Oligo(alkynylsilanes): Templates for organometallic polymers

Article abstract of DOI:10.1021/om970298a

A series of compounds containing alkynylsilane and arylsilane groups, including oligomers and polymers, were used as transition-metal ligands. The alkyne groups could be complexed by dicobalt hexacarbonyl. Alternatively, complexation of the aryl groups by chromium tricarbonyl readily took place. The molecular weights of these complexes ranged up to 155 000 for a silicone polymer derived complex. Mixed-metal clusters containing Cr/Mo and Cr/Co could be made by modifying the chromium derivatives with Mo₂Cp₂(CO)₆ and Co₂-(CO)₈, respectively. The model compound 20 shows an interesting self-assembly of the metals (Co and Cr, respectively) in the crystal.

Full text of DOI:10.1021/om970298a

5048
Organometallics 1997, 16, 5048-5057
Oligo(a lk yn ylsila n es): Tem p la tes for Or ga n om eta llic
P olym er s
Thomas Kuhnen, Mark Stradiotto, Ralph Ruffolo, Dagmar Ulbrich,
Michael J . McGlinchey, and Michael A. Brook*
Department of Chemistry, McMaster University, 1280 Main Street West,
Hamilton, Ontario, Canada L8S 4M1
Received April 8, 1997X
A series of compounds containing alkynylsilane and arylsilane groups, including oligomers
and polymers, were used as transition-metal ligands. The alkyne groups could be complexed
by dicobalt hexacarbonyl. Alternatively, complexation of the aryl groups by chromium
tricarbonyl readily took place. The molecular weights of these complexes ranged up to
155 000 for a silicone polymer derived complex. Mixed-metal clusters containing Cr/Mo and
Cr/Co could be made by modifying the chromium derivatives with Mo2Cp2(CO)6 and Co2-
(CO)8, respectively. The model compound 20 shows an interesting self-assembly of the metals
(Co and Cr, respectively) in the crystal.
In tr od u ction
of several different transition metals, and (iii) utilize
the flexibility of organosilane chemistry.
The preparation of organometallic polymers has re-
cently received much attention, since the presence of a
metal can dramatically affect the properties of the
material, particularly its optical and conductive proper-
ties.1 The polymeric nature of such systems confers
greater stability and better processability in comparison
to those of analogous small molecules. Some notewor-
thy examples include the poly(ferrocenylsilanes) of
Manners and co-workers,2 the ferrocenylsilicones of
Cuadrado and co-workers,3 the cobalt and iron cyclob-
utadiene complexes of Bunz and of Gleiter,4 the chro-
mium complexes that Corriu and co-workers used to
embed chromium in ceramics,5 the cobalt-containing
dendrimers of Seyferth et al.6a and Cuadrado et al.,6b,c
the polyalkynyl architectures of Diederich and co-
workers.7
The ligands of interest for this project were those
possessing alkynyl and aryl groups that provide sites
of attachment for organometallic moieties containing
molybdenum, cobalt, or chromium. In recent years, we
have reported the syntheses of a variety of metal
complexes of alkynes, monosilyl- and disilylalkynes, and
arylsilanes.9-11 Similarly, Corriu et al.12 and others13,14
have described linear polymers, while Seyferth and co-
workers have reported dendrimeric complexes of this
type.6 Complexes of Cp2Mo2(CO)4 with trimethylsilyl-
terminated alkynes and diynes also are readily pre-
pared.15,16 For the aryl complexes, Corriu and co-
workers5 and McGlinchey and co-workers11 have shown
that such ligands are compatible with the presence of
Cr(CO)3 groups. Indeed, Manners recently reported a
compound in which a chromium atom was sandwiched
between two aryl groups bound to a single silicon (Ar-
SiR2-Ar).17
On the basis of the premise that the combination of
different metals could affect the properties of a com-
pound cooperatively, as has been seen with short
dimetal oligoalkynes,8 we chose to devise ligands that
(i) could readily be prepared as small molecules or
polymers, (ii) lend themselves to the selective binding
(8) (a) Weng, W.; Bartik, T.; Gladysz, J . A. Angew. Chem., Int. Ed.
Engl. 1994, 33, 2199. (b) Brady, M.; Weng, W.; Gladysz, J . A. J . Chem.
Soc., Chem. Commun. 1994, 2655. (c) Weng, W.; Ramsden, J . A.; Arif,
A. M.; Gladysz, J . A. J . Am. Chem. Soc. 1993, 115, 3824. (d) Weng,
W.; Bartik, T.; Brady, M.; Bartik, B.; Ramsden, J . A.; Arif, A. M.;
Gladysz, J . A. J . Am. Chem. Soc. 1995, 117, 11922. (e) Brady, M.; Weng,
W.; Zhou, Y.; Seyler, J . W.; Amoroso, A. J .; Arif, A. M.; Bohme, M.;
Frenking, G.; Gladysz, J . A. J . Am. Chem. Soc. 1997, 119, 775. (f)
Hradsky, A.; Bildstein, B.; Schuler, N.; Schottenberger, H.; J aitner,
P.; Ongania, K.-H.; Wurst, K.; Launay, J .-P. Organometallics 1997,
16, 392.
(9) Brook, M. A.; Ramacher, B.; Dallaire, C.; Gupta, H. K.; Ulbrich,
D.; Ruffolo, R. Inorg. Chim. Acta. 1996, 250, 49.
(10) Ruffolo, R.; Decken, A.; Girard, L.; Gupta, H. K.; Brook, M. A.;
McGlinchey, M. J . Organometallics 1994, 13, 4328.
(11) Malisza, K. L.; Chao, L. C. F.; Britten, J . F.; Sayer, B. G.;
J aouen, G.; Top, S.; Decken, A.; McGlinchey, M. J . Organometallics
1993, 12, 2462.
* To whom correspondence should be addressed. E-mail:
mabrook@mcmaster.ca. Phone: (905) 525-9140 ext. 23483. Fax: (905)
522-2509.
X Abstract published in Advance ACS Abstracts, October 15, 1997.
(1) Manners, I. Angew. Chem., Int. Ed. Engl. 1996, 35, 1602.
(2) (a) Manners, I. Adv. Mater. 1994, 6, 68. (b) Rulkens, R.; Lough,
A. J .; Manners, I. J . Am. Chem. Soc. 1994, 116, 797. (c) Nelson, J . M.;
Rengel, H.; Manners, I. J . Am. Chem. Soc. 1993, 115, 7035. (d) Foucher,
D. A.; Tang, B.-Z.; Manners, I. J . Am. Chem. Soc. 1992, 114, 6246.
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Losada, J . Organometallics 1995, 14, 2618.
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Chem., Int. Ed. Engl. 1995, 34, 569. (c) Bunz, U. H. W. Angew. Chem.,
Int. Ed. Engl. 1996, 35, 969. (d) Gleiter, R.; Stahr, H.; Nuber, B.
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Organometallics 1995, 14, 5362. (b) Cuadrado, I.; Mora´n, M.; Moya,
A.; Casado, C. M.; Barranco, M.; Alonso, B. Inorg. Chim. Acta 1996,
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S0276-7333(97)00298-7 CCC: $14.00 © 1997 American Chemical Society

Oligo(alkynylsilanes)
Organometallics, Vol. 16, No. 23, 1997 5049
Ch a r t 1
Sch em e 1
It is hoped that judiciously selected combinations of
organometallic moieties will lead to materials similar
to those noted above, but with tunable properties. We
report herein our model synthetic studies in this area.
much to the pioneering work of Seyferth,19 Marko´,20 and
their respective co-workers. Many other workers have
also contributed to this area.21 Following these prece-
dents, the hexacarbonyldicobalt complexes 7-11 (see
eqs 1-4 and Scheme 1) were prepared by stirring the
appropriate precursors 1-5, respectively, with Co2(CO)8
in freshly distilled tetrahydrofuran at room tempera-
ture. Beautiful deep red complexes were obtained in
excellent yield. Especially noteworthy are the silicone-
based compounds 10 and 11 (Mh w ) ca. 50 000), which,
unlike the other cobalt complexes, are fluids. Although
Co2(CO)8 will react with Si-H compounds, this reaction
did not accompany the conversion of 1 to 7.10 We ascribe
Resu lts a n d Discu ssion
The ligands from which we chose to make polymeric
materials are the silanes 1-6, as shown in Chart 1.18
These all contain two potential sites for transition-metal
coordination, namely the alkynyl and aryl groups.
