Synthesis, Spectroscopic Characteristics, and Crystal Structure of μ-Diphenylsilylene(decacarbonyl)ditungsten Complex (μ-SiPh 2)W2(CO)10

Article abstract of DOI:10.1021/om030512x

Photolysis of W(CO)₆ in the presence of Ph₂SiH ₂ in n-heptane leads to the formation of the first μ-silyleneditungsten complex (μ-SiPh₂)W₂(CO) ₁₀. The molecular structure of the new silylen

Full text of DOI:10.1021/om030512x

Organometallics 2003, 22, 4869-4872
4869
Syn th esis, Sp ectr oscop ic Ch a r a cter istics, a n d Cr ysta l
Str u ctu r e of µ-Dip h en ylsilylen e(d eca ca r bon yl)d itu n gsten
Com p lex (µ-SiP h 2)W2(CO)10
Agnieszka Ga¸dek, Andrzej Kochel, and Teresa Szyman´ska-Buzar*
Faculty of Chemistry, University of Wrocław, 14 F. J oliot-Curie, 50-383 Wrocław, Poland
Received J uly 1, 2003
Photolysis of W(CO)6 in the presence of Ph2SiH2 in n-heptane leads to the formation of
the first µ-silyleneditungsten complex (µ-SiPh2)W2(CO)10. The molecular structure of the
new silylene compound was established by single-crystal X-ray diffraction studies and
1
characterized by IR and H, 13C{1H}, and 29Si{1H} NMR spectroscopy. In CDCl3 solution
the silylene compound reacts with bicyclo[2.2.1]hept-2-ene to give W(CO)5(η2-C7H10) and 1,3-
cyclopentylenevinylene.
In tr od u ction
and may be considered a very important task for silicon
and organometallic chemists.
Over the past few years there have been numerous
reports concerning the preparation and structure of
transition metal complexes containing silylene ligands
SiR2.1 These compounds can be regarded as analogues
of very well-known carbene complexes.2 However, in
contrast to the well-established chemistry of transition
metal carbene complexes,2 the chemical properties of the
analogous silylene complexes remains practically un-
revealed.1 On the other hand, silylene complexes were
proposed as key intermediates in many transition
metal-catalyzed rearrangements of silicon compounds,
including dehydrogenative coupling of dihydrosilanes,3
redestribution of silanes,4 and various reactions of
silylene transfer to olefins and acetylenes.5 Therefore,
systematic investigations of transition metal silylene
complexes and their chemistry appeared to be necessary
Several methods have been employed to prepare
silylene complexes.1 The first silylene complexes were
observed in reaction between disilanes and metal car-
bonyls: Ru3(CO)12 and Os3(CO)12.6a Next, the extrusion
of SiMe2 from the disilanes HMe2Si-SiMe2R (R ) H,
CH3) via Fe2(CO)9 and Co2(CO)8 was observed.6b Fur-
thermore, reactions of dichlorosilanes with metalate
anions were used to prepare base-stabilized silylene
complexes.1c More recently several reactions have been
reported to involve the extrusion of silylene from
secondary silanes R2SiH2.1a,b,d,i
Although there have been several ditungsten com-
plexes containing bridged carbene ligands reported in
the literature,7 there have been no accounts of such
complexes with µ-silylene ligands. The formation of
silylene-bridged complexes was observed in earlier
reactions of disilanes and metal carbonyls such as
Fe2(CO)9, Ru3(CO)12, Os3(CO)12, and Co2(CO)8.6 How-
ever, up to now in the reaction of tungsten carbonyls
and R2SiH2 (R ) Et,8a Ph8b,c) only bis(µ-silyl)ditungsten
complexes were detected. Here, we report an attempt
to prepare a silylene complex of tungsten in a photo-
chemical reaction of W(CO)6 and Ph2SiH2.
* Corresponding author. Fax: +48 71 328 23 48. Tel: +48 71 375
7221. E-mail: tsz@wchuwr.chem.uni.wroc.pl.
(1) (a) Straus, D. A.; Zang, C.; Quimbita, G. E.; Grumbine, S. D.;
Heyn, R. H.; Tilley, T. D.; Reingold, A. L.; Geib, S. J . J . Am. Chem.
