The synthesis and characterisation of some nickel(0) complexes with π-bounded vinylsilicon ligands; the molecular structure of [Ni{P(C6H5)3}2 η2-CH2=CHSi(CH3)3}]

Article abstract of DOI:10.1016/j.jorganchem.2004.06.057

Reactions of the nickel(0) complexes [Ni(cod)₂] (in the presence of PP or [Ni(PPh₃)₂C₂ H₂] with vinyl-siloxanes, -silanes or -silazanes yield, by displacement of alkene ligand, the new nickel π-complexes [Ni(PPh₃)₂(η-CH₂ =CHSi(OSiMe₃)₃)] (2), [{Ni(PPh₃)}₂ {μ-(η-{(CH₂=CH) ₂SiMe}₂O})] (4), [Ni(PPh₃) {η⁴-CH₂=CHSi(Me)₂(μ-O)} ₃] (5), [{Ni(η-CH₂=CHSiMe₂) ₂O}(η-CH₂=CHSiMe₃)] (7) and the known complexes [Ni(PPh₃)₂(η-CH₂ =CHSiMe₃)] (1), [{Ni(PPh₃)}₂ {μ-(η-(CH₂=CH)₄Si})] (3), [{Ni(PPh₃) (η-CH₂ =CHSiMe₂)₂NH}] (6) obtained by a simple one pot synthesis, more efficiently than in hitherto published reports. The X-ray crystal structure of (1) shows a trigonal planar environment around the nickel atom.

Full text of DOI:10.1016/j.jorganchem.2004.06.057

Journal of Organometallic Chemistry 689 (2004) 3075–3081
www.elsevier.com/locate/jorganchem
The synthesis and characterisation of some nickel(0) complexes with
p-bounded vinylsilicon ligands; the molecular structure
of [Ni{P(C6H5)3}2{g2-CH2‚CHSi(CH3)3}]
*
Hieronim Maciejewski , Agnieszka Sydor, Maciej Kubicki
´
Department of Organometallic Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, PL-60-780 Poznan, Poland
Received 29 June 2004; accepted 29 June 2004
Available online 4 August 2004
Abstract
Reactions of the nickel(0) complexes [Ni(cod)2] (in the presence of PP or [Ni(PPh3)2C2H4] with vinyl-siloxanes, -silanes or -silaz-
anes yield, by displacement of alkene ligand, the new nickel p-complexes [Ni(PPh3)2(g-CH2‚CHSi(OSiMe3)3)] (2), [{Ni(PPh3)}2{l-
(g-{(CH2‚CH)2SiMe}2O})] (4), [Ni(PPh3){g4-CH2‚CHSi(Me)(l-O)}3] (5), [{Ni(g-CH2‚CHSiMe2)2O}(g-CH2‚CHSiMe3)] (7)
and the known complexes [Ni(PPh3)2(g-CH2‚CHSiMe3)] (1), [{Ni(PPh3)}2{l-(g-(CH2‚CH)4Si})] (3), [{Ni(PPh3)(g-CH2‚CHS-
iMe2)2NH}] (6) obtained by a simple one pot synthesis, more efficiently than in hitherto published reports. The X-ray crystal struc-
ture of (1) shows a trigonal planar environment around the nickel atom.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Nickel complexes; Vinylsilanes; p-Complexes; X-ray crystal structure
1. Introduction
tween the silicon atom and the C‚C bond, allowing
delocalisation of electron density from the alkene p*-or-
bital onto the d orbitals of the silicon atom, which
enhanced the back-bonding component of the system.
The interest in the chemistry of transition metal com-
plexes containing vinyl derivatives of organosilicon
compounds as p-ligands is fully justified not only by
the particular nature of the bond between vinylsilicon
derivatives and transition metals, but mainly by the pos-
sible application of this kind of complexes to catalysis of
hydrosilylation processes [8–11].
