.90, 187 parameters refined, goodness of fit 1.25
for observed reflections, final residual values R1(F) = 0.052, wR(F2) =
0.109 for observed reflections, residual electron density −5.07 to 2.38
e Å−3. CCDC 905615.
12: yellow crystal (polyhedron), dimensions 0.14 × 0.09 × 0.06
mm3, crystal system monoclinic, space group Cc, Z = 8, a =
17.0836(12) Å, b = 17.1274(12) Å, c = 18.0587(13) Å, β =
97.331(2)°, V = 5240.7(6) Å3, ρ = 1.154 g/cm3, thetamax = 20.84°, data
collected with a mean redundancy of 9.07 and a completeness of
98.3% to a resolution of 1.00 Å, 25 367 reflections measured, 5259
unique (R(int) = 0.0528), 4608 observed (I >2σ(I)), μ = 0.81 mm−1,
Tmin = 0.89, Tmax = 0.95, 524 parameters refined, Flack absolute
structure parameter 0.008(15), goodness of fit 1.04 for observed
reflections, final residual values R1(F) = 0.039, wR(F2) = 0.079 for
observed reflections, residual electron density −0.21 to 0.41 e Å−3.
CCDC 905621.
13: red-brown crystal (polyhedron), dimensions 0.25 × 0.11 × 0.09
mm3, crystal system monoclinic, space group P21/n, Z = 2, a =
12.0530(13) Å, b = 13.9007(15) Å, c = 12.3697(13) Å, β =
104.854(2)°, γ = 90°, V = 2003.2(4) Å3, ρ = 1.381 g/cm3, thetamax
=
28.44°, 21 064 reflections measured, 5020 unique (R(int) = 0.0465),
4356 observed (I >2σ(I)), μ = 0.64 mm−1, Tmin = 0.86, Tmax = 0.94,
226 parameters refined, goodness of fit 1.08 for observed reflections,
final residual values R1(F) = 0.036, wR(F2) = 0.078 for observed
reflections, residual electron density −0.29 to 0.58 e Å−3. CCDC
905700.
7a: colorless crystal (platte), dimensions 0.28 × 0.06 × 0.02 mm3,
crystal system monoclinic, space group P21/c, Z = 4, a = 19.916(11) Å,
b = 8.120(4) Å, c = 15.056(8) Å, β = 108.867(10)°, V = 2304(2) Å3, ρ
= 1.602 g/cm3, thetamax = 25.79°, 18 474 reflections measured, 4354
unique (R(int) = 0.1310), 3183 observed (I >2σ(I)), μ = 6.17 mm−1,
Tmin = 0.28, Tmax = 0.89, 240 parameters refined, goodness of fit 1.05
for observed reflections, final residual values R1(F) = 0.084, wR(F2) =
0.162 for observed reflections, residual electron density −4.53 to 2.65
e Å−3. CCDC 905616.
ASSOCIATED CONTENT
■
S
* Supporting Information
This material is available free of charge via the Internet at
http://pubs.acs.org.
7b: colorless crystal (polyhedron), dimensions 0.26 × 0.24 × 0.14
mm3, crystal system monoclinic, space group P21/n, Z = 4, a =
13.1842(2) Å, b = 9.1134(2) Å, c = 23.1448(4) Å, β = 105.3170(10)°,
V = 2682.13(9) Å3, ρ = 1.480 g/cm3, thetamax = 27.48°, 26 845
reflections measured, 6145 unique (R(int) = 0.0477), 4951 observed
(I >2σ(I)), μ = 5.30 mm−1, Tmin = 0.34, Tmax = 0.52, 279 parameters
refined, goodness of fit 1.05 for observed reflections, final residual
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: ph@oci.uni-heidelberg.de.
Notes
The authors declare no competing financial interest.
190
dx.doi.org/10.1021/om300963t | Organometallics 2013, 32, 181−191

Organometallics
Article
2008, 27, 1187. (c) Danopoulos, A. A.; Tsoureas, N.; Macgregor, S. A.;
Smith, C. Organometallics 2007, 26, 253.
ACKNOWLEDGMENTS
■
The authors thank the Deutsche Forschungsgemeinschaft (SFB
623 “Molecular Catalysts: Structure and Functional Design”)
for financial support and for a fellowship to U.H. (DFG
Graduate College 850) as well as BASF SE for Pd and Pt
precursor compounds. The Catalysis Research Laboratory
(CaRLa) is jointly funded by the University of Heidelberg,
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