Preparation of hexacarbonyldicobalt-complexed 1,3-dioxa-2-silacycloheptynes

Article abstract of DOI:10.1021/om980589z

The reaction between 2-butyne-1,4-diol-hexacarbonyldicobalt and a series of dichlorodi-alkylsilanes (R = Me, Et, CH=CH₂, and Ph) in the presence of triethylamine results in the formation of the corresponding cobalt-complexed 1,3-dioxa-2-silacycloheptynes, 3-7, as the major products. Complexed silacyclononynes, 8 and 9, and a spirocyclic analogue 10, have also been prepared and characterized. The solid-state structures of 3 and 10 have been determined by X-ray diffraction studies. ? 1998 American Chemical Society.

Full text of DOI:10.1021/om980589z

5342
Organometallics 1998, 17, 5342-5346
P r ep a r a tion of Hexa ca r bon yld icoba lt-Com p lexed
1,3-Dioxa -2-sila cycloh ep tyn es
Michael A. Brook,* J o¨rg Urschey, and Mark Stradiotto
Department of Chemistry, McMaster University, 1280 Main Street West,
Hamilton, Ontario, Canada L8S 4M1
Received J uly 13, 1998
The reaction between 2-butyne-1,4-diol-hexacarbonyldicobalt and a series of dichlorodi-
alkylsilanes (R ) Me, Et, CHdCH2, and Ph) in the presence of triethylamine results in the
formation of the corresponding cobalt-complexed 1,3-dioxa-2-silacycloheptynes, 3-7, as the
major products. Complexed silacyclononynes, 8 and 9, and a spirocyclic analogue 10, have
also been prepared and characterized. The solid-state structures of 3 and 10 have been
determined by X-ray diffraction studies.
In tr od u ction
which has been exploited both in the protection of
alkynes4 and as a means of favorably effecting geometric
distortions in these moieties.5 Extending this method-
ology to the formation of metal-complexed silacy-
cloalkynes from coordinated diols and dichlorodialkyl-
silanes represents an attractive route to a variety of
organometallic rings comprising silicon and cobalt.
Moreover, oxidative decomplexation of the metal frag-
ment in these molecules would provide an efficient
synthetic pathway to an interesting class of heteroatom-
substituted cycloalkynes.
Cragg et al. previously reported that the use of alkyne
complexation to facilitate ring formation, in the syn-
thesis of cobalt-complexed 1,3-dioxa-2-silacycloheptynes
1, leads rather to the generation of dimeric 14-
membered ring species, analogous to 2 in Scheme 1.6
The potential utility of compounds such as 1, and the
hope that we could develop synthetic routes to favor the
formation of 1, prompted us to reexamine their work.
Herein we report the synthesis and characterization of
a series of cobalt-complexed 1,3-dioxa-2-silacyclohep-
tynes.
The preparation of polymers that contain pendant
and/or backbone transition-metal fragments has re-
cently received much attention, since these materials
often possess unique physical and chemical properties.1
Recently we reported the preparation of novel transi-
tion-metal-functionalized alkynylsilane-based oligomers
and polymers, which were efficiently assembled in an
iterative manner via hydrosilylation.2 The molecular
weights that could be achieved using this approach were
limited by the degree to which the stoichiometric ratio
of the difunctional starting materials could be matched.
In an attempt to develop alternative routes to such
materials, and with the specific goal of preparing higher
molecular weight polymers, we sought to prepare mono-
meric ring systems that could be subjected to traditional
ring-opening polymerization techniques.
The facile reaction between octacarbonyldicobalt and
alkynes, yielding pseudo-tetrahedral dimetallic clusters,
is a well-defined facet of organometallic chemistry,3
* Corresponding author. Fax: (905) 522-2509. Phone: (905) 525-
9140 ext. 23483. E-mail: mabrook@mcmaster.ca.
