Dinuclear Nickel Complexes as Catalysts
Organometallics, Vol. 24, No. 1, 2005 97
Table 1. Crystal Data and Data Collection
Parameters for 1
formula
C54H51N5P4Ni2
1010.28
P1h
fw
space group
cryst syst
triclinic
12.8286(10)
13.5102(11)
14.9130(12)
81.9030(10)
85.7970(10)
74.0030(10)
2458.2(3)
2
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
dcalc, g cm-3
1.366
cryst dimens, mm
temperature, K
F000
0.2 × 0.2 × 0.1
100(2)
1052
Figure 1. ORTEP diagram (thermal ellipsoid 50%) for
complex [Ni2(µ2-dppa)2(CNCH3)2(µ-CNCH3)], 1. The phenyl
rings are omitted for clarity. Selected bond length (Å) and
angles (deg): Ni(1)-Ni(2), 2.5174(9); Ni(1)-P(1), 2.1694(14);
Ni(2)-P(2), 2.1876(15); Ni(1)-C(49), 1.905(5); Ni(2)-C(49),
1.914(5); Ni(1)-C(53), 1.822(5); Ni(2)-C(51), 1.803(6); P(3)-
N(5), 1.706(4); P(4)-N(5), 1.710(4); C(49)-N(1), 1.220(7);
N(1)-C(50), 1.446(8); C(53)-N(3), 1.146(7); N(3)-C(54),
1.425(8); C(51)-N(2), 1.163(8); N(2)-C(52), 1.423(10). P(1)-
Ni(1)-P(4), 113.02(5); P(2)-Ni(2)-P(3), 110.04(6); C(53)-
Ni(1)-C(49), 95.0(2); C(51)-Ni(2)-C(49), 101.8(3); C(53)-
Ni(1)-Ni(2), 141.87(17); C(51)-Ni(2)-Ni(1), 148.3(2); P(3)-
N(5)-P(4), 115.8(2); P(2)-N(4)-P(1), 117.3(2).
GOF
0.964
final R indices [I > 2σ(I)], R1
0.0531
wave E500 spectrometer of the Elexsys Series at 5 K in frozen
THF. Density functional calculations (DFT) were done using
a hybrid functional developed by Becke11 along with Perdew
and Wang correlation,12 using the LANL2DZ basis set (b3pw91/
LanL2DZ) as implemented in Gaussian98.13
[Ni2(µ2-dppa)2(µ2-CNMe)(CNMe)2], 1. To a solution of
dppa (286 mg, 2.54 mmol) was added Ni(COD)2 (700 mg, 2.54
mmol) dissolved in 20 mL of toluene. The solution was stirred
for 5 min, and then 2.4 mL of a THF solution containing CNMe
(7.2 mmol, 10% molar excess) was added. The solution was
stirred for 1 h, and then the volume was reduced to 5 mL under
vacuum. The product was precipitated as a red solid upon
addition of excess pentane. The product was collected by
filtration and washed with several portions of pentane and
then dried under vacuum. Anal. Calcd for C54H51N5P4Ni2: C,
64.14; H, 5.04. Found: C, 64.25; H, 5.39. 31P NMR (toluene-
CIF file for complex 1 has been deposited with the
Cambridge Crystallographic Database (Deposition Number
212125). These data can be obtained free of charge via
12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223
336033; e-mail: deposit@ccdc.cam.ac.uk).
1
d8): 69.5 (s). H NMR (toluene-d8): 2.95 (s, 6H, Me), 2.12 (s,
3H, Me). IR (KBr) ν(NC): 2080, 1723 cm-1
.
[Ni2(µ2-dppa)2(µ2-CNR)(CNR)2] (n-Bu, 2; xylyl, 3). Com-
plexes 2 and 3 were synthesized using the same procedure as
for complex 1, but with an isocyanide/Ni(COD)2 ratio of 3:2.