Hydrosilylation is also used to a much greater extent in
industry to produce cross-linked products [12]; for exam-
ple silicone industry extensively uses highly active plati-
num complexes, e.g., Karstedt catalyst [13] containing
both bridging and chelating divinyl ligands [{Pt(g-CH2
‚CHSiMe2)2O}2{l-(g-CH2‚CHSiMe2)2O}] [14,15].
High reactivity of this complex has led to synthesis of
other Pt(0) complexes containing both divinyltetra-
methyldisiloxane (LL) and maleic anhydride, styrene
Transition metal–alkene p-complexes have attracted
much attention because of their significance in organo-
metallic synthesis and catalysis [1–4]. A lot of examples
of complexes with p-bounded ligands are known but
those containing vinyl derivatives of organosilicon com-
pounds are still rare. On the ground of traditional
Dewar–Chatt–Duncanson model [5,6] alkene–metal
centre bond could be explained in terms of ligand to
metal r donation and metal to ligand p back donation.
When vinylsilicon ligands are used in such complexes
there have been reports of their enhanced thermal stabil-
ity relative to that of their silicon-free analogues [7]. A
suggested reason for this fact invoked an interaction be-
*
Corresponding author. Tel.: +48618291366; fax: +48-61-8291-
508.
E-mail addresses: maciejm@main.amu.edu.pl, metalorg@amu.
edu.pl (H. Maciejewski).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.06.057

3076
H. Maciejewski et al. / Journal of Organometallic Chemistry 689 (2004) 3075–3081
[15] or various tertiary phosphines [16,17]. There are also
known vinylsiloxane-complexes of palladium [18,19] and
rhodium [20,21]. Besides vinylsiloxanes, vinylsilanes have
also been used for synthesis of metal p-complexes, e.g., Pt
[22,23], Fe [24–27], Ru [28], Rh [21,29–33], Co [25,34].
The TM complexes with vinylsilicon ligands include a
number of organosilicon derivative-containing nickel
complexes as well. Nickel equivalent of Karstedt catalyst
[{Ni(g-CH2‚CHSiMe2)2O}2{l-(g-CH2‚CHSiMe2)2-
O}] has been synthesised in the reaction of (trans,tran-
s,trans-cyclododeca-1,5,9-triene) nickel(0) [16,36] or
bis(cycloocta-1,5-diene) nickel(0) [37] with LL. There
are known examples of phosphine–vinylsiloxane nickel(0)
complexes [Ni(LL)(PR3)] [16,36,38]. The reaction be-
tween nickel atoms and LL under metal vapour synthesis
conditions yielded the tris(alkene) nickel(0) complex
[Ni(CH2‚CHSiMe2OSiMe2CH‚CHSiMe2)SiMe2CH‚
CH2)] [39]. Other silicon derivatives which have been
employed as ligands in nickel chemistry include vinylsil-
anes [40], e.g., (CH2‚CH)2- SiMe2 [17] and vinylsilaz-
ane [36,41]. Our recent contribution to this field has
brought the first examples of the nickel complexes with
cyclic p-vinylsilicon ligands, which have been fully
spectroscopically and structurally characterised. Cyclo-
tetrakis[vinyl(methyl)siloxane] and cyclotetrakis[vinyl-
(methyl)silazane] have been used to generate the nickel
complexes [{Ni(PR3)}2{l-(g-CH2‚CH(Me)Si(l-O))4}]
[38] and [{Ni(PR3)}2{l-(g-CH2‚CH(Me)Si(l-NH))4}]
[42], respectively, where R = Ph, C6H4Me-4, C6H11-c.
The first one is similar to the earlier described platinum
complex [14].
was added. The reaction mixture was allowed to stir for
24 h. The colour of the solution changed from orange to
brown. The volatiles were removed under vacuum to yield
brown oil which was dissolved in pentane (5 ml) and
stored at ꢀ30 ꢁC for 24 h, to yield orange crystals of 1
(0.35 g, 5.1 mmol, 95%). Orange crystals of 1, m.p. 124–
128 ꢁC (decomp.) suitable for X-ray diffraction were ob-
tained from a concentrated solution in pentane.