Smaller molecules, such as Me3SiCtCSiMe2(CH2)3Si-
(H)Ph (1) and (Me3SiCtCSiMe2(CH2)3)2SiPh2 (2), were
used to establish the conditions necessary to selectively
attach a transition-metal fragment to one of the two
potential ligand binding sites. Subsequently, the condi-
tions were established whereby the second organome-
tallic moiety could be incorporated without decomplex-
ing the first.
(19) Seyferth, D.; White, D. L. J . Organomet. Chem. 1971, 32, 317.
(20) Pa´lyi, G.; Va´radi, G.; Marko´, L. In Stereochemistry of Organo-
metallic Compounds and Inorganic Compounds; Bernal, I., Ed.;
Elsevier: Amsterdam, 1986; Vol. 1, Chapter 5, pp 358-410.
(21) (a) For some selected examples, see: (a) Magnus, P.; Becker,
D. P. J . Chem. Soc., Chem Commun. 1985, 640. (b) Ruffolo, R.; Kainz,
S.; Gupta, H. K.; Brook, M. A.; McGlinchey, M. J . J . Organomet. Chem.,
in press. (c) Brook, M. A.; Ramacher, B.; Dallaire, C.; Gupta, H. K.;
Ulbrich, D.; Ruffolo, R. Inorg. Chim. Acta 1996, 250, 49. (d) Ruffolo,
R.; Decken, A.; Girard, L.; Gupta, H. K.; Brook, M. A.; McGlinchey,
M. J . Organometallics 1994, 13, 4328. (e) Corriu, R. J . P.; Douglas, W.
E.; Yang, Z. X. Polymer 1993, 34, 3535. (f) Rubin, Y.; Knobler, C. B.;
Diederich, F. J . Am. Chem. Soc. 1990, 112, 1607. (g) Pannell, K. H.;
Crawford, G. M. J . Coord. Chem. 1973, 2, 251.
Com p lexes P ossessin g a Sin gle Typ e of Or ga n o-
m eta llic Moiety. Coba lt. The preparation and uti-
lization of dicobalt complexes of alkynylsilanes owes
(18) Kuhnen, T.; Stradiotto, M.; Ruffolo, R.; Ulbrich, D.; McGlinchey,
M. J .; Brook, M. A. Organometallics 1997, 16, 5042.

5050 Organometallics, Vol. 16, No. 23, 1997
Kuhnen et al.
possesses only a single alkynyl unit but also contains
an Si-H linkage, led to unexpected results. When 1
was heated at reflux with Cr(CO)6 in di-n-butyl ether,
the product was initially assumed to be 14, analogous
to 12. The compound exhibited the expected number
of 1H and 13C NMR resonances, and the mass spectrum
and microanalytical data also were consistent with this
formulation (see Scheme 3). However, the purported
Si-H absorption at 7.77 ppm in the proton NMR
spectrum was considerably deshielded relative to its
normal resonance position. Moreover, the 2D 29Si-1H
NMR (HMBC) demonstrated unequivocally that this
proton was coupled to all three silicon atoms, eliminat-
ing 12 as the correct structure. We were alerted to the
possibility of an intramolecular hydrosilation (to give
15) when a search of the literature revealed that the
alkene proton in trisilylated ethenes is generally found
in the range δ 7.1-7.3.24 The particular absorption, at
δ 7.77 ppm, was further deshielded from these values
by approximately 0.5 ppm. To clarify this point, and to
establish the molecular connectivity definitively, an
X-ray crystal structure determination was undertaken.
Figure 2 depicts the molecule 15 and confirms the cyclic
nature of the product. It is evident that cis addition of
the Si-H moiety across the alkynyl linkage has oc-
curred. The X-ray data also provide a rationale for the
strongly deshielded character of the alkene proton at δ
7.77 ppm. Relevant crystallographic data are collected
in Tables 1 and 3.
(1)
(2)
(3)
The diamagnetic anisotropy of inorganic or organo-
metallic fragments, such as metal-metal triple bonds,25
ferrocenyl units,26 and metal carbonyl linkages,27 has
been the subject of numerous studies. In particular, the
CrsCtO linkage behaves analogously to the alkynyl
group in that protons lying close to the C∞ axis are
markedly shielded while those hydrogens more nearly
perpendicular to the MsCtO bond are strongly deshield-
ed. The incremental shift, σ, in parts per million, is
given by the formula σ ) øCrCO(1 - 3cos2 θ)/((3R3)4π),
where R is the distance from the proton to the center of
the CtO bond and θ is the angle made by R with the
CrsCtO axis.27 In the case at hand, the values of R
and θ were obtained from the X-ray crystal structure
of 15, and øCrCO was taken as -490 × 10-36 m3/
molecule.28 These structural data predict that the
ethene proton should be deshielded by 0.58 ppm.
Subsequent decomplexation of the bis-Cr(CO)3 complex
15 by photolysis in sunlight yielded the free ligand 16,
in which the ethene hydrogen now absorbed at ap-
proximately δ 7.3 ppm.
(4)
this to the steric encumbrance provided by the flanking
phenyl groups.22
Ch r om iu m . The incorporation of tricarbonylchro-
mium units into arylsilanes is well-established,5,11,23 and
the alkynylarylsilanes 2 and 6 react with chromium
hexacarbonyl to yield the chromium complexes 12 and
13, respectively (see Schemes 1 and 2). To complement
the usual analytical and spectroscopic data, 12 was also
characterized by X-ray crystallography. The molecular
structure appears in Figure 1, and the relevant crystal-
lographic data are collected in Tables 1 and 2. The
molecular geometry reveals no unusual features but
serves to identify the product unequivocally. However,
the conformation adopted, at least in the solid state,
leaves the alkynyl groups relatively unencumbered and
readily available for coordination to a dicobalt or dimo-
lybdenum fragment.
Initially, it was assumed that the hydrosilylation
catalyst in this reaction was the added chromium agent,
i.e. Cr(CO)6, or an aryl-Cr(CO)3 complex. However, it
was discovered that a purified sample of 1 left at room
temperature for a few months contained about 80% 16.
(24) (a) Kerst, C.; Rogers, C. W.; Ruffolo, R.; Leigh, W. J . J . Am.
Chem. Soc. 1997, 119, 466. (b) Ishikawa, M.; Sugisawa, H., Fuchikami,
T.; Kumada, M.; Yamabe, T.; Kawakami, H.; Fukui, K.; Ueki, Y.;
Shizuka, H. J . Am. Chem. Soc. 1982, 104, 2872. (c) Seyferth, D.;
Annarelli, D. C.; Vick, S. C. J . Organomet. Chem. 1984, 272, 123.
(25) McGlinchey, M. J . Inorg. Chem. 1980, 19, 1392.
(26) (a) Turbitt, T. D.; Watts, W. E. Tetrahedron 1972, 28, 1227. (b)
Mulay, L. N.; Fox, M. E. J . Chem. Phys. 1963, 38, 760.