Resu lts a n d Discu ssion
(1) (a) Manners, I. Angew. Chem., Int. Ed. Engl. 1996, 35, 1602. (b)
Pittman, C. U.; Carraher, C. E.; Zeldin, M.; Sheats, J . E.; Culbertson,
B. M., Eds. Metal-Containing Polymeric Materials; Plenum Press: New
York, 1996. (c) Manners, I. Adv. Mater. 1994, 6, 68. (d) Rulkens, R.;
Lough, A. J .; Manners, I. J . Am. Chem. Soc. 1994, 116, 797. (e) Nelson,
J . M.; Rengel, H.; Manners, I. J . Am. Chem. Soc. 1993, 115, 7035. (f)
Foucher, D. A.; Tang, B.-Z.; Manners, I. J . Am. Chem. Soc. 1992, 114,
6246. (g) Casado, C. M.; Cuadrado, I.; Mora´n, M.; Alonso, B.; Lobete,
F.; Losada, J . Organometallics 1995, 14, 2618. (h) Altmann, M.;
Enkelmann, V.; Beer, F.; Bunz, U. H. W. Organometallics 1996, 15,
394. (i) Altmann, M.; Bunz, U. H. W. Angew. Chem., Int. Ed. Engl.
1995, 34, 569. (j) Bunz, U. H. W. Angew. Chem., Int. Ed. Engl. 1996,
35, 969. (k) Gleiter, R.; Stahr, H.; Nuber, B. Organometallics 1997,
16, 646. (l) Cerveau, G.; Corriu, R. J . P.; Lepeytre, C. J . Mater. Chem.
1995, 5, 793. (m) Seyferth, D.; Kugita, T.; Rheingold, A.; Yap, G. P. A.
Organometallics 1995, 14, 5362. (n) Cuadrado, I.; Mora´n, M.; Moya,
A.; Casado, C. M.; Barranco, M.; Alonso, B. Inorg. Chim. Acta 1996,
251, 5. (o) Lobete, F.; Cuadrado, I.; Casado, C. M.; Alonso, B.; Mora´n,
M.; Losada, J . J . Organomet. Chem. 1996, 509, 109.
The desired cobalt-complexed 1,3-dioxa-2-silacyclo-
alkynes were successfully prepared using synthetic
methods similar to those detailed by Cragg and co-
workers.6 In the presence of triethylamine, treatment
of 2-butyne-1,4-diol-hexacarbonyldicobalt with the ap-
propriate dichlorodialkylsilane resulted in facile ring
closure, producing compounds 3-7 as the major prod-
ucts (Chart 1). These compounds were accompanied by
the formation of small quantities of nine-membered ring
siloxanes (8 in the preparation of 3) that likely result
(4) (a) Nicholas, K. N.; Pettit, R. Tetrahedron Lett. 1971, 37, 3475.
(b) Magnus, P. Polyhedron 1994, 50, 1397.
(2) (a) Kuhnen, T.; Ruffolo, R.; Stradiotto, M.; Ulbrich, D.; McGlinchey,
M. J .; Brook, M. A. Organometallics 1997, 16, 5042. (b) Kuhnen, T.;
Stradiotto, M.; Ruffolo, R.; Ulbrich, D.; McGlinchey, M. J .; Brook, M.
A. Organometallics 1997, 16, 5048.
(3) (a) Cotton, F. A.; Wilkinson, G. Advanced Inorganic Chemistry,
5th ed.; Wiley-Interscience: Toronto, 1988. (b) Shriver, D. F.; Kaesz,
H. D.; Adams, R. D. The Chemistry of Metal Cluster Complexes; VCH
Publishers: New York, 1990.
(5) (a) Diederich, F. Nature 1994, 369, 199. (b) Diederich, F.; Rubin,
Y.; Chapman, O. L.; Goroff, N. S. Helv. Chim. Acta 1994, 77, 1441. (c)
Schreiber, S. L.; Sammakia, T.; Crowe, W. E. J . Am. Chem. Soc. 1986,
108, 3128. (d) Ruffolo, R.; Brook, M. A.; McGlinchey, M. J . Organo-
metallics 1998, 17, 4992.