Soc. 1990, 112, 2673. (b) Straus, D. A.; Grumbine, S. D.; Tilley, T. D.
J . J . Am. Chem. Soc. 1990, 112, 7801. (c) Leis, C.; Wilkinson, D. L.;
Handwerker, H.; Zybill, C. Organometallics 1992, 11, 514. (d) Ueno,
K.; Sakai, M.; Ogino, H. Organometallics 1998, 17, 1138. (e) Sakaba,
H.; Tsukamoto, M.; Hirata, T.; Kabuto, C.; Horino, H. J . Am. Chem.
Soc. 2000, 122, 11511. (f) Schemedake, T. A.; Haaf, M.; Paradise, B.
J .; Millevolte, A. J .; Powell, D. R.; West, R. J . Organomet. Chem. 2001,
636, 17. (g) Ueno, K.; Asami, S.; Watanabe, N.; Ogino, H. Organome-
tallics 2002, 21, 1326. (h) Martin, M.; Sola, E.; Lahoz, F. J .; Oro, L. A.
Organometallics 2002, 21, 4027. (i) Fieldman, J . D.; Peters, J . C.; Tilley,
T. D. Organometallics 2002, 21, 4065.
(2) (a) Fisher, E. O. Adv. Organomet. Chem. 1976, 14, 1. (b) Schrock,
R. R. Acc. Chem. Res. 1979, 12, 98. (c) Schrock, R. R. J . Chem. Soc.,
Dalton Trans. 2001, 2541. (d) Herndon, J . W. Coord. Chem. Rev. 2002,
227, 1.
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Chem. 1973, 55, C7. (b) Brown-Wensley, K. A. Organometallics 1987,
6, 1590. (c) Corey, J . Y.; Chang, L. S.; Corey, E. R. Organometallics
1987, 6, 1595. (d) Chang, L. S.; Corey, J . Y. Organometallics 1989, 8,
1885.
(4) (a) Kumada, M. J . Organomet. Chem. 1975, 100, 127. (b) Curtis,
M. D.; Epstein, P. S. Adv. Organomet. Chem. 1981, 19, 213.
(5) (a) Seyferth, D.; Shannon, M. L.; Vick, S. C.; Lim, F. Organo-
metallics 1985, 4, 57. (b) Pannell, K. H.; Cervantes, J .; Hernandez, C.;
Cassias, J .; Vincenti, S. Organometallics 1986, 5, 1056. (c) Pestana,
D. C.; Koloski, T. S.; Berry, D. H. Organometallics 1994, 13, 4173. (d)
Mitchell, G. P.; Tilley, T. D.; Yap, G. P. A.; Rheingold, A. L. Organo-
metallics 1995, 14, 5472. (e) Sharma. H. K.; Pannell, K. H. Chem. Rev.
1995, 95, 1351.
Resu lts a n d Discu ssion
Upon photolysis of W(CO)6 (1.4 mmol) and Ph2SiH2
(1.4 mmol) in n-heptane (80 cm3), the reaction solution
changed from colorless to orange, and IR spectroscopy
(6) (a) Brooks, A.; Knox, S. A. R.; Stone, F. G. A. J . Chem. Soc. A
1971, 3469. (b) Kerber, R. C.; Pakkanen, T. Inorg. Chim. Acta 1979,
37, 61.
(7) (a) Berke, H.; Ha¨rter, P.; Huttner, G.; Zsolnai, L. Chem. Ber.
1982, 115, 695. (b) Fisher, H.; Zeuner, S.; Ackerman, K. J . Chem. Soc.,
Chem. Commun. 1984, 684. (c) Sherldan, J . B.; Geoffroy, G. L.;
Rheingold, A. L. Organometallics 1986, 5, 1514. (d) Parlier, A.; Rudler,
M.; Rudler, H.; Daran, J . C. J . Organomet. Chem. 1987, 323, 353. (e)
Macomber, D. W.; Liang, M.; Rogers, R. D. Organometallics 1988, 7,
416. (f) Macomber, D. W.; Liang, M.; Madhukar, P.; Verma, A. G. J .
Organomet. Chem. 1989, 361, 187.
(8) (a) Bennett, M. J .; Simpson, K. A. J . Am. Chem. Soc. 1971, 93,
7156. (b) Butts, M. D.; Bryan, J . C. Luo, X.-L.; Kubas, G. J . Inorg.