(27) (a) McConnell, H. M. J . Chem. Phys. 1957, 27, 226. (b) Harris,
R. K. Nuclear Magnetic Resonance Spectroscopy; Pittmann: London,
England, 1983; p 193.
In contrast, attempts to perform the analogous com-
plexation reaction with the model compound 1, which
(22) Corriu, R. J . P.; Moreau, J . J . E.; Praet, H. Organometallics
1990, 9, 2086.
(23) (a) Uemura, M. Rev. Heteroat. Chem. 1994, 10, 251. (b) Solladie´-
Cavallo, A. Trends Org. Chem. 1990, 237. Uhlig, E. Organometallics
1993, 12, 4751.
(28) McGlinchey, M. J .; Burns, R. C.; Hofer, R.; Top, S.; J aouen, G.
Organometallics 1986, 5, 104.

Oligo(alkynylsilanes)
Organometallics, Vol. 16, No. 23, 1997 5051
Sch em e 2
either electrophilic or electron-rich dienes. The lack of
reactivity in these cases can be attributed to steric
hindrance of the alkyne provided by the flanking groups.
The bulk of these SiMe2R ligands in 1 can be seen from
the ball-and-stick representation of the structure cal-
culated using molecular mechanics (Figure 3). In
contrast, the proximity of functional groups in 1 and
the intramolecular nature of the hydrosilylation process
to give 15 or 16 presumably enhances the reactivity in
this particular case. The transition state leading to
hydrosilylation was modeled by constraining the Me3-
SiC‚‚‚HSiPh2 distance to 3 Å and minimizing the
structure. It can be appreciated from Figure 3 that,
while steric hindrance is still significant, one of the
flanking groups (SiMe2) has adopted a conformation
that minimizes the steric constraints allowing the
intramolecular hydrosilylation to proceed.
Mixed-Metal System s. Following a systematic evalu-
ation, the most efficient sequence for the preparation
of the mixed-metal systems proved to involve complex-
ation of the aryl system prior to introduction of transi-
tion metals to the alkynyl moieties. Thus, the mixed
molybdenum/chromium complex 19 was prepared by
stirring the chromium complex 12 in di-n-butyl ether
with Mo2Cp2(CO)4. Analogously, the mixed chromium/
cobalt compounds 20 and 21 (Schemes 2 and 4) were
made by stirring 12 and 13, respectively, with Co2(CO)8
in THF.
Single crystals suitable for X-ray crystallographic
analysis were obtained of the chromium/cobalt complex
20; relevant crystallographic data and the resulting
structure appear in Tables 1 and 4 and Figure 4,
respectively. While the organometallic fragments Co2-
(CO)6 and Cr(CO)3 respectively show very typical struc-
tures, the overall conformation of an individual molecule
looks rather awkward. An examination of the packing
diagram along the a axis, however, shows that associa-
tion of similar metal clusters, a type of self-assembly,
is apparently driving the packing in the crystal. One
can clearly observe repeating layers of cobalt-cobalt-
F igu r e 1. Molecular structure of 12 showing 30% prob-
ability ellipsoids.
Thus, in spite of purification of 1 by column chroma-
tography, it is concluded that residual platinum from
the initial preparation of 1 accounts for the hydrosilyl-
ation, both in the presence and absence of Cr(CO)6,
although thermal activation cannot be discounted. This
is in accord with the observed intramolecular cyclization
of a chromatographically purified sample of Ph2(H)-
Si(CH2)3SiMe2CtCSiMe2(CH2)3Si(H)Ph2 (17) to 18 over
a period of approximately 1 month. The structural
isomers 17 and 18 were readily differentiated by use of
a 2D 29Si-1H NMR (HMBC) experiment (eq 5).
The intramolecular hydrosilylation reaction of 1 was
somewhat unexpected. Previous experiments with the
related silylalkyne (Me3SiCtC)4Si9,29 showed it to be
completely inert to the normal conditions used for the
Pauson-Khand reaction,30 to electrophilic attack by acid
or nucleophilic attack by fluoride,9,31 to Vollhardt cy-
clotrimerization, or to Diels-Alder reactions32 with
(29) Dallaire, C.; Brook, M. A.; Bain, A. D.; Frampton, C. S.; Britten,
J . F. Can. J . Chem. 1993, 71, 1676.
(30) (a) Pauson, P. L.; Khand, I. U. Ann. N. Y. Acad. Sci. 1977, 295,
2. (b) Pauson, P. L. Tetrahedron 1985, 41, 5855. (c) Schore, N. E. Org.
React. 1991, 40, 1.
(32) (a) Sauer, J . Angew. Chem., Int. Ed. Engl. 1966, 5, 211. (b)
Sauer, J . Angew. Chem., Int. Ed. Engl. 1967, 6, 16. (c) Wollweber, H.
Diels-Alder Reactions. In Houben-Weyl Methoden der organische
Chemie, 4th ed.; Mu¨ller, E.; Ed.; Thieme: Stuttgart, Germany, 1970;
p 977.
(31) Dallaire, C.; Brook, M. A. Organometallics 1993, 12, 2332.

5052 Organometallics, Vol. 16, No. 23, 1997
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t Deta ils for 12, 15, a n d 20
Kuhnen et al.
12
15
20
empirical formula
mol wt
C38H52Cr2O6Si5
849.25
C28H32Cr2O6Si3
652.81
C50H52Co4Cr2O18Si5
1421.09
descripn
dimens, mm
temp, K
yellow prism
0.44 × 0.25 × 0.18
293(2)
yellow prism
0.50 × 0.25 × 0.12
300(2)
red plate
0.38 × 0.18 × 0.05
300(2)
wavelength, Å
cryst syst
space group
a, Å
b, Å
c, Å
0.710 73 (Mo KR)
monoclinic
P21/c
triclinic
P1h
monoclinic
C2/c
12.828(3)
13.526(3)
13.909(3)
92.29(3)
105.02(3)
100.22(3)
2284.7(8)
2
18.910(2)
10.533(2)
16.532(2)
90.000(0)
109.51(1)
90.000(0)
3103.7(6)
4
45.975(5)
12.936(2)
24.459(3)
90.000(0)
115.767(7)
90.000(0)
13100(3)
8
R, deg
â, deg
γ, deg
V, Å3
Z
calcd density, g/cm3
abs coeff, mm-1
F(000)
1.234
0.646
892
1.397
0.854
1352
1.441
1.462
5776
θ range for collecn, deg
transmissn min
transmissn max
index ranges
1.52-26.73
2.25-25.00
1.65-22.50
0.794
0.842
0.683
0.948
0.913
0.968
-16 e h e 16
-16 e k e 16
-14 e l e 17
18895
-22 e h e 21
-12 e k e 1
-1 e l e 19
6896
0 e h e 49
0 e k e 13
-26 e l e 23
8195
no. of rflns collected
no. of indep rflns
8680
5478
8073
R(int)
0.0185
0.0470
0.0587
refinement method
no. of data/restraints/params
goodness of fit on F2
final R indices (I > 2σ(I))a
full-matrix least squares on F2
5478/3/358
1.021
8680/0/461
1.032
8073/0/712
0.836
R1 ) 0.0380
wR2 ) 0.0993
R1 ) 0.0511
wR2 ) 0.1090
0.414
0.0580
0.1313
0.1013
0.1569
0.850
-0.524
0.0818
0.2107
0.1606
0.2667
1.111
R indices (all data)a
largest diff peak, e/Å3
largest diff hole, e/Å3
-0.335
-0.740
a
2
R1 ) ∑(||Fo| - |Fc||)/∑|Fo|. wR2 ) [∑[w(Fo - Fc2)2]/∑w[(Fo)2)2]]0.5
.