(6) (a) Cragg, R. H.; J effery, J . C.; Went, M. J . J . Chem. Soc., Chem.
Commun. 1990, 993. (b) Cragg, R. H.; J effery, J . C.; Went, M. J . J .
Chem. Soc., Dalton Trans. 1991, 137.
10.1021/om980589z CCC: $15.00 © 1998 American Chemical Society
Publication on Web 11/03/1998

Co2(CO)6-Complexed 1,3-Dioxa-2-silacycloheptynes
Organometallics, Vol. 17, No. 24, 1998 5343
Sch em e 1. Syn th esis a n d Dim er iza tion of
Coba lt-Com p lexed 1,3-Dioxa -2-sila cycloh ep tyn es
F igu r e 1. Crystallographically determined structure of 3
(shown with 30% thermal displacement ellipsoids).
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 3 a n d 10
3
10
empirical formula
mol wt
C
22H14Si1Co2O8
C20H8Si1Co4O16
768.07
552.28
description
temp, K
red prism
213(2)
red plate
213(2)
Ch a r t 1
wavelength, Å
cryst syst
space group
a, Å
b, Å
c, Å
(Mo KR) 0.710 73
monoclinic
P21/n
14.8904(7)
6.8276(3)
23.854(1)
105.883(2)
2332.6(2)
4
(Mo KR) 0.710 73
monoclinic
C2/c
25.614(5)
16.959(3)
12.777(3)
100.62(3)
5455(2)
â, deg
volume, Å3
Z
8
calcd density, g/cm3
scan mode
F(000)
1.573
ω-scans
1112
1.870
ω-scans
3024
θ-range for collection,
deg
1.46-22.00
1.45-23.00
index ranges
-16 e h e 16
-7 e k e 6
-26 e l e 26
9793
2856
2833/0/299
-28 e h e 33
-20 e k e 8
-16 e l e 15
9960
3946
3939/0/370
no. of reflns collected
no. of unique reflns
no. of data/restraints/
params
from competitive silylation of the second oxygen prior
to cyclization (Scheme 1C). In the case of 9, the
presence of both meso- and d,l-products (a consequence
of stereogenic silicon centers) could be rationalized on
the basis of 1H NMR spectral data, but these could not
be separated by standard chromatographic techniques.
This proposal was further substantiated by independent
preparation of the racemic product mixture 9 from
2-butyne-1,4-diol-hexacarbonyldicobalt and racemic
(ClMePhSi)2O. With the exception of the asymmetrical
nine-membered ring, 9, the seven- and nine-membered
ring compounds were readily purified by column chro-
matography and isolated in acceptable yields as analyti-
cally pure materials.
goodness-of-fit on F2
final R indices
1.034
0.838
R1 ) 0.0878;
wR2 ) 0.1523
R1 ) 0.1975;
wR2 ) 0.2006
<0.002
R1 ) 0.0547;
wR2 ) 0.1190
R1 ) 0.1155;
wR2 ) 0.1435
0.002
(I > 2s(I))a
R indices (all data)a
mean shift/error
max. shift/error
transmission
<0.002
0.943, 0.833
0.011
0.682, 0.301
(max., min.)
largest diff peak, e/Å3
largest diff hole, e/Å3
0.48
-0.47
0.65
-0.71
R1 ) ∑(|Fo| - |Fc|)/∑|Fo|. wR2 ) [∑[w(Fo2 - Fc2)2]/∑[w(Fo2)2]]0.5
.
a
Given that the symmetry of species such as 1 and 2
makes them difficult to unambiguously differentiate by
use of standard spectroscopic methods,6-8 we chose to
definitively characterize 3 by use of X-ray diffraction
techniques; the structure of 3 is presented as Figure 1,
and relevant data are collected in Tables 1 and 2. The
crystallographically determined structure of 3 serves to
identify the monomeric nature of the product unequivo-
cally. In the solid state, 3 exists in a chairlike confor-
mation and contains a pseudo-mirror-plane which bi-
sects the C(2)-C(3) bond and contains the cobalt and
silicon atoms. This geometry parallels that of related
heterocyclic systems, including 1,3-dioxa-2,2-diphenyl-
2-sila-5,6-benzocycloheptane, described by Hanson and
co-workers.7 On the basis of this crystallographic
structure and mass spectral data, we infer that the
remaining compounds, 4-7, are also seven-membered
(7) Hanson, A. W.; McCulloch, A. W.; McInnes, A. G. Can. J . Chem.