Anal. Found: C, 71.59; H, 9.42%. C41H42NiP2Si
Calc.: C, 72.05; H, 9.06.
1H NMR (C6D6, 298 K, 300 MHz), d(ppm): 0.07(s,
9H), 2.63(d, 1H), 2.77(m, 1H), 2.95(d, 1H), 6.97–
7.60(m, 30H).
13C NMR (C6D6, 298 K, 75.5 MHz), d(ppm): 51.91(s,
‚CH–), 57.38(s, ‚CH2), 129.18(s, Ph), 131.95(s, Ph),
134.36(s, Ph), 134.80(s, Ph).
31P NMR (C6D6, 298 K, 101.2 MHz), d(ppm):
2
32.83(dd), Jp–p = 37.3 Hz.
29Si NMR (C6D6, 298 K, 99.4 MHz), d(ppm): ꢀ4.20(s).
2.2.2. Synthesis
(OSiMe3)3)] (2)
of
[Ni(PPh3)2(g-CH2‚CHSi-
Bis(cyclooctadiene)nickel(0) [Ni(cod)2] (0.11 g, 0.4
mmol) and PPh3 (0.21 g, 0.8 mmol) were dissolved in
ethyl ether (5 ml) and to this suspension, CH2‚
CHSi(OSiMe3)3 (1.15 mmol) was added. The reaction
mixture was allowed to stir for 24 h. The colour of the
solution changed from orange to brown. The volatiles
were removed under vacuum to yield brown oil which
was dissolved in pentane (5 ml) and stored at ꢀ30 ꢁC
for 2 days, to yield pale yellow crystals (0.35 g, 0.39
mmol, 96%).
Anal. Found: C, 61.98; H, 6.85%. C47H60NiO3P2Si4
Calc.: C, 62.31; H, 6.68.
1H NMR (C6D6, 298 K, 300 MHz), d(ppm): 0.19(s,
27H), 2.20–2.43(m, 3H), 6.92–7.06(m, 18H, Ph), 7.42–
7.59(m, 12H, Ph).
The aim of this study was to synthesise and characterise
new nickel–vinylsilicon p-complexes and synthesise the
known complexes but by different, simpler and more efficient
methods using [Ni(cod)2] or [Ni(PR3)2C2H4] as precursors.
2. Experimental
13C NMR (C6D6, 298 K, 75.5 MHz), d(ppm): 2.29(s,
Me), 45.30(d, ‚CH–), 54.18(s, –CH2), 127.8–134.3(m, Ph).
31P NMR (C6D6, 298 K, 101.2 MHz), d(ppm):
30.80(dd).
2.1. General procedures
All reagents were dried and purified before use by the
usual procedures. [Ni(cod)2] and [Ni(PR3)2(CH2‚CH2)]
were prepared as described in the literature [43,44]. Or-
ganosilicon compounds were purchased from Gelest.
Other chemicals were purchased from Fluka. The
NMR spectra (1H, 13C, 31P, 29Si) were recorded on a
Varian Gemini 300 VT spectrometer. In all cases C6D6
was used as a solvent.
2.2.3. Synthesis of [{Ni(PPh3)}2{l-(g-{(CH2‚CH)4-
Si})] (3)
To a solution of 0.16 g (0.58 mmol) [Ni(cod)2] in 6 ml
of benzene, 0.15 g (0.58 mmol) PPh3 was added giving a
blood red solution. Next, 0.25 ml (1.16 mmol) of tetravi-
nylsilane (CH2‚CH)4Si was added; the colour of the so-
lution changed from red to brown. The mixture was
stirred at room temperature for 24 h. The volatiles were
removed under reduced pressure to give a brown oil
moved into pentane and filtered through Celite. After
concentration of the solution, it was left at ꢀ30 ꢁC for
2 days to yield a yellow solid (3) (0.21 g, 0.27 mmol, 92%).
Anal. Found: C, 67.39; H, 5.90%. C44H42Ni2P2Si
Calc.: C, 67.91; H, 5.44.