Ta ble 2. Selected Sa lien t Bon d Len gth s (Å) a n d
An gles (d eg) for 12
except for 2D experiments on the DRX 500, were recorded on
spinning samples. Peaks were referenced to a residual proton
signal of the solvent or to a 13C solvent signal.
In some of the 13C NMR spectra, it was not possible to
observe the carbonyl peaks.
Si(3)-C(29)
Si(3)-C(23)
C(35)-C(34)
1.853(2)
1.881(2)
1.198(4)
Cr(1)-C(46)
Cr(2)-C(47)
Si(4)-C(34)
1.802(3)
1.837(3)
1.837(3)
1H-Detected 29Si Mu ltip le-Bon d (HMBC) Cor r ela tion
E xp er im en t . The 29Si spectral width was 5531.0 Hz with
2048 data points, zero-filled to 4096. The 1H spectral width
was 5952.4 Hz with 256 time increments and 64 scans per
increment. A relaxation delay of 2 s between scans was used.
Values of J Si-H ) 224 Hz and J Si-H ) 6.7 Hz were used to
calculate ∆1 and ∆2 (∆1 ) 1/[2(1J Si-H)] and ∆2 ) 1/[2(2J Si-H)]).
Infrared spectra were obtained on a Bio-Rad FTS-40 spec-
trometer, using NaCl windows. Electron impact (EI) and
chemical ionization (CI, NH3) mass spectra were recorded at
70 eV with a source temperature of 200 °C on a VG analytical
ZAB-E mass spectrometer equipped with a VG 11-250 data
system. High-resolution mass spectra were determined in the
EI mode on the same instrument.
Si(4)-C(34)-C(35) 176.5(3)
C(16)-Si(3)-C(17) 114.38(12)
C(17)-Si(3)-C(23) 105.97(10)
chromium lying in the b-c plane (Figure 5). We intend
to examine the crystal packing in the related systems
19 and 21 to establish whether this is a general
phenomenon.33
Having established that such mixed-metal systems
may be readily prepared, we are in the process of
preparing higher molecular weight, silicone-based sys-
tems with the goal of establishing the conditions under
which the different organometallic fragments will act
cooperatively.
1
2
The molecular weights of the hydrophobic polymers were
analyzed using a Waters Gel Permeation Chromatograph
(GPC) equipped with a Waters 510 HPLC pump and a Waters
410 differential refractive index detector. Two J ordi mixed-
bed columns and one Waters 4E column in series were utilized
with 1,1,1-trichloroethane as solvent flowing at 1 mL/min.
Pretreatment of the HPLC grade 1,1,1-trichloroethane in-
volved filtration through a 400 µm Teflon filter. Narrow-
molecular-weight polystyrene and silicone standards from
Scientific Polymer Products Inc. were used for calibration of
the chromatographic system. While we recognize that neither
standard will give an accurate molecular weight value for
compounds 5 and 11, comparison of the retention volumes of
the standards and the known molecular weights of the starting
materials with those of the products allows us to estimate the
Exp er im en ta l Section
In str u m en ta tion . 1H NMR and 13C NMR spectra were
recorded using a Bruker AC-200 spectrometer (at 200.13 MHz
for 1H and 50.3 MHz for 13C) or on a Bruker DRX 500
spectrometer with an 11.74 T superconducting magnet,
equipped with a Bruker B-VT 2000 temperature controller and
a 5 mm multinuclear inverse probe equipped with three-axis
gradients. 1H, 29Si, and 13C NMR data were obtained at
500.13, 99.36, and 125.76 MHz, respectively. All spectra,
(33) For a recent discussion of organometallic crystal engineering,
refer to: Braga, D.; Grepioni, F. J . Chem. Soc., Chem. Commun. 1996,
571.

Oligo(alkynylsilanes)
Organometallics, Vol. 16, No. 23, 1997 5053
Sch em e 3
F igu r e 3. Structure of disilylalkynes 1a ,b (additional
hydrogens omitted for clarity): 1a , calculated using mo-
lecular mechanics (MM2); 1b, calculated using MM2 with
Me3SiC‚‚‚HSiPh2 constrained to 3 Å.
F igu r e 2. Molecular structure of 15 showing 30% prob-
ability ellipsoids.
Ta ble 3. Selected Sa lien t Bon d Len gth s (Å) a n d
An gles (d eg) for 15
single-crystal sample, which was mounted on a glass fiber.
Data were collected using a P4 Siemens diffractometer,
equipped with a Siemens SMART 1K charge-coupled device
(CCD) area detector (using the program SMART34 ) and a
rotating anode using graphite-monochromated Mo KR radia-
tion (λ ) 0.710 73 Å). The crystal-to-detector distance was
3.991 cm, and the data collection was carried out in 512 ×
512 pixel mode, utilizing 2 × 2 pixel binning. The initial unit
cell determination was carried out by scanning 4.5° in 15
frames over 3 different parts of reciprocal space (45 frames,
C(2)-C(7)
Si(8)-C(7)
Si(1)-C(17)
Si(1)-C(11)
1.344(7)
1.888(5)
1.886(5)
1.895(5)
Si(3)-C(4A)
Si(3)-C(2)
Si(1)-C(2)
1.883(14)
1.890(5)
1.880(4)
C(4A)-Si(3)-C(2)
C(5A)-C(4A)-Si(3)
Si(1)-C(2)-Si(3)
112.6(5)
121.2(10)
114.6(2)
C(7)-C(2)-Si(1)
C(7)-C(2)-Si(3)
116.9(3)
128.4(3)
number of iterative hydrosilylations which occurred. Data
manipulation was done using Waters Millenium Chromatog-
raphy Manager software.
Cr ysta l Str u ctu r e Deter m in a tion s. X-ray crystallo-
graphic data for 12 (Tables 1 and 2) were collected from a
(34) SMART, Release 4.05; Siemens Energy and Automation, Inc.,
Madison, WI 53719, 1996.

5054 Organometallics, Vol. 16, No. 23, 1997
Kuhnen et al.
Sch em e 4
Ta ble 4. Selected Sa lien t Bon d Len gth s (Å) a n d
An gles (d eg) for 20
Co(3)-C(34)
Co(3)-Co(4)
Co(4)-C(34)
1.997(12)
2.525(3)
2.007(13)
Si(3)-C(17)
Si(4)-C(34)
1.889(12)
1.880(14)
C(16)-Si(3)-C(23) 109.7(5) C(34)-C(35)-Si(5)
C(29)-Si(3)-C(23) 105.3(5) Si(5)-C(35)-Co(4)
C(29)-Si(3)-C(16) 112.5(5) C(34)-C(35)-Co(3)
142.6(13)
132.1(10)
72.1(11)
F igu r e 5. Crystal-packing diagram of 20 showing the
cobalt- and chromium-rich layers.
F igu r e 4. Molecular structure of 20 showing 30% prob-
ability ellipsoids.
atoms were included as fixed contributors at calculated posi-
tions and refined using a riding model with isotropic displace-
ment parameters equal to 1.2 times the equivalent isotropic
displacement parameter of their attached atom.
180 reflections total). The strong reflections were then chosen
and used in the determination of the unit cell. One complete
hemisphere of data was collected, to better than 0.8 Å
resolution. Upon completion of the data collection, the first
50 frames were re-collected in order to improve the decay
correction analysis. Processing was carried out by use of the
program SAINT,35 which applied Lorentz and polarization
corrections to three-dimensionally integrated diffraction spots.
The program SADABS36 was utilized for the scaling of dif-
fraction data, the application of a decay correction, and an
empirical absorption correction based on redundant reflections.