1986, 64, 1450.

5344 Organometallics, Vol. 17, No. 24, 1998
Brook et al.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 3 a n d 10
3
10
Si(1)-O(1)
Si(1)-O(2)
Co(1)-C(2)
Co(1)-C(3)
Co(2)-C(2)
Co(2)-C(3)
Co(1)-Co(2)
C(2)-C(3)
1.652(9)
1.645(8)
1.940(9)
1.961(9)
1.961(9)
1.951(9)
2.480(3)
1.36(2)
Si(1)-O(1)
Si(1)-O(2)
Si(1)-O(3)
Si(1)-O(4)
Co(1)-Co(2)
Co(3)-Co(4)
C(2)-C(3)
C(6)-C(7)
1.615(5)
1.609(5)
1.620(4)
1.627(4)
2.467(1)
2.456(1)
1.335(9)
1.349(8)
C(1)-C(2)-C(3)
C(2)-C(3)-C(4)
O(1)-Si(1)-O(2)
C(5)-Si(1)-C(11)
C(11)-Si(1)-O(1)
C(11)-Si(1)-O(2)
135.4(9)
138.1(9)
113.5(5)
113.7(6)
108.8(6)
110.3(6)
C(1)-C(2)-C(3)
C(2)-C(3)-C(4)
C(5)-C(6)-C(7)
C(6)-C(7)-C(8)
O(1)-Si(1)-O(2)
O(3)-Si(1)-O(4)
137.3(6)
135.6(6)
137.0(6)
137.8(6)
115.5(2)
114.4(2)
Sch em e 2. Syn th etic Rou te to th e Sp ir ocyclic
P r od u ct, 10
F igu r e 2. Crystallographically determined structure of 10
(shown with 30% thermal displacement ellipsoids).
The equilibration of 1,3-dioxa-2-silacycles can be
facile, as elegantly demonstrated by Cragg and co-
workers.8a Many catalysts facilitate this process, par-
ticularly acids and silaphilic nucleophiles,10 and in the
absence of steric constraints arising from substituents
on either the silicon or the cyclic unit, metathesis
leading to larger rings may proceed without catalysis,
a situation we have observed firsthand.11 It remains
to be determined whether the serendipitous presence
of other catalysts, possibly present during workup or
chromatographic purification, may have played a role
in facilitating the isolation of the monomeric species
described herein. Nevertheless, these results clearly
demonstrate that, in contrast to previous reports,6
cobalt-complexed 1,3-dioxa-2-silacycloheptynes can be
efficiently prepared and isolated as monomeric species.
rings. However, it is important to recognize that
crystallographic evidence does exist for the formation
of the cyclic dimers referred to herein. Cragg and co-
workers reported that treatment of the phenyl-substi-
tuted derivative of 2 with 2 equiv of triphenylphosphine
affords a mixture of phosphorus-substituted seven- and
14-membered-ring species, the latter of which has been
structurally characterized.6
In the pursuit of monomeric species that would have
the capacity to act as cross-linking agents,9 the spiro-
cyclic compound 10 was prepared (Scheme 2). By use
of the methodology detailed above, 2 equiv of 2-butyne-
1,4-diol-hexacarbonyldicobalt was allowed to react with
freshly distilled tetrachlorosilane in the presence of
triethylamine. After purification by column chroma-
tography, 10 was isolated as a red crystalline solid that
was characterized by the use of a variety of spectroscopic
techniques and X-ray crystallography; the molecular
structure of 10 is presented as Figure 2. Compound 10
consists of two monomeric (i.e., seven-membered) spi-
rocyclic rings and possesses structural features that
closely parallel those previously discussed for 3.