2.2. Synthesis of complexes
2.2.1. Synthesis of [Ni(PPh3)2(g-CH2‚CHSiMe3)] (1)
Bis(triphenylphosphine)ethylenenickel(0) [Ni(PPh3)2
C2H4] (0.33 g, 0.54 mmol) was dissolved in benzene (5
ml) and to this solution, CH2‚CHSiMe3 (1 ml, 6.9 mmol)

H. Maciejewski et al. / Journal of Organometallic Chemistry 689 (2004) 3075–3081
3077
1H NMR (C6D6, 298 K, 300 MHz), d(ppm): 2.86(dd,
4H), 3.26(dd, 4H), 3.49(m, 4H), 7.04–7.55 (m, 30H)
3J(H1–H2) = 12.8 Hz, 3J(H1–H3) = 16.6 Hz, 3J(H1–
13C NMR (C6D6, 298 K, 75.5 MHz), d(ppm): 0.01(s,
Me), 0.59(s, Me) 58.45(s, –CH‚), 63.87(s, ‚CH2),
129.4(s, Ph), 131.8(s, Ph), 132.2(s, ‚CH–), 133.8(d,
Ph), 135.8(d, Ph), 139.2(s, ‚CH2).
3
3
P) = 4.2 Hz, J(H2–P) = 12.2 Hz, J(H3–P) = 7.1 Hz.
13C NMR (C6D6, 298 K, 75.5 MHz), d(ppm): 55.25(s,
‚CH–), 64.36(s, ‚CH2), 129.30(s, Ph), 131.48(d, Ph),
132.49(d, Ph), 133.96(d, Ph).
31P NMR (C6D6, 298 K, 101.2 MHz), d(ppm):
38.15(d).
31P NMR (C6D6, 298 K, 101.2 MHz), d(ppm): 41.95(s).
2.2.6. Synthesis
SiMe2)2NH}] (6)
of
[{Ni(PPh3)(g-CH2‚CH-
2.2.4. Synthesis of [{Ni(PPh3)}2{l-(g-{(CH2‚CH)2-
SiMe}2O})] (4)
Divinyltetramethyldisilazane (1.0 ml) was added
slowly to a stirred red suspension of [Ni(cod)2] (0.56 g,
2.5 mmol) and PPh3 (0.66 g, 2.5 mmol) in diethyl ether
(10 ml) at ambient temperature, yielding a yellow solu-
tion. The reaction mixture was allowed to stir overnight
and the volatiles were removed under reduced pressure
to yield yellow oil. This was taken up into pentane
(2 · 2 ml) and filtered through Celite. Concentration of
the filtrate and cooling to ꢀ30 ꢁC yielded yellow crystals
of 6 (yield 90%), m.p. 123–128 ꢁC (dec).
To a solution of 0.14 g (0.5 mmol) [Ni(cod)2] in 7 ml
of benzene, 0.13 g (0.5 mmol) PPh3 was added giving
blood red solution. Next, 0.25 ml ( 2.5 mmol) of tetra-
vinyldimethyldisiloxane {(CH2‚CH)2SiMe}2O was
added; a colour of solution changing from red to brown.
A mixture was stirred at room temperature for 24 h. The
volatiles were removed under reduced pressure to give a
brown oil. This was taken up into pentane and filtered
through Celite. After concentration of the solution, it
was left at ꢀ30 ꢁC for 2 days to yield yellow crystals
of (4) (0.19 g, 0.23 mmol, 89%).
Anal. Found: C; 61.28; H, 6.93%. C26H34NNiPSi2
Calc.: C, 61.67; H, 6.77.
1H NMR (C6D6, 298 K, 300 MHz): d ꢀ0.07(s, 6H),
0.42(s, 6H), 2.63(dd, 2H), 2.87(m, 2H), 3.12(dd, 2H),
6.92–7.41(m, 15H), 3J(H1–H2) = 11.8 Hz, 3J(H1–
Anal. Found: C, 64.44; H, 5.75%. C46H48Ni2OP2Si2
Calc.: C, 64.82; H, 5.68.