The structures were solved by using the direct methods
procedure in the Siemens SHELXTL program library37 and
refined by full-matrix least-squares methods with anisotropic
thermal parameters for all non-hydrogen atoms. All hydrogen
X-ray crystallographic data for 15 and 20 were collected
from single crystals, which were mounted on a glass fiber and
transferred to a P4 Siemens diffractometer, equipped with a
rotating anode and graphite-monochromated Mo KR radiation
(λ ) 0.710 73 Å). Three standard reflections, which were
measured after every 97 reflections, showed neither instru-
ment instability nor crystal decay. Data were corrected for
absorption using an empirical Ψ-scan method.38 The struc-
tures were solved by using the direct-methods procedure in
the Siemens SHELXTL program library37 and refined by full-
matrix least-squares methods with anisotropic thermal pa-
rameters for all non-hydrogen atoms. With the exception of
the vinylic and aromatic protons in 15, all hydrogen atoms
were included as fixed contributors at calculated positions.
Crystallographic data collection parameters for 15 and 20 are
summarized in Table 1.
(35) SAINT, Release 4.05; Siemens Energy and Automation, Inc.,
Madison, WI 53719, 1996.
(36) Sheldrick, G. M. SADABS (Siemens Area Detector Absorption
Corrections), 1996.
(37) Sheldrick, G. M. SHELXTL PC, Release 4.1; Siemens Crystal-
lographic Research Systems, Madison, WI 53719, 1994.
(38) Sheldrick, G. M. XPREP, Version 5.03; Siemens Crystal-
lographic Research Systems, Madison, WI 53719, 1994.

Oligo(alkynylsilanes)
Organometallics, Vol. 16, No. 23, 1997 5055
with cyclohexane/CH2Cl2 (90:10), 7 as a red waxy solid (0.52
g, 0.78 mmol; 85%). 1H NMR (CD2Cl2, 200.13 MHz): δ 7.48
(m, 10H, aromatic), 4.77 (m, 1H, Si-H), 1.75 (m, 2H, CH2CH2-
CH2), 1.21 (m, 2H, SiPh2CH2), 0.83 (m, 2H, SiMe2CH2), 0.21
(s, 6H, Si(CH3)2), 0.17 (s, 9H, Si(CH3)3). 13C NMR (CD2Cl2,
75.03 MHz): δ 134.4, 130.2, 128.2 (aromatic), 21.2 (CH2CH2-
CH2), 20.3 (SiPh2CH2), 18.4 (SiMe2CH2), 1.1 (Si(CH3)2), -0.6
(Si(CH3)3). IR (neat, cm-1): νCO 2018 (sh), 2045 (m), 2083 (sh).
(Me3SiCtCSiMe2CH 2CH 2CH 2)2SiP h 2[Co2(CO)6]2 (8).
Co2(CO)8 (0.60 g, 1.75 mmol) and (Me3SiCtCSiMe2CH2CH2-
CH2)2SiPh2 (2; 1.00 g, 1.74 mmol) yielded the dark red waxy
solid 8 (1.71 g, 1.49 mmol; 85%). 1H NMR (CD2Cl2, 200.13
MHz): δ 7.40 (m, 10H, aromatic), 1.47 (m, 4H, CH2CH2CH2),
1.22 (m, 4H, SiMe2CH2), 0.72 (m, 4H, SiPh2CH2), 0.13 (s, 12H,
Si(CH3)2), 0.09 (s, 18H, Si(CH3)3). 13C NMR (CD2Cl2, 75.03
MHz): δ 135.9, 135.2, 129.4, 128.1 (aromatic), 21.0 (CH2CH2-
CH2), 19.0 (SiPh2CH2), 18.7 (SiMe2CH2), -0.5 (Si(CH3)3), -4.8
(Si(CH3)2). 29Si NMR (CH2Cl2, 59.6 MHz): δ 0.5 (SiPh2), -18.5
(Si(CH3)3), -19.6 (Si(CH3)2). IR (neat, cm-1): νCO 2017 (m),
2045 (sh), 2083 (sh).
CH2dCHCH2SiMe2CtCSiMe2CH2CHdCH2[Co2(CO)6] (9).
Co2(CO)8 (1.71 g, 5.00 mmol) and CH2dCHCH2SiMe2CtCSiMe2-
CH2CHdCH2 (3; 1.11 g, 5.00 mmol) after chromatography with
toluene/acetone (80:20) gave the desired compound 9 as a red
waxy solid (2.21 g, 4.35 mmol; 87%).21b 1H NMR (CD2Cl2,
200.13 MHz): δ 5.78 (m, 2H, CH2dCHCH2), 4.95 (m, 4H,
CH2dCHCH2), 1.63 (m, 4H, CH2dCHCH2), 0.29 (s, 12H, Si-
(CH3)2). 13C NMR (CD2Cl2, 75.03 MHz): δ 201.6 (CtO), 133.6
(CH2dCHCH2), 114.6 (CH2dCHCH2), 25.2 (CH2dCHCH2),
-1.0 (Si(CH3)2). 29Si NMR (CH2Cl2, 59.6 MHz): δ -0.8. IR
(neat, cm-1): νCO 2018 (sh), 2046 (m), 2085 (sh). Mass
spectrum (DEI, m/ z (%)): 467 (15) ([M - C3H5]+), 424 (60)
([M - 3(CO)]+), 396 (50) ([M - 4(CO)]+), 368 (45) ([M -
(5)
For 15, the final refined structure was based on a disordered
model in which the six-membered ring could exist in one of
two nonplanar conformations. On the basis of the observed
thermal displacement ellipsoids, it was assumed that only the
positions of the three methylene carbon atoms of the ring were
significantly affected by this disorder. The occupancy of the
two conformations was refined as a free variable (the final ratio
of approximately 56:44), and then hydrogen atoms for each
unique component of the disorder were placed in calculated
positions and refined on the basis of the carbon atom to which
they were attached.
Molecu la r Mech a n ics Ca lcu la tion s. The structure of 15
was calculated using Hyperchem (Waterloo, Canada) with the
MM2 parameter set on an IBM-compatible computer (Pentium
processor under Windows 95). The structure in Figure 3,
designed to model the approach to the transition state in the
hydrosilylation reaction leading to the cyclic structure, was
calculated using a fixed distance for Me3SiC‚‚‚HSiPh2 of 3 Å.
Ma ter ia ls. Tetrahydrofuran (Caledon) and di-n-butyl ether
(Aldrich) were distilled from potassium/benzophenone. CH2-
Cl2 (Caledon) was distilled prior to use from P4O10. Methanol
(Caledon) was distilled from Mg. Cyclohexane (Caledon),
hexane (Caledon), and toluene (Caledon) were distilled prior
to use. Only distilled water was used.
Co2(CO)8, Mo2Cp2(CO)6, and Cr(CO)6 were obtained from
Strem and were used as supplied without further purification.
All experiments were carried out under an atmosphere of
dry nitrogen, using standard Schlenk techniques. Solvents
were dried according to standard procedures. For all hydrosi-
lylations, 1 mol % of either Wilkinson’s ((Ph3P)3RhCl, Aldrich)
or Karstedt’s catalyst (Pt2(H2CdCHSiMe2OSiMe2CHdCH2)n,
Gelest) was used. Unless otherwise specified, compounds were
purified using flash chromatography. The eluents are provided
in each experimental description.
5(CO)]+), 340 (100) ([M
18H22Co2O6Si2: C, 42.26; H, 3.69. Found: C, 42.53; H, 4.50.
(Me3SiCtCSiMe2CH2CH2CH2SiMe2)2O[Co2(CO)6]2 (10).