In light of the fact that our synthetic approach differs
only modestly from that employed by Cragg et al.,
perhaps the most intriguing aspect of these results is
the complete absence of evidence for the formation of
dimeric products, which were previously reported to
predominate in these hexacarbonyldicobalt-based sys-
tems.6 Despite numerous synthetic trials utilizing a
variety of experimental conditions, including a direct
repetition of the procedure employed by Cragg, followed
by careful chromatographic separation on silica, we were
unable to obtain any experimental data in support of
the formation of dimeric products analogous to 2.
Indeed, the mass spectra obtained for compounds 3-7
are consistent with monomeric species, in that no higher
molecular weight peaks are observed.
Exp er im en ta l Section
Gen er a l P r oced u r es. All reactions were carried out under
an atmosphere of dry nitrogen at ambient temperature using
standard Schlenk techniques, unless otherwise stated. Sol-
vents were dried according to established procedures. NMR
spectra were recorded on Bruker AC-200, AC-300, and DRX-
500 spectrometers, with 1H, 13C, and 29Si chemical shifts
reported relative to tetramethylsilane. IR spectra were ob-
tained on a Bio-Rad FTS-40 spectrometer, using NaCl win-
dows. Mass spectra were obtained on a VG Analytical ZAB-
SE spectrometer with an accelerating potential of 8 kV and a
resolving power of 10 000. Microanalytical data were obtained
from Guelph Chemical Laboratories, Guelph, Ontario, Canada.
Octacarbonyldicobalt (Strem), 2-butyne-1,4-diol (Aldrich), and
dichlorodialkylsilanes (Gelest) were used without purification,
while 2-butyne-1,4-diol-hexacarbonyldicobalt was prepared
using a previously published method.12
(10) (a) Bassindale, A. R.; Taylor, P. G. Reaction Mechanisms of
Nucleophilic Attack at Silicon. In The Chemistry of Organic Silicon
Compounds; Patai, S.; Rappoport, Z., Eds.; Wiley: Chichester, U.K.,
1989; Vol. 1, Chapter 13, p 839. (b) Corriu, R. J . P.; Guerin, C.; Moreau,
J . J . E. Dynamic Stereochemistry at Silicon. In The Chemistry of
Organic Silicon Compounds; Patai, S., Rappoport, Z., Eds.; Wiley:
Chichester, U.K., 1989; Vol. 1, Chapter 4, p 305. (c) Sommer, L.
Stereochemistry, Mechanism & Silicon; McGraw-Hill: New York, 1965.
(11) Brook, M. A.; Kremers, C, H.; Sebastian, T.; Yu, W. J . Polym.
Sci., Polym. Lett. 1989, 27, 229.
(8) (a) Cragg, R. H.; Lane, R. D. J . Organomet. Chem. 1984, 268, 1.
(b) Cragg, R. H.; Lane, R. D. J . Organomet. Chem. 1984, 270, 25.
(9) For a recent report on the preparation of spirocyclic precursors
used in the preparation of cross-linked organometallic polymers and
gels, see: MacLachlan, M. J .; Lough, A. J .; Geiger, W. E.; Manners, I.
Organometallics 1998, 17, 1873.
(12) Sternberg, H. W.; Greenfield, H.; Friedel, R. A.; Wotiz, J .;
Markby, R.; Wender, I. J . Am. Chem. Soc. 1954, 76, 1457.