Complex 2. Anal. Calcd for C63H69N5P4Ni2: C, 66.53; H,
6.07. Found: C, 66.25; H, 6.23. 31P NMR (benzene-d6): 68.58
(s). 1H NMR (benzene-d6): 3.5 (m, 4H, CH2), 2.75 (m, 8H, CH2),
Results and Discussion
Synthesis. Dppa reacts with Ni(COD)2 in the pres-
ence of aryl and alkyl isocyanides (CNR) to give the
dinuclear nickel complexes Ni2(µ2-dppa)2(µ2-CNR)-
(CNR)2 in good yield. These complexes are isoelectronic
and similar overall to dppm-bridged dimers reported
earlier.14-16 All of the complexes are air sensitive. They
were fully characterized by 31P and 1H NMR, elemental
analysis, and IR. Like the dppm analogues, the different
isocyanide ligands do not affect the 31P NMR chemical
shift (69 ( 1 ppm) significantly, indicating that the
orbitals involving the phosphorus nickel bonds do not
interact appreciably with those involved in nickel-
isocyanide bonding.
Molecular Structure of Complex 1. The structure
of 1, Figure 1, appears similar to its dppm analogue
Ni2(µ2-dppm)2(µ2-CNCH3)(CNCH3)2.17 Complex 1 has a
“W-frame” or “cradle” type structure with two µ-bridging
dppa ligands between the nickel atoms and three
isocyanide ligands, of which two are terminal and one
is bridging to the two metal centers. Crystal data and
data collection parameters for complex 1 are sum-
marized in Table 1.
1.8 (m, 9H, CH3). IR (KBr) ν(NC): 2074, 1723, 1710 cm-1
.
Complex 3. Anal. Calcd for C75H69N5P4Ni2: C, 70.29; H,
5.39. Found: C, 70.38; H, 5.26. 31P NMR (benzene-d6): 69.5
(s). 1H NMR (benzene-d6): 2.478 (s, 6H, Me), 1.907 (s, 12H,
Me), 6.6 (m, Ph), 6.87 (m, Ph), 7.15 (m, Ph), 7.35 (m, Ph), 7.79
(br, Ph). IR (KBr) ν(NC): 2038, 1833, 1745 cm-1
.
X-ray Experimental. Intensity data were collected on a
Nonius Kappa CCD diffractometer using graphite-monochro-
mated Mo KR (λ ) 0.71073 Å) radiation in the Wyckoff ω scan
mode. The structures were solved by direct methods, and all
of the non-hydrogen atoms were refined with anisotropic
thermal parameters. Refinement was by full-matrix least-
squares methods on F2. Calculations were performed using the
program SHELXTL-PC. Phenyl rings were treated as idealized
D6h symmetric rings with d(C-C) ) 1.395 Å and (C-C-C)
) 120°. Crystal data and details of measurements and refine-
ments are summarized in Table 1.
(11) Becke, A. D. J. Chem. Phys. 1993, 98, 5648.
(12) Perdew, W.; Perdew, J. P.; Wang, Y. Phys. Rev. B 1992, 45,
13244.
(13) Frisch, M. J.; Trucks, G. W.; Schlegal, H. B.; Gill, P. M. W.;
Johnson, B. G.; Robb, M. A.; Cheesman, J. R.; Keith, T.; Petersson, G.
A.; Montgomery, J. A.; Raghavachari, K.; Al-Laham, M. A.; Zakrzewski,
V. G.; Ortiz, J. V.; Foreman, J. B.; Peng, C. Y.; Ayala, P. Y.; Chen, W.;
Wong, M. W.; Andres, J. L.; Replogle, E. S.; Comperts, R.; Martin, R.
L.; Fox, D. J.; Binkley, J. S.; Defrees, D. J.; Baker, J.; Strwart, J. P.;
Head-Gordon, M.; Gonzalez, C.; Pople, J. A. Gaussian 94, revision B.3;
Gaussian, Inc.: Pittsburgh, PA, 1995.
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C. P. Inorg. Chem. 1990, 29, 4022.
(15) DeLaet, D. L.; Del Rosario, R.; Fanwick, P. E.; Kubiak, C. P. J.
Am. Chem. Soc. 1987, 109, 754-758.
(16) Gong, J.; Kubiak, C. P. Ph.D. Thesis, Purdue University, 1990;
p 181.
(17) DeLaet, D. L.; Fanwick, P. E.; Kubiak, C. P. Organometallics
1986, 5, 1807-1811.