Chem. 1997, 36, 3341. (c) Bespalova, N. B.; Bovina, M. A.; Popov, A.
V.; Mol, J . C. J . Mol. Catal. A: Chem. 2000, 160, 157.
10.1021/om030512x CCC: $25.00 © 2003 American Chemical Society
Publication on Web 10/28/2003

4870 Organometallics, Vol. 22, No. 24, 2003
Ga¸ dek et al.
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
P a r a m eter s for 1
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 1
empirical formula
C
22H10O10SiW2
atoms
distance
atoms
angle
fw
830.07
W(1)-C(1)
W(1)-C(3)
W(1)-C(2)
W(1)-C(5)
W(1)-C(4)
W(1)-Si
2.015(10)
2.018(9)
2.059(8)
2.067(9)
2.096(9)
2.577(2)
1.998(9)
2.032(9)
2.041(9)
2.051(9)
2.059(9)
2.591(2)
1.873(8)
1.884(9)
1.154(10)
1.130(9)
1.135(10)
1.129(9)
1.125(10)
1.148(9)
1.161(10)
1.147(10)
1.130(10)
C(1)-W(1)-C(3)
C(1)-W(1)-C(2)
C(3)-W(1)-C(2)
C(1)-W(1)-C(5)
C(3)-W(1)-C(5)
C(2)-W(1)-C(5)
C(1)-W(1)-C(4)
C(3)-W(1)-C(4)
C(2)-W(1)-C(4)
C(5)-W(1)-C(4)
C(1)-W(1)-Si
78.4(3)
90.1(3)
91.0(3)
92.2(3)
90.7(3)
177.4(3)
160.4(3)
82.3(3)
86.4(3)
91.8(3)
68.0(3)
146.2(3)
85.6(2)
94.2(2)
130.8(2)
79.4(3)
97.3(3)
90.5(3)
83.7(3)
91.6(3)
177.8(3)
84.4(3)
163.8(3)
90.8(3)
87.4(3)
146.0(3)
70.2(2)
97.9(2)
82.3(2)
125.5(2)
cryst size (mm)
cryst syst
space group
a (Å)
b (Å)
c (Å)
0.15 × 0.10 × 0.06
monoclinic
P21/c (No. 14)
17.0613(9)
8.9094(5)
17.7984(12)
106.115(5)
2599.2(3)
W(2)-C(8)
W(2)-C(10)
W(2)-C(6)
W(2)-C(9)
W(2)-C(7)
W(2)-Si
â (deg)
V (Å3)
Z
D
4
2.12
calcd (g/cm3)
diffractometer
radiation
Kuma KM4CCD
Mo KR (λ ) 0.71073 Å),
graphite monochromated
100
8.94
1536
C(3)-W(1)-Si
Si-C(21)
Si-C(11)
C(2)-W(1)-Si
C(5)-W(1)-Si
temp (K)
O(1)-C(1)
O(2)-C(2)
O(3)-C(3)
O(4)-C(4)
O(5)-C(5)
O(6)-C(6)
O(7)-C(7)
O(8)-C(8)
O(9)-C(9)
C(4)-W(1)-Si
µ, mm-1
C(8)-W(2)-C(10)
C(8)-W(2)-C(6)
C(10)-W(2)-C(6)
C(8)-W(2)-C(9)
C(10)-W(2)-C(9)
C(6)-W(2)-C(9)
C(8)-W(2)-C(7)
C(10)-W(2)-C(7)
C(6)-W(2)-C(7)
C(9)-W(2)-C(7)
C(8)-W(2)-Si
F(000)
data collected, θ min/max
3.72/28.45
(deg)
index ranges
-22 e h e 22, -11 e k e 11,
-16 e l e 23
17 374
no. of reflns collected
Rint
0.054
0.270/0.620
abs coeff, min./max.
refinement method
no. of data/restraints/params
final residuals: R1,
wR2 (I > 2σ(I))
full-matrix least-squares on F2
6030/0/317
0.0447, 0.0858
C(10)-W(2)-Si
C(6)-W(2)-Si
C(9)-W(2)-Si
C(7)-W(2)-Si
R1, wR2 (all data)
GOF
0.0709, 0.0942
1.06
indicated the quantitative formation of a new compound.