Co2(CO)6-Complexed 1,3-Dioxa-2-silacycloheptynes
Organometallics, Vol. 17, No. 24, 1998 5345
X-r a y Cr ysta llogr a p h y. Crystallographic data13 for 3 and
10 were collected from single-crystal samples, which were
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
SMART) and a rotating anode using graphite-monochromated
Mo KR radiation (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 parameters were determined by a least-squares
fit of the angular settings of the strong reflections, collected
by a 4.5° scan in 15 frames over three different parts of
reciprocal space (45 frames total). One complete hemisphere
of data was collected, to better than 0.8 Å resolution. Process-
ing was carried out by use of the program SAINT, which
applied Lorentz and polarization corrections to three-dimen-
sionally integrated diffraction spots. The program SADABS
was utilized for the scaling of diffraction data, the application
of a decay correction, and an empirical absorption correction
based on redundant reflections. The structure was solved by
using the Patterson method in the Siemens SHELXTL pro-
gram library and refined by full-matrix least-squares methods
with anisotropic thermal parameters for all non-hydrogen
atoms. All hydrogen atoms were added at calculated positions
and refined using a riding model with isotropic displacement
parameters equal to 1.2 times the equivalent isotropic dis-
placement parameter of the attached carbon.
Gen er a l P r ep a r a tion of Com p ou n d s 3-9. To a round-
bottom flask containing 2-butyne-1,4-diol-hexacarbonyldicobalt
(200 mg, 0.54 mmol) and triethylamine (120 mg, 0.17 mL, 1.18
mmol) in either toluene or CH2Cl2 (30 mL) was added the
dichlorodialkylsilane (0.65 mmol (compound 8: 0.55 mmol)).
The dark red solution was stirred at room temperature for 1
h, poured into acidified water (30 mL, pH 6, acidified with
acetic acid), and extracted three times with CH2Cl2 (20 mL).
The organic phase was then dried over Na2SO4, and after
removal of the solvent, the residue was subjected to flash
chromatography on silica gel. Elution with hexane/CH2Cl2
(∼1:1) yielded the desired product, which was dried under
vacuum.
2,2-Dip h en yl-1,3-d ioxa -2-sila cycloh ep t-4-yn e-h exa ca r -
bon yld icoba lt (3). 3 was isolated as red crystals (65% yield),
mp 102 °C (with decomposition). Anal. Calcd for C22H14Co2O8-
Si: C, 47.83; H, 2.55. Found: C, 48.08; H, 2.61. 1H NMR (500
MHz, acetone-d6): δ 5.36 (s, 4H, CH2), 7.45 (m, 6H, phenyl),
7.69 (m, 4H, phenyl). 13C NMR (50 MHz, CD2Cl2, 1H de-
coupled): δ 67.14 (CH2), 96.25 (CtC), 128.74 (phenyl), 131.33
(phenyl), 132.25 (phenyl), 135.09 (phenyl), 199.41 (CtO). 29Si
NMR (99.36 MHz, acetone-d6): δ -23.2. IR (neat): ν/cm-1
1083, 2028, 2056, 2098, 2855, 3010, 3072. MS (DEI, m/z (%)):
468 (48, [M - 3CO]+), 440 (30, [M - 4CO]+), 413 (40, [M -
5CO]+), 384 (100, [M - 6CO]+). MS (CI, m/z (%)): 570 (39,
[MNH4]+), 553 (25, [MH]+), 525 (31, [MH - CO]+), 469 (100,
[MH - 3CO]+), 441 (33, [MH - 4CO]+), 413 (25, [MH - 5CO]+),
385 (50, [MH - 6CO]+). MS (ES, m/z (%)): 552.9 (30, [MH]+),
524.8 (20, [MH - CO]+), 469.0 (35, [MH - 3CO]+). MS (MS/
MS, m/z (%)): 469.1 (80, [MH - 3CO]+), 441.1 (100, [MH -
4CO]+), 412.9 (70, [MH - 5CO]+), 384.9 (55, [MH - 6CO]+).
MS (DEI, m/z, high resolution): calcd for C19H14Co2O5Si ([M
- 3CO]+) 467.9274, obsd 467.9282. Single crystals suitable
for X-ray diffraction analysis (0.06 × 0.04 × 0.03 mm3) were
grown from hexane.
C17H12Co2O8Si: C, 41.65; H, 2.47. Found: C, 42.15; H, 2.75.