1H NMR (C6D6, 298 K, 300 MHz), d(ppm): 0.11(s,
6H, Me), 2.84(dd, 4H), 3.18(dd, 4H), 3.29(m, 4H)
6.70–7.45(m, 30H) 3J(H1–H2) = 11.9 Hz, 3J(H1–
H3) = 15.2 Hz, J(H1–P) = 3.2 Hz, J(H2–P) = 8.8 Hz,
3J(H3–P) = 6.9 Hz.
3
3
13C NMR (C6D6, 298 K, 75.5 MHz): d 0.1(s, Me),
0.9(s, Me), 58.7(d, ‚CH–), 62.3(s, ‚CH2), 125.2–
137.1(m, Ph).
3
3
H3) = 16.4 Hz, J(H1–P) = 4.7 Hz, J(H2–P) = 10.8 Hz,
3J(H3–P) = 6.1 Hz.
13C NMR (C6D6, 298 K, 75.5 MHz), d(ppm): ꢀ1.76(s,
Me), 60.83(s, ‚CH–), 64.00(s, ‚CH2), 129.4(s, Ph),
131.8(s, Ph), 133.8(d, Ph), 135.8(d, Ph).
31P NMR (C6D6, 298 K, 101.2 MHz), d(ppm):
37.5(s).
31P NMR (C6D6, 298 K, 101.2 MHz): d 41.72(s).
29Si NMR (C6D6, 298 K, 99.4 MHz): d ꢀ1.5(d).
2.2.7. Synthesis of [{Ni(g-CH2‚CHSiMe2)2O}(g-
CH2‚CHSiMe3)] (7)
29Si NMR (C6D6, 298 K, 99.4 MHz), d(ppm):
ꢀ8.63(s).
2.2.5. Synthesis of [Ni(PPh3){g4-CH2‚CHSi(Me)(l-
O)}3] (5)
Cyclotris[vinyl(methyl)siloxane] (1.0 ml) was added
slowly to a stirred red suspension of [Ni(cod)2] (0.14 g,
0.5 mmol) and PPh3 (0.13 g, 0.5 mmol) in diethyl ether
(10 ml) at ambient temperature, yielding a yellow solu-
tion. The reaction mixture was allowed to stir overnight
and the volatiles were removed under reduced pressure
to yield a yellow oil. This was taken up into pentane
(2 · 2 ml) and filtered through Celite. Concentration of
the filtrate and cooling to ꢀ30 ꢁC yielded yellow crystals
of 5 (yield 90%).
A mixture of divinyltetramethyldisiloxane (0.54 ml,
2.4 mmol) and vinyltrimethylsilane (0.68 ml, 4.7 mmol)
was added to 0.13 g (0.47 mmol) [Ni(cod)2]. The suspen-
sion was dissolved and a yellow–orange solution was
obtained. The reaction mixture was stirred for 48 h,
and than 5 ml of ether was added (for deposition of
unreacted [Ni(cod)2]). After filtration, the volatile were
removed in vacuo to give a red oil (yield 85%).
Anal. Found: C, 44.96; H, 8.98%. Calc. for
(C13H30NiOSi3): C, 45.22; H, 8.76.
1H NMR( C6D6, 298 K, 300 MHz), d(ppm): ꢀ0.28(s,
6H), 0.46(s, 6H), 0.14(s, 9H),1.35(s, 3H),2.98–3.97(m,6H).
13C NMR (C6D6, 298 K, 75.5 MHz), d(ppm):
ꢀ1.17(s. Me), 1.86(s, Me), 67.06(s), 67.29(s), 67.49(s),
67.86(s), 68.4(s).
29Si NMR (C6D6, 298 K, 99.4 MHz), d(ppm):
ꢀ0.86(s), 4.16(s), 5.21(s).
Anal. Found: C, 55.56; H, 5.94%. Calc. for
(C27H33NiO3Si3): C, 55.96; H, 5.74.