Its IR spectrum in n-heptane contained several strong
bands in the ν (CtO) region: 2098, 2058, 2017, 1964,
and 1948 cm-1. After evaporation of volatiles under
vacuum the residue appeared to be almost analytically
pure (SiPh2)W2(CO)10 (1). A little higher content of
carbon (Anal. Calcd 31.83 vs Found 33.21) may result
from contamination with free Ph2SiH2, which was
removed during the crystallization process. The silylene
character of the silicon ligand in 1 was proved by 29Si
NMR spectra,9 which exhibit a characteristic downfield
resonance at 211.33 ppm, and by X-ray crystal studies
(Tables 1 and 2).
As Figure 1 shows, the silylene ligand in complex 1
is almost symmetrically bonded to both tungsten atoms
with W-Si bonds of 2.577(2) and 2.591(2) Å. The bond
angles at silicon fall into three distinct groups: one
angle, C(11)-Si-C(21) ) 104.7(4)°, is close to the sp3
standard (109.5°), while two angles, C(11)-Si-W(2) and
C(21)-Si-W(1), are quite large (114.2(3)° and 115.7-
(2)°), closer to the sp2 standard (120°), whereas the
W(1)-Si-W(2) ) 78.36(7)° angle is noticeably smaller
(Table 2).
F igu r e 1. ORTEP diagram of (µ-SiPh2)W2(CO)10 (1).
The two tungsten atoms in complex 1 are separated
by 3.265(2) Å, a distance that is consistent with a W-W
bond. Only a little shorter W-W bond length was
observed in other structurally characterized dinuclear
carbonyl complexes of tungsten containing bridging
carbene or silyl ligands.7,8 For example, the W-W bond
lengths in (µ-CHPh)W2(CO)10, (µ-CHCHdCMe2)W2-
(CO)10, (µ-SiHEt2)2W2(CO)8, and (µ-SiHPh2)2W2(CO)6-
(PiPr3)2 have been reported to be 3.118(1),7b 3.1450(5),7d
3.183(1),8a and 3.2256(8) Å,8b respectively.
The W-CO bond length falls in the range 1.998(9)-
2.096(9) Å. The shortest W-CO bond distance is ob-
served for CO in the trans position to the next tungsten
atom. In the 13C NMR spectra of compound 1 the
carbonyl ligands give two very narrow resonances (δC
197.04 and 197.00), differing very much by the tungsten-
carbon coupling constant. For comparison, in the spec-
trum of the diphenylcarbene(pentacarbonyl)tungsten(0)
complex the carbonyl carbon signals were observed at
215.3 and 198.4 ppm.10
(9) (a) Kawano, Y.; Tobita, H.; Ogino, H. J . Organomet. Chem. 1992,
428, 125. (b) Corey, J . Y.; Braddock-Wilking, J . Chem. Rev. 1999, 99,
175.
(10) Casey, C. P.; Burkhardt, T. J .; Bunnell, C. A.; Calabrese, J . C.
J . Am. Chem. Soc. 1977, 99, 2127.

µ-Diphenylsilylene(decacarbonyl)ditungsten
Organometallics, Vol. 22, No. 24, 2003 4871
by 13C NMR (acetonitrile-d3) due to characteristic car-
bonyl carbon signals in a relative intensity ratio 1:4 at
δC 200.97 (1J C-W ) 157 Hz) and 197.19 (1J C-W ) 131
Hz). Other products were uncharacterized by NMR.
Sch em e 1
Further efforts to explore properties and catalytic
activity of silylene complexes of tungsten are currently
in progress.
Exp er im en ta l Section
Sch em e 2
Gen er a l Con sid er a tion s. The synthesis and manipulation
of all chemicals were carried out under nitrogen using stan-
dard Schlenk technique. Solvents and liquid reagents were
predried with CaH2 and vacuum transferred into small storage
flasks prior to use. Other chemicals, W(CO)6, Ph2SiH2, and
bicyclo[2.2.1]hept-2-ene (norbornene, NBE), were obtained
from commercial suppliers and were used as received. IR
spectra were measured with Nicolet-400 FT-IR instrument.