1H NMR (500 MHz, acetone-d6): δ 0.38 (s, 3H, CH3), 5.23 (s,
4H, CH2), 7.43 (m, 3H, phenyl), 7.67 (m, 2H, phenyl). 13C NMR
(125 MHz, acetone-d6, 1H decoupled): δ -3.85 (CH3), 66.65
(CH2), 97.38 (CtC), 129.06 (phenyl), 131.47 (phenyl), 134.10
(phenyl), 134.84 (phenyl), 200.55 (CtO). 29Si NMR (99.36
MHz, acetone-d6): δ -9.04. IR (neat): ν/cm-1 1088, 1260,
2024, 2057, 2096, 2851, 2952, 3075. MS (DEI, m/z (%)): 406
(35, [M - 3CO]+), 378 (21, [M - 4CO]+), 350 (31, [M - 5CO]+),
322 (100, [M - 6CO]+). MS (CI, m/z (%)): 491 (25, [MH]+),
463 (25, [MH - CO]+), 407 (100, [MH - 3CO]+), 379 (58, MH
- 4CO]+), 351 (29, [MH - 5CO]+); MS (ES, m/z (%)): 490.8
(100, [MH]+), 462.9 (20, [MH-CO]+), 406.9 (10, [MH-3CO]+).
MS (DEI, m/z, high resolution): calcd for C14H12Co2O5Si ([M-
3CO]+) 405.9138, obsd 405.9118.
2-Eth yl-1,3-d ioxa -2-p h en yl-2-sila cycloh ep t-4-yn e-h exa -
ca r bon yld icoba lt (5). 5 was isolated as red crystals (50%
yield), mp 49 °C (with decomposition). Anal. Calcd for C18H14
-
Co2O8Si: C, 42.87; H, 2.80. Found: C, 43.10; H, 2.79. 1H NMR
(500 MHz, acetone-d6): δ 0.86 (q, 2H, CH2CH3, J ) 6.3 Hz),
0.98 (t, 3H, CH2CH3, J ) 6.3 Hz), 5.25 (s, 4H, CH2), 7.45 (m,
3H, phenyl), 7.68 (m, 2H, phenyl). 13C NMR (50 MHz, acetone-
d6, 1H decoupled): δ 6.07 (CH2CH3), 6.39 (CH2CH3), 66.81
(OCH2), 97.30 (CtC), 129.16 (phenyl), 131.47 (phenyl), 132.66
(phenyl), 135.27 (phenyl), 200.43 (CtO). IR (neat): ν/cm-1
1087, 1247, 2019, 2060, 2097, 2869, 2957, 3022, 3076. MS
(DEI, m/z (%)): 420 (50, [M - 3CO]+), 364 (39, [M - 5CO]+),
336 (100, [M - 6CO]+); MS (CI, m/z (%)): 505 (42, [MH]+),
477 (25, [MH - CO]+), 421 (100, [MH - 3CO]+), 393 (17, [MH
- 5CO]+). MS (DEI, m/z, high resolution): calcd for C15H14
Co2O5Si ([M - 3CO]+) 419.9274, obsd 419.9280.
-
2,2-Dim eth yl-1,3-d ioxa -2-sila cycloh ep t-5-yn e-h exa ca r -
bon yld icoba lt (6). 6 was previously reported by Cragg and
co-workers6 and isolated as a viscous red oil (40% yield). 1H
NMR (200 MHz, acetone-d6): δ 0.20 (s, 6H, CH3), 5.09 (s, 4H,
CH2). 13C NMR (50 MHz, acetone-d6, 1H decoupled): δ -3.82
(CH3), 66.98 (CH2), 97.75 (CtC), 200.40 (CtO). 29Si NMR
(99.36 MHz, acetone-d6): δ 5.96. IR (neat): ν/cm-1 1091, 1261,
2025, 2057, 2097, 2852, 2929. MS (DEI, m/z (%)): 344 (50,
[M - 3CO]+), 288 (60, [M - 5CO]+), 260 (100, [M - 6CO]+);
MS (CI, m/z (%)): 429 (100, [MH]+), 401 (60, [MH - CO]+).