-
6(CO)]+). Anal. Calcd for
C
Co2(CO)8 (1.10 g, 3.22 mmol) and (Me3SiCtCSiMe2CH2CH2-
CH2SiMe2)2O (4; 0.81 g, 1.54 mmol) gave, after chromatogra-
phy with hexanes, the desired compound (10 as a red-brown
oil (1.13 g, 1.03 mmol; 67%). 1H NMR (CD2Cl2, 200.13 MHz):
δ 1.44 (m, 4H, CH2CH2CH2), 0.81 (m, 4H, CH2Si(CH3)2O), 0.61
(m, 4H, Si(CH3)2CH2), 0.30 (s, 18H, Si(CH3)3), 0.27 (s, 12H,
Si(CH3)2), 0.03 (s, 12H, Si(CH3)2). 13C NMR (CD2Cl2, 75.03
MHz): δ 200.9 (CtO), 92.9, 92.0 (cluster carbons), 23.1
(CH2CH2CH2), 22.8 (CH2Si(CH3)2O), 18.0 (Si(CH3)2CH2), 1.1,
0.5, -0.6 (Si(CH3)’s). 29Si NMR (CH2Cl2, 59.6 MHz): δ 0.7 (Si-
(CH3)2), 0.5 (Si(CH3)3), -6.4 (Si(CH3)2O). IR (neat, cm-1): νCO
2084 (sh), 2046 (sh), 2020 (sh). Mass spectrum (DEI, m/ z
(%)): 644 (95), ([M - (C12O12Co2)]+), 585 (100) (M-(C12O12
-
Co3)]+).
-(Me2Si(CH2)3Me2SiCtCSiMe2(CH2)3(SiMe2O)nSiMe2O)m--
[Co2(CO)6]m (11). Co2(CO)8 (0.60 g, 1.75 mmol) and -Me2-
SiCtCSiMe2(CH2CHCH2)(SiMe2O)nSiMe2OSiMe2)m- (1.0 g,
Mh w ) 140 000, Mh w/Mh n ) 2.06) after filtration though 25 g of
silica gel afforded the red, highly viscous oil 11 (1.1 g). 1H
NMR (CDCl3, 200.13 MHz): δ 0.06 (broad, Si(CH3)’s). 13C
NMR (CDCl3, 50.3 MHz): δ 1.0 (Si(CH3)’s). IR (neat, cm-1):
νCO 2087 (m), 2047 (m), 2023 (sh). Mh w ) 155 000; Mh w/Mh n
2.51.
)
Liga n d s 1-6. The preparation and characterization of
these compounds has been discussed previously.18
Gen er a l P r oced u r e for th e P r ep a r a tion of Ch r om iu m
Ar yl Com p lexes. A 250 mL one-neck round-bottomed flask
was charged with Cr(CO)6, the arylsilane, and di-n-butyl ether
(50 mL). After the mixture had stirred for 72 h at reflux, the
solvent was removed by vacuum distillation. The residue was
subjected to flash chromatography on silica gel. Elution with
a nonpolar solvent gave the desired compound.
(Me3SiCtCSiMe2CH2CH2CH2)2SiP h 2[Cr (CO)3]2 (12). A
mixture of Cr(CO)6 (0.76 g, 3.45 mmol), (Me3SiCtCSiMe2CH2-
CH2CH2)2SiPh2 (2; 0.99 g, 1.72 mmol), and butyl ether was
reacted as described above. Elution of the residue on silica
with CH2Cl2 gave the crude desired compound, 12. Further
purification with methanol as recrystallization solvent yielded
Gen er a l P r oced u r e for th e P r ep a r a tion of Hexa ca r -
bon yld icoba lt Der iva tives. Co2(CO)8 (1 equiv, 0.4-1.7 g,
ca. 1-5 mmol) was dissolved in THF (30 mL), and a solution
of the alkyne (1 equiv) in THF (10 mL) was added dropwise
over a period of 30 min at 25 °C. The reaction mixture was
stirred overnight at room temperature. The solvent was
removed under reduced pressure. The mixture was then
subjected to flash chromatography on silica gel using elution
with nonpolar solvent mixtures.
Me3SiCtCSiMe2CH 2CH 2CH 2SiP h 2H [Co2(CO)6]
(7).
Co2(CO)8 (0.39 g, 1.14 mmol) and (Me3SiCtCSiMe2CH2CH2-
CH2SiPh2H) (1; 0.35 g, 0.92 mmol) gave, after chromatography

5056 Organometallics, Vol. 16, No. 23, 1997
Kuhnen et al.
pure 12 as bright yellow crystals (mp 86 °C, 0.99 g, 1.17 mmol,
H P h 2Si(CH 2CH 2CH 2)SiMe 2CtCSiMe 2(CH 2CH 2CH 2)-
SiP h 2H (17). To a mixture of diphenylsilane (4.14 g, 0.0225
mol) and (H2CdCHCH2)Me2SiCtCSiMe2(CH2CHdCH2) (2.5 g,
0.012 mol)18 at -15 °C was added Karstedt’s catalyst. After
1.5 h, the mixture was warmed to ambient temperature with
stirring for an additional 18 h. The crude mixture was then
subjected to flash chromatography on silica gel. Elution with
pentane/CH2Cl2 (5:1) gave the desired compound 17 as a clear
oil (6.6 g, 0.011 mol, 98%). 1H NMR (CDCl3, 200.13 MHz): δ
7.41 (m, 20H, aromatic), 4.90 (t, 2H, J ) 3.6 Hz, Si-H), 1.65
(m, 4H, CH2CH2CH2), 1.27 (m, 4H, SiPh2CH2), 0.74 (m, 4H,
SiMe2CH2), 0.09 (s, 12H, Si(CH3)2). 13C NMR (CDCl3, 50.03
MHz): δ 135.8, 135.4, 135.1, 134.5 (aromatic), 113.8 (CtC),
20.9, 20.0, 16.1 (CH2CH2CH2), -1.7 (Si(CH3)2). 29Si NMR (CH2-
Cl2, 59.6 MHz): δ -10.7 (PhSi), -15.0 (Si(CH3)2). IR (neat):
3
68%). 1H NMR (CD2Cl2, 200.13 MHz): δ 5.65 (t, 2H, J H-H
)
3
6.3 Hz, para), 5.49 (d, 4H, J H-H ) 6.1 Hz, ortho), 5.21 (m,
4H, meta), 1.66 (m, 4H, CH2CH2CH2), 1.22 (m, 4H, SiPh2CH2),
0.80 (m, 4H, SiMe2CH2), 0.15 (s, 12H, Si(CH3)2), 0.14 (s, 18H,
Si(CH3)3). 13C NMR (CD2Cl2, 75.03 MHz): δ 227.2 (CtO),
100.0, 96.2, 95.4, 90.2 (aromatic), 20.7 (CH2CH2CH2), 18.2
(SiPh2CH2), 15.5 (SiMe2CH2), -0.6 (Si(CH3)2), -2.2 (Si(CH3)3).
29Si NMR (CH2Cl2, 59.6 MHz): δ -4.4, -18.7, -19.7. IR (neat,
cm-1): νCO 1989 (sh), 1892 (sh). Anal. Calcd for C38H52Cr2O6-
Si5: C, 53.76; H, 6.18. Found: C, 53.37; H, 5.93. For
crystallographic data refer to Tables 1 and 2.
(Me3SiCtCSiMe2CH2CH2CH2SiMe2)2P h [Cr (CO)3] (13).