1H, 13C{1H}, and 29Si{1H} NMR spectra were recorded with a
Bruker AMX 500 MHz instrument. All chemical shifts are
referenced to residual solvent protons for 1H NMR (δ 7.24
CDCl3 and 1.38 cyclohexane-d12) and to the chemical shift of
the solvent for 13C NMR (δ 77.00 CDCl3 and 27.8 cyclohexane-
A possible mechanism for the formation of complex 1
is shown in Scheme 1: (i) photochemical elimination of
a carbonyl group from W(CO)6 to give W(CO)5; (ii)
oxidative addition of the Ph2SiH2 to the coordinatively
unsaturated intermediate W(CO)5 and the formation of
a seven-coordinate hydrido-silyl species; (iii) reductive
elimination of H2 and the formation of the silylene
intermediate W(CO)5(dSiPh2); (iv) coordination of W(CO)5
to the WdSi double bond and the formation of a final
µ-silyleneditungsten complex 1.
d
12). The photolysis source was an HBO 200 W high-pressure
Hg lamp. Elemental analyses were performed by the Analyti-
cal Laboratory in the Faculty of Chemistry at the University
of Wrocław with a Perkin-Elmer 2400 CHN instrument. The
analysis of the organic products was carried out on a Hewlett-
1
Packard GC-MS system as well as by H and 13C NMR.
Most of the intermediate compounds shown in Scheme
1 were uncharacterized by NMR spectroscopy. However,
in the hydride region of the 1H NMR spectrum of a crude
product the very low intensity (<0.1%) resonances at
δH -6.42 (broad), -7.14, and -7.76 were detected.
Similar hydride signals were observed during the
photochemical reaction of W(CO)6 and Ph2SiH2 in cy-
clohexane-d12 solution monitored by 1H NMR. This
suggests that an oxidative addition of Ph2SiH2 and the
formation of the hydride ligands is a key step in the
formation of silylene compound 1. However, if only
W(H)(SiHPh2)(CO)5 is formed as the intermediate
(Scheme 1), one hydride signal must be present. The
detection of the three signals suggests the reality of
concurrent reaction pathways (Scheme 2).11
An intriguing reactivity of the µ-silyleneditungsten
complex 1 was revealed in the reaction with a large
excess of bicyclo[2.2.1]hept-2-ene (norbornene) followed
in the NMR tube. In CDCl3 solution the initiation of
ring-opening metathesis polymerization (ROMP)12 of
norbornene and the formation of polynorbornene (1,3-
cyclopentylenevinylene), as well as W(CO)5(η2-C7H10),
was identified due to a characteristic olefinic proton
signal at δH 4.81.13 The appearance of a low-intensity
signal characteristic for exo-2-chloronorbornane at δH
3.87 suggests the chlorine atom transfer from chloro-
form to norbornene, during the initiation of ring-opening
metathesis polymerization. In an analogous reaction of
1 with norbornene but carried out in cyclohexane-d12
solution only W(CO)5(η2-C7H10) was detected by NMR
spectroscopy.
Syn th esis of 1. A solution of W(CO)6 (0.50 g, 1.4 mmol)
and Ph2SiH2 (0.26 g, 1.4 mmol) in freshly distilled n-heptane
(80 cm3) was irradiated through quartz at room temperature.
The course of reaction was monitored by IR measurements in
solution, and photolysis was stopped when the IR band of
W(CO)6 at 1983 cm-1 reached its minimum intensity (about 5
h). The volatile materials were then stripped off the reaction
mixture under reduced pressure at room temperature. The
residue (0.6 g) was analyzed by elemental analysis (Anal. Calcd
for C22H10O10SiW2: C, 31.83; H, 1.21. Found: C, 33.21; H,
1.62), IR in KBr pellets, and NMR spectroscopy. At this stage
of the synthesis, all these methods have shown
a little
contamination with free Ph2SiH2 and the hydride intermedi-
ates (<0.1% by the integral of resonances at δH -6.42 (broad),
-7.14, and -7.76). The analytically pure crystalline 1 was
obtained during slow crystallization from CH2Cl2/pentane
(1:20) solution at -70 °C with about 80% yield. Orange single
crystals of 1 for X-ray diffraction study were grown from
CH2Cl2/toluene/pentane (1:1:6) solution at -70 °C.