1H NMR (C6D6, 298 K, 300 MHz), d(ppm): 0.58(s,
3H, Me), 0.66(s, 6H, Me), 2.66(td, 2H), 3.11(dd, 4H),
5.90–6.27(m, 3H), 7.04–7.77(m, 15H), 3J(H1–
H2) = 12.6 Hz, 3J(H1–H3) = 16.9 Hz, 3J(H1–P) = 4.4
2.3. X-ray structure determination of 1
All data were measured using monochromatic Mo Ka
3
3
˚
Hz, J(H2–P) = 8.8 Hz, J(H3–P) = 4.9 Hz.
radiation (k = 0.71073 A). The diffraction data were

3078
H. Maciejewski et al. / Journal of Organometallic Chemistry 689 (2004) 3075–3081
collected at 100(1) K by the x-scan technique on a
KUMA-KM4CCD diffractometer equipped with CCD
camera [45] with graphite-monochromatized Mo Ka ra-
3. Results and discussion
3.1. Synthetic studies
˚
diation (k = 0.71073 A). The temperature was controlled
by an Oxford Instruments Cryosystem cooling device.
The data were corrected for Lorentz-polarization effects
[46,47] as well as for absorption [46,48]. Accurate unit-cell
parameters were determined by a least-squares fit of 6738.
The structure was solved with SHELXS97 [49] and refined
with the full-matrix least-squares procedure on F2 by
All the known nickel–vinylsilicon complexes have
been prepared by two methods:
(i) Displacement of one or two alkene ligands from
nickel(0) complexes e.g., [Ni(C2H4)3], [Ni(CDT)], [Ni-
(cod)2] or by displacement of the bridging vinylsiloxane
ligand LL from Karstedtꢀs type complex [{Ni(LL)}2(l-
LL)], (ii) by the zinc (or alkylaluminium compounds)
reduction of the nickel(II) complexes [NiCl2(PPh3)2]
(or [Ni(acac)2]) in the presence of the vinylsilicon
ligands.
The isolation of the phosphine–nickel complexes with
cyclo-siloxane [38] and -silazane [42] from the reaction
between [Ni(cod)2], appropriate organosilicon com-
pounds and tertiary phosphines has shown that cyclo-
octadiene is a labile ligand which readily undergoes
displacement by many ligands. This reaction is now
extended to include vinylsilanes and linear vinyl-silox-
anes or -silazanes. For synthesis of these complexes
we have also used other nickel(0) complex [Ni(PPh3)2-
(C2H4)]. Platinum counterpart of the latter has been
used by Fitch for synthesis of several platinum complexes
with vinylsilicon ligands [22,23].
SHELXL97 [50]. Scattering factors incorporated in SHEL-
P
2
2 2
XL93 were used. The function
w(jFoj ꢀ jFcj ) was
minimized, with wꢀ1 = [r2(Fo)2 + (A Æ P)2 + BP] ðP ¼
½MaxðF 2o; 0Þ þ 2F 2cꢁ=3Þ. No empirical extinction correc-
tions were applied. The final values of A and B are listed
in Table 1. All non-hydrogen atoms were refined aniso-
tropically. In 1 the hydrogen atoms were found in subse-
quent DF maps and their positions and isotropic thermal
parameters were refined. Relevant crystal data are listed
in Table 1, together with refinement details.
Table 1
Crystal data, data collection and structure refinement
Compound
1
The reaction of mono-vinylsilanes with these Ni
precursors has led to the same complex [Ni(PPh3)2(g2-
CH2‚CHSiR3)]. In the first step of the reaction be-
tween [Ni(cod)2] and tertiary phosphines, only one
cyclooctadiene ligand is replaced by two molecules of
phosphine to form [Ni(PR3)2(cod)]. Phosphines stabilise
this complex similarly to [Ni(PR3)2C2H4] but olefinic
ligands in both complexes undergo displacement by
vinylsilanes, according to Scheme 1.
The displaced volatile cyclo-octadiene or ethylene
were easily removed in vacuo, providing the essentially
pure residue of the appropriate complexes 1 or 2 in
quantitative yield.