A mixture of Cr(CO)6 (0.78 g, 3.55 mmol), (Me3SiCtCSiMe2-
CH2CH2CH2SiMe2)2Ph (6; 1.56 g, 2.66 mmol), and butyl ether
were reacted as described above. Elution of the residue with
cyclohexane/CH2Cl2 (6:1) on silica gave the desired compound
13 as a yellow solid (mp 95 °C, 1.31 g, 1.81 mmol. 68%). 1H
NMR (CD2Cl2, 200.13 MHz): δ 5.34 (s, 4H, aromatic), 1.52 (m,
4H, CH2CH2CH2), 0.88 (m, 4H, Si(CH3)2Ph), 0.67 (m, 4H,
SiMe2CH2), 0.31 (s, 12H, Si(CH3)2), 0.15 (s, 12H, Si(CH3)2), 0.13
(s, 18H, Si(CH3)3). 13C NMR (CD2Cl2, 75.03 MHz): δ 225.5
(CtO), 115.0, 113.5 (CtC), 102.4, 98.3 (aromatic), 20.8
(CH2CH2CH2), 20.1 (Si(CH3)2Ph), 18.8 (SiMe2CH2), 0.2 (Si-
(CH3)3), -1.4 (Si(CH3)2), -3.2 (Si(CH3)2). 29Si NMR (CH2Cl2,
59.6 MHz): δ 0.4, -18.4, -19.7. IR (neat, cm-1): νCO 1966
(sh), 1893 (m). Mass spectrum (DEI, m/ z (%)): 722 (20) ([M]+),
638 (100) ([M - 3(CO)]+), 331 (10) ([C18H31Si3]+), 255 (50)
([C12H27Si3]+). Anal. Calcd for C33H58CrO6Si6: C, 54.83; H,
8.09. Found: C, 54.62; H, 8.22.
νSi-H 2116 cm-1
. Mass spectrum (DEI, m/ z (%)): 365 (30)
([C21H29Si3]+), 283 (55) ([C17H23Si2]+), 183 (100) ([C12H11Si]+).
Mass spectrum (CI, NH3, m/z (%)): 608 (10) ([M + 18]+), 366
(100) ([C21H29Si3 + 1]+). Anal. Calcd for C36H46Si4: C, 73.19;
H, 7.85. Found: C, 73.40; H, 8.10.
(H P h 2SiCH 2CH 2CH 2SiMe2H CdCSiMe2CH 2CH 2CH 2Si-
P h 2) (18). Spectroscopic studies of a sample of 17 (purified
and characterized 1 month earlier) demonstrated that 17 had
undergone a single intramolecular hydrosilylation to give 18,
in nearly quantitative yield. The cyclized product 18 was
unambiguously characterized by use of HMBC multidimen-
sional NMR (HMBC 29Si-1H 2D NMR, HSQC 13C-1H 2D
NMR, HMBC 13C-1H 2D NMR, 1H-1H COSY). 1H NMR
(CDCl3, 500.13 MHz): δ 7.90 (m, 10H, HPh2Si), 7.74 (m, 10H,
SiPh2), 7.72 (s, 1H, CdCH), 5.32 (s, 1H, SiH), 2.35 (m, 2H,
CH2CH2CH2), 1.96 (m, 2H, HPh2SiCH2CH2CH2), 1.76 (m, 2H,
Si(CH3)2CH2CH2CH2), 1.63 (m, 2H, HPh2SiCH2CH2CH2), 1.22
(m, 2H, HPh2SiCH2CH2CH2), 1.19 (m, 2H, Si(CH3)2CH2-
CH2CH2), 0.53 (s, 12H, Si(CH3)2). 13C NMR (CDCl3, 125.03
MHz): δ 168.5 (CdCH), 163.6 (CdCH), 135.9, 135.4, 135.1,
134.6 (Ph2SiH), 129.4, 129.0, 127.9, 127.6 (Ph2Si), 21.0 (HPh2-
SiCH2CH2CH2), 19.2 (Si(CH3)2CH2CH2CH2), 19.1 (HPh2-
SiCH2CH2CH2), 18.4 (CH2CH2CH2), 16.6 (HPh2SiCH2CH2CH2),
15.0 (Si(CH3)2CH2CH2CH2), 0.1 (Si(CH3)2), -1.2 (HPh2SiCH2-
CH2CH2Si(CH3)2). 29Si NMR (CH2Cl2, 99.36 MHz): δ -9.8
(Si(CH3)2), -12.1 (HPh2SiCH2CH2CH2Si(CH3)2), -16.3 (HPh2Si),
Me3SiCHCSiMe2CH2CH2CH2SiP h 2[Cr (CO)3]2 (15).
A
mixture of Cr(CO)6 (2.33 g, 10.6 mmol), Me3SiCtCSiMe2CH2-
CH2CH2SiPh2H (1; 1.81 g, 4.77 mmol), and butyl ether were
reacted as described above. Removal of volatile organics gave
a yellow solid which was recrystallized from methanol to give
15 (mp 175 °C, 2.30 g, 3.53 mmol; 74%). 1H NMR (CD2Cl2,
3
500.13 MHz): δ 7.77 (s, 1H, CdCH), 5.66 (t, 2H, J H-H ) 6.4
3
Hz, para), 5.51 (d, 4H, J H-H ) 6.1 Hz, ortho), 5.18 (m, 4H,
meta), 2.02 (m, 2H, CH2CH2CH2), 1.35 (m, 2H, SiPh2CH2), 0.86
(m, 2H, SiMe2CH2), 0.29 (s, 6H, Si(CH3)2), 0.22 (s, 9H,
Si(CH3)3). 13C NMR (CD2Cl2, 125.03 MHz): δ 226.1 (CtO),
172.9 (CdCH), 151.2 (CdCH), 101.6, 101.2, 97.1, 90.5 (aro-
matic), 18.4 (CH2CH2CH2), 18.0 (SiPh2CH2), 15.6 (SiMe2CH2),
0.3 (Si(CH3)2 and Si(CH3)3). 29Si NMR (CH2Cl2, 99.3 MHz): δ
-18.5 (Si(CH3)2), -19.8 (Si(CH3)3), -24.1 (SiPh2). IR (neat,
cm-1): νCO 1957 (m), 1882 (m), 1867 (sh). Mass spectrum (CI,
m/ z (%)): 652 (10) ([M]+), 568 (40) ([M - CO]+), 512 (15) ([M
- 5(CO)]+), 484 (100) ([M - 6(CO)]+). Anal. Calcd for
-19.8 (SiPh2). IR (neat): νSi-H 2116 cm-1
. Mass spectrum
(DEI, m/ z (%)): 590 (10) ([M]+), 575 (15) ([M - CH3]+), 513
(25) ([M - Ph]+), 365 (100) ([C25H29Si3]+). Mass spectrum (high
12
resolution, (DEI)): calculated msas for
C
H46Si4 ([M]+),
36
590.2677 amu; observed, 590.2665 amu. Anal. Calcd for
36H46Si4: C, 73.19; H, 7.85. Found: C, 73.14; H, 8.12.
P r ep a r a t ion of Mixed -Met a l Com p ou n d s.
C
(Me 3S iC tC S iMe 2C H 2C H 2C H 2)2S iP h 2[C r (C O )3]2[Mo 2-
(CO)4Cp 2]2 (19). A 250 mL one-necked round-bottomed flask
was charged with Mo2Cp2(CO)6 (0.98 g, 2.00 mmol) and di-n-
butyl ether (50 mL). The mixture was stirred for 24 h at reflux
to generate Mo2Cp2(CO)4.39 After cooling to room temperature,
a solution of 12 (0.77 g, 0.91 mmol) in CH2Cl2 (10 mL) was
added dropwise and the reaction mixture was stirred for 12
h. The solvent was removed by vacuum distillation and the
residue subjected to flash chromatography on silica gel.