Sp ectr a l Da ta for 1. IR (KBr pellet, cm-1): 2098 (s), 2056
(vs), 2032 (s), 2020 (w), 2007 (s), 1975 (vs), 1956 (vs), 1948
(vs), 1428 (w), 1090 (w), 741 (w), 698 (w), 587 (s), 565 (s), 490
(vw), 471 (vw), 444 (vw), and 428 (vw). 1H NMR (CDCl3,
25 °C): δH 7.56 (m, 2H), 7.41 (m, 3H). 13C{1H} NMR (CDCl3,
25 °C): δC 197.04 (1J C-W ) 137 Hz, 1CO), 197.00 (1J C-W
)
119 Hz, 4CO) 144.31 (1J Si-C ) 57 Hz, C1-Ph), 134.93
(2J Si-C ) 43 Hz, C2-Ph), 130.77 (C4-Ph), 127.98 (C3-Ph).
29Si{1H} NMR (CDCl3): δSi 211.33 (1J Si-W ) 54.9 Hz).
NMR Tu be Rea ction s. The solution of compound 1 (0.04
g) and norbornene (0.01 g) in CDCl3 or cyclohexane-d12 solution
1
(0.7 cm3) was periodically analyzed by H NMR over a period
of several days at room temperature. The decay of signals due
to compound 1 and norbornene and the appearance of the new
signals were observed.
In acetonitrile solution compound 1 decomposes to
give the W(CO)5(NCMe) complex, which was detected
X-r a y Cr ysta llogr a p h y. Gen er a l Con sid er a tion s. Crys-
tal data for 1 were collected at 100 K on a Kuma KM4CCD
diffractometer with graphite-monochromated Mo KR radiation,
generated from a Glass Diffraction X-ray tube operated at 50
kV and 35 mA. An orange crystal with approximate dimen-
sions of 0.15 × 0.10 × 0.06 mm was cut from a larger plate.
(11) The mechanism presented in Scheme 2 has been suggested by
a reviewer of this paper, to whom we are very grateful.
(12) Ivin, K. J .; Mol, J . C. Olefin Metathesis and Metathesis
Polymerization; Academic Press: San Diego, CA, 1997.
(13) Go´rski, M.; Szyman´ska-Buzar, T. Manuscript in preparation.

4872 Organometallics, Vol. 22, No. 24, 2003
Ga¸ dek et al.
The images were indexed, integrated, and scaled using the
KUMA data reduction package.14 The experimental details
together with crystal data are given in Table 1. The structure
was solved by the heavy atom method using SHELXS9715 and
refined by the full-matrix least-squares method on all F2
data.16 All atoms were included in the refinement, with
anisotropic displacement parameters for the non-hydrogen
atoms and isotropic displacement parameters for hydrogen
atoms. The data were corrected for absorption,14 min./max.
absorption coefficients 0.270/0.620. Complex 1 crystallizes with
a molecule of solvent, which appears to be a partial molecule
of pentane. Attempts to model the solvent proved unsatisfac-
tory; thus, the solvent contribution was subtracted from the
reflection data using the program SQUEEZE.17 Crystal-
lographic data for compound 1 have been deposited at the
Cambridge Crystallographic Data Centre with deposition no.
CCDC-212597.
Ack n ow led gm en t. This work was generously sup-
ported by the Polish State Committee for Scientific
Research (KBN grant No 4T09A 19125). We are also
grateful to S. Baczyn´ski for the measurement of NMR
spectra.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and structure refinement parameters, atomic coordinates
and equivalent isotropic displacement parameters, anisotropic
displacement parameters, and bond lengths and angles, and
a figure of crystal packing. This material is available free of
charge via the Internet at http://pubs.asc.org.
(14) CrysAlis RED-CCD 166, Kuma Diffraction Software: Wrocław,
1999.
OM030512X
(15) Sheldrick, G. M. SHELXS97, Program for Crystal Structure
Solution; University of Go¨ettingen: Germany, 1997.
(16) Sheldrick, G. M. SHELXl97, Program for Crystal Structure
Refinement; University of Go¨ettingen: Germany, 1997.
(17) PLATON-A Multipurpose Crystallographic Tool Utrecht Uni-
versity; Utrecht, The Netherlands: Spek, A. L. Acta Crystallogr. Sect.
A 1990, 46, C34.