In a similar fashion, but using tetravinylsilane or tetra-
vinylsiloxane, instead of mono-vinylsilane, binuclear
nickel(0) complexes (3) and (4) were obtained. These
complexes are similar to nickel complexes with cyclo-
tetrakis[vinyl(methyl)siloxane] and cyclotetrakis[vinyl-
(methyl)silazane] which we have described earlier
[38,42]. In all of these complexes tetravinyl silicon deriva-
tives act as chelating and bridging ligands contrary
to divinylsilicon ligands which operate as chelating
(divinyl- tetramethyldisiloxane) or bridging (divinyl-
Formula
Ni(PPh3)2(CH2CHSiMe3),
683.49
Formula weight
Crystal system
Space group
Triclinic
ꢀ
P1
Unit cell dimensions
˚
a (A)
˚
9.4096(7)
10.3294(7)
20.6740(12)
98.472(5)
92.389(5)
114.480(7)
1797.0(2)
2
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
Z
Dx (g cmꢀ3
)
1.263
0.690
l (mmꢀ1
Crystal size (mm)
)
0.4 · 0.2 · 0.2
3–30
h Range (ꢁ)
hkl Range
ꢀ12 6h 612, ꢀ14 6k 613,
ꢀ28 6l 628
Reflections
Collected
unique (Rint
17750
)
8956 (0.0320)
6871
568
with I > 2r(I)
Number of parameters
Weighting scheme
A
0.020
0.80
dimethylsilane)
ligands.
Exemplary
complexes
B
[Ni(PPh3){(g4-CH2‚CHSiMe2)2O}] and [{Ni(PPh3)-
(l-(g2-CH2‚CH)2SiMe2)}2] were synthesised by the
Lappert group [16,17].
R(F) [I > 2r(I)]
wR (F2) [I > 2r(I)]
R(F) (all data)
wR (F2) (all data)
Goodness-of-fit
0.0339
0.0636
0.0480
0.0672
0.985
Very interesting is the complex [Ni(PPh3){g4-
(CH2‚CHSi(Me)(l-O)}3] (5) synthesised using cyclo-
tris[vinyl(methyl)siloxane], in which two vinyl groups
ꢀ3
˚
Max/min Dq (e A
)
0.78/ꢀ0.38

H. Maciejewski et al. / Journal of Organometallic Chemistry 689 (2004) 3075–3081
3079
Scheme 1.
are coordinated to the metal centre but the third one is
still free. Besides vinyl-silanes and -siloxanes, we have
also used divinyltetramethyldisilazane for synthesis of
phosphine–nickel–vinylsilicon complexes. Complexes
of this type have been synthesised previously by zinc
reduction of [NiCl2(PPh3)2] in the presence of vinylsilaz-
ane [36,41]. Our method of synthesis is more convenient
and leads to the complex [Ni(PPh3){g4-CH2‚CHSi-
(Me)}2NH] (6) obtained in a high yield.
[Ni(cod)2] can also be a good nickel precursor for
synthesis of non-phosphine complexes. Earlier, we have
described a synthesis of nickel equivalent of Karstedt
catalyst [{Ni(g-CH2‚CHSiMe2)2O}2{l-(g-CH2‚CH-
SiMe2)2O}] [37]. The bridging divinyldisiloxane ligand
in this complex can be replaced by other ligands, how-
ever, it is not necessary to isolate Karstedt type catalyst
because in direct equimolar reaction between [Ni(cod)2],
divinyltetramethyldisiloxane and other vinylsilicon
derivatives, an appropriate nickel complex is formed.
In this way, we have synthesised a few complexes (e.g.,
with styrene, maleate or fumarate derivatives), of which
[{Ni(g-CH2‚CHSiMe2)2O}(g-CH2‚CHSiMe3)] (7) is
a good example;
All kinds of analyses of the synthesised complexes 1–7
have brought satisfactory results. In the 1H NMR spectra
of complexes 1–7, the signals assigned to the vinyl protons
are in the expected region 2–3.5 ppm which is a typical of
nickel p-complexes. The signals assigned to free vinyl
groups at 5–6.5 ppm are not observed, except for the spec-
trum of complex 5, in which, due to the one non-coordi-
nated vinyl group, the signal at 5.90–6.27 ppm occurred.