Elution with cyclohexane/CH2Cl2 (9:1) gave the desired com-
pound 19 as a red solid (50 °C, 1.10 g, 0.64 mmol; 70%). 1H
NMR (CD2Cl2, 200.13 MHz): δ 5.40 (m, 10H, aromatic), 5.23
(s, 20H, Cp H’s), 1.64 (m, 4H, CH2CH2CH2), 1.23 (m, 4H,
SiPh2CH2), 0.82 (m, 4H, SiMe2CH2), 0.26 (s, 12H, Si(CH3)2),
0.15 (s, 18H, Si(CH3)3). 13C NMR (CD2Cl2, 75.03 MHz): δ
100.6, 96.8, 95.0, 90.9 (aromatic), 89.0 (Cp C’s), 21.2 (CH2CH2-
CH2), 18.7 (SiPh2CH2), 16.2 (SiMe2CH2), 0.1 (Si(CH3)3), -1.7
(Si(CH3)2). 29Si NMR (CH2Cl2, 59.6 MHz): δ 6.3, -18.7, -19.6.
IR (neat, cm-1): νCO 1970 (sh), 1893 (m).
C
28H32Cr2O6Si3: C, 51.52; H, 4.94. Found: C, 50.92; H, 4.51.
For crystallographic data, refer to Tables 1 and 3.
Me3SiHCdCSiMe2CH2CH2CH2SiP h 2 (16). To a 25 mL
vial charged with 15 (0.61 g, 0.94 mmol) was added a 1:1
mixture of hexane and CH2Cl2 (5 mL). After exposure to direct
light for approximately 2 weeks, the crude mixture was
subjected to flash chromatography on silica gel. Elution with
CH2Cl2/hexane (50:50) gave the desired compound 16 as a clear
colorless solid (0.31 g, 0.82 mmol; 88%). 1H NMR (CD2Cl2,
200.13 MHz): δ 7.39 (m, 11H, aromatic and Si-H), 1.85 (m,
2H, CH2CH2CH2), 1.26 (m, 2H, SiPh2CH2), 0.72 (m, 2H,
SiMe2CH2), 0.14 (s, 6H, Si(CH3)2), 0.07 (s, 9H, Si(CH3)3). 13C
NMR (CD2Cl2, 75.03 MHz): δ 169.3 (CdCH), 163.0 (CdCH),
136.0, 135.5, 129.2, 127.6 (aromatic), 19.3 (CH2CH2CH2), 18.4
(SiPh2CH2), 15.1 (SiMe2CH2), 0.5 (Si(CH3)3), -0.2 (Si(CH3)2.
29Si NMR (CH2Cl2, 59.6 MHz): δ -8.3, -10.6, -11.5. IR (neat,
cm-1): ν 2954 (sh), 2898 (m), 2854 (m), 1427 (w). Mass
spectrum (DEI, m/ z (%)): 380 (5) ([M]+), 365 (10) ([M - CH3]+),
303 (100) ([M - C6H5]+), 198 (22) ([M - Si(C12H10Si]+), 73 (76)
For the following two compounds, the general method for
the preparation of cobalt complexes was followed (see above).
([Si(CH3)3]+). Mass spectrum (high resolution, (DEI)): calcu-
12
lated mass for
C
H32Si3 ([M]+), 380.1812 amu; observed,
16
380.1808 amu. Anal. Calcd for C22H32Si3: C, 69.44; H, 8.48.
Found: C, 69.39; H, 8.83.
(39) Curtis, M. D.; Fotinos, N. A.; Messerle, L.; Sattelberger, A. P.
Inorg. Chem. 1983, 22, 1559.

Oligo(alkynylsilanes)
Organometallics, Vol. 16, No. 23, 1997 5057
(Me 3SiCtCSiMe 2CH 2CH 2CH 2)2SiP h 2[Cr (CO)3]2[Co2-
(CO)6]2 (20). Co2(CO)8 (0.81 g, 2.37 mmol) and 12 (1.00 g,
1.18 mmol) were reacted overnight at ambient temperature.
Removal of volatile organics yielded a red solid, which was
recrystallized from hexane to give dark red crystals of 20,
(aromatic), 93.9, 92.8 (cluster carbons), 22.5 (CH2CH2CH2),
20.6 (SiPh2CH2), 19.0 (SiMe2CH2), 1.3 (Si(CH3)3), 0.5 (Si(CH3)2),
-3.4 (Si(CH3)2). 29Si NMR (CH2Cl2, 59.6 MHz) δ 0.4 (C6H4-
SiMe3), -18.4 (Me2Si), -19.7 (SiMe3). IR (neat, cm-1): 2084
(sh), 2047 (sh), 2020 (m), 1965 (sh), 1893 (m).
suitable for X-ray diffraction (mp 114 °C, 0.98 g, 0.69 mmol;
3
58%). 1H NMR (CD2Cl2, 200.13 MHz): δ 5.66 (t, 2H, J H-H
)
Ack n ow led gm en t. We thank the Natural Sciences
and Engineering Research Council of Canada for the
financial support of this research. The support of T.K.
and D.U. by the Deutsche Akademische Austauschdi-
enst through a McMaster University: Universita¨t Du-
isburg Exchange Scholarship is greatly appreciated. We
acknowledge with gratitude the assistance of Bryan
Davies and Sabine Kainz (Universita¨t Duisburg), Dr.
Suzie Rigby (McMaster University), Dr. Richard Smith
(McMaster Regional Center for Mass Spectrometry), and
Dr. J ames F. Britten (X-ray crystallographic advice).
3
6.3 Hz, para), 5.48 (d, 4H, J H-H ) 6.1 Hz, ortho), 5.22 (m,
4H, meta), 1.69 (m, 4H, CH2CH2CH2), 1.23 (m, 4H, SiPh2CH2),
0.97 (m, 4H, SiMe2CH2), 0.32 (s, 12H, Si(CH3)2), 0.30 (s, 18H,
Si(CH3)3). 13C NMR (CD2Cl2, 75.03 MHz): δ 225.5 (Cr-CO),
200.1 (Co-CO), 99.9, 96.3, 94.3, 90.3 (aromatic), 22.2 (CH2CH2-
CH2), 18.4 (SiPh2CH2), 15.8 (SiMe2CH2), 0.6 (Si(CH3)2), -1.2
(Si(CH3)3). 29Si NMR (CH2Cl2, 59.6 MHz): δ 0.6 (Si(CH3)’s),
0.4 (SiPh2). IR (neat, cm-1): νCO 2084 (sh), 2044 (sh), 2014
(m), 1970 (m), 1895 (sh). Anal. Calcd for C50H52Co4Cr2O18
-
Si5: C, 42.26; H, 3.96. Found: C, 41.89; H, 3.45. For
crystallographic data, refer to Tables 1 and 4.
(Me3SiCtCSiMe2CH2CH2CH2SiMe2)2C6H4[Cr (CO)3][Co2-
(CO)6]2 (21). Co2(CO)8 (0.94 g, 2.75 mmol) and 13 (0.94 g,
1.30 mmol) were reacted overnight at ambient temperature.
Elution with hexane/CH2Cl2 (7:1) gave the desired compound
21 as a red oil (1.50 g, 1.16 mmol, 89%). 1H NMR (CDCl3,
200.13 MHz): δ 5.32 (s, 4H, aromatic), 1.53 (m, 4H, CH2CH2-
CH2), 0.90 (m, 8H, CH2CH2CH2), 0.34 (s, 12H, Si(CH3)2), 0.32
(s, 18H, Si(CH3)3), 0.28 (s, 12H, Si(CH3)2). 13C NMR (CDCl3,
75.03 MHz): δ 225.4 (CrsCtO), 201.6 (CosCtO), 102.1, 100.3
Su p p or tin g In for m a tion Ava ila ble: Tables of thermal
parameters, bond lengths, bond angles, and complete atomic
coordinates for compounds 12, 15, and 20 and figures giving
1H NMR and 13C NMR spectra for compounds 7, 8, 10, 11, 19,
and 21 (34 pages). Ordering information is given on any
current masthead page.
OM970298A