The signals assigned to the protons of phosphine co-
ligands in complexes 1–6 appear in expected regions and
have expected intensities.
The 13C NMR spectra of all complexes have confirmed
the formation of p-complexes by the signals assigned to
the coordinated vinyl groups in the region 50–65 ppm.
Additionally for the complex 5 the signals at 130–140
ppm from non-coordinated vinyl group were observed.
The31PNMRspectroscopicdataforthecomplexessyn-
thesisedillustratetheusualshifttoahigherfrequencyonco-
ordination of the phosphine ligands, due to deshielding
effects, however, the shift is smaller for the complexes 1
and 2, with monovinylsilanes, then for the complexes with
multi-vinylligands.
Also in the 29Si NMR spectra, the signals are
shifted to a higher frequency as compared to those
for the free ligands.
[Ni(cod)2] + {CH2=CHSi(Me2)}2O + CH2=CHSiMe3
3.2. The X-ray molecular structure of [Ni{P(C6H5)3}2-
{g2-CH2CHSi(CH3)3}] (1)
Me
Me
Si
ð1Þ
Ni
O
+ 2 cod
Si
Me
SiMe3
The majority of nickel–alkene complexes stabilised by
tertiary phosphines adopt a trigonal shape. To the best
Me
(7)

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H. Maciejewski et al. / Journal of Organometallic Chemistry 689 (2004) 3075–3081
of our knowledge, complex 1 is the first example of a fully
characterised nickel complex with mono-vinylsilane as a
ligand.
Anisotropic ellipsoid representation of molecule 1 is
presented in Fig. 1. Table 2 lists relevant geometrical
parameters.
The phenyl rings are almost ideally planar (maximum
˚
deviation from the least square plane is 0.020(2) A).
Their mutual arrangement can be described by the dihe-
dral angles between their planes or by the dihedral an-
gles between the phenyl ring and the P–Ni–P plane.
The latter values in 1 are low (mean values are 63ꢁ).
The middlepoint of the double bond was considered
as a coordination centre. In complex 1 the coordination
number of the central Ni atom is 3, and nickel lies very
4. Conclusions
˚
close (0.036(1)A) to the plane defined by P1, P2 and X
(middlepoint of the double C‚C bond) – so the coordi-
nation is trigonal.
(1) [Ni(cod)2] and [Ni(PR3)2C2H4] are a good starting
materials for synthesis of various nickel(0) com-
plexes containing vinyl-siloxanes, -silanes or -sila-
zanes as ligands.
It has been found that Ni–P distances in the crystal
structures show the bimodal distribution with the mean
˚
values around 2.187 and 2.321 A, without apparent
(2) New nickel(0) complexes (2, 4, 5, 7) were fully, spec-
troscopically characterised. The other complexes
(1, 3, 6) were synthesised by a simple, more efficient
method than described in the literature.
chemical distinction between these two groups [51].
The Ni–P distances in 1 belong to the group with shorter
˚
bond lengths (2.16–2.17 A).
(3) The complex [Ni(PPh3)2(g-CH2‚CHSiMe3)] (1) is
the first example of nickel complex with mono-
vinylsilane whose crystal structure has been
determined.
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre: No. CCDC 232294. Copies of this infor-
mation may be obtained free of charge from: The Direc-
tor, CCDC, 12 Union Road, Cambridge, CB2 1EZ,
UK. Fax: +44-1223-336-033, e-mail: deposit@ccdc.cam.
ac.uk, or http://www.ccdc.cam.ac.uk.
Acknowledgements
Fig. 1. Anisotropic ellipsoid representation of complex 1. The ellip-
soids are drawn at 50% probability level, hydrogen atoms are depicted
as spheres with arbitrary radii. X1 is the middlepoints of C‚C bonds.
The authors thank to Professor Bogdan Marciniec
for helpful and stimulating discussions.
Table 2
˚
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1
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