MS (DEI, m/z, high resolution): calcd for C9H10Co2O5Si ([M -
3CO]+) 343.8961, obsd 343.8970.
2-Meth yl-1,3-d ioxa -2-sila -2-vin ylcycloh ep t-4-yn e-h exa -
ca r bon yld icoba lt (7). 7 was isolated as a viscous red oil
(52% yield). Anal. Calcd for C13H10Co2O8Si: C, 35.47; H, 2.29.
Found: C, 35.52; H, 2.35. 1H NMR (200 MHz, acetone-d6): δ
0.23 (s, 3H, CH3), 5.15 (s, 4H, CH2), 6.11 (m, 3H, CHdCH2).
13C NMR (50 MHz, acetone-d6, 1H decoupled): δ -4.23 (CH3),
66.36 (CH2), 97.51 (CtC), 133.19 (CHdCH2), 136.97 (CHdCH2),
200.26 (CtO). 29Si NMR (99.36 MHz, acetone-d6): δ -9.68.
IR (neat): ν/cm-1 1090, 1264, 2024, 2057, 2097, 2852, 2950,
3060. MS (DEI, m/z (%)): 384 (22, [M - 2CO]+), 356 (27, [M
- 3CO]+), 328 (40, [M - 4CO]+), 300 (71, [M - 5CO]+), 272
(100, [M - 6CO]+); MS (CI, m/z (%)): 441 (100, [MH]+), 413
(9, [MH - CO]+), 385 (10, [MH - 2CO]+), 357 (22, [MH -
3CO]+). MS (DEI, m/z, high resolution): calcd for C11H10Co2O6-
Si ([M - 2CO]+) 383.8911, obsd 383.8920.
2,2,4,4-Tet r a p h en yl-1,3,5-t r ioxa -2,4-d isila cyclon on -6-
yn e-h exa ca r bon yld icoba lt (8). 8 was isolated as a byprod-
uct by column chromatography as a viscous red oil (10% yield).
Anal. Calcd for C34H24Co2O9Si2: C, 54.40; H, 3.23. Found:
C, 54.14; H, 3.41. 1H NMR (200 MHz, acetone-d6): δ 5.22 (s,
4H, CH2), 7.45 (m, 12H, phenyl), 7.73 (m, 8H, phenyl). 13C
NMR (50 MHz, acetone-d6, 1H decoupled): δ 65.37 (CH2), 95.78
(CtC), 128.84 (phenyl), 131.52 (phenyl), 133.88 (phenyl),
135.52 (phenyl), 200.49 (CtO). 29Si NMR (99.36 MHz, acetone-
d6): δ -36.0. IR (neat): ν/cm-1 1084, 2031, 2054, 2094, 2844,
2933, 2963, 3015, 3071. MS (CI, m/z (%)): 751 (24, [MH]+),
667 (100, [MH - 3CO]+), 639 (52, [MH - 4CO]+), 611 (100,
[MH - 5CO]+), 583 (95, [MH - 6CO]+).
2-Me t h yl-1,3-d ioxa -2-p h e n yl-2-sila cycloh e p t -4-yn e -
h exa ca r bon yld icoba lt (4). 4 was isolated as red crystals
(52% yield), mp 48 °C (with decomposition). Anal. Calcd for
(13) (a) SMART 1996, Release 4.05; Siemens Energy And Automa-
tion Inc.: Madison, WI 53719, 1996. (b) SAINT 1996, Release 4.05;
Siemens Energy and Automation Inc.: Madison, WI 53719, 1996. (c)
Sheldrick, G. SADABS (Siemens Area Detector Absorption Correc-
tions), 1996. (d) SHELXTL 1994, Version 5.03; Siemens Crystal-
lographic Research Systems: Madison, WI 53719, 1994.

5346 Organometallics, Vol. 17, No. 24, 1998
Brook et al.
2,4-Dim eth yl-1,3,5-tr ioxa -2,4-d ip h en yl-2,4-d isila cyclo-
n on -6-yn e-h exa ca r bon yld icoba lt (9). 9 was isolated as a
viscous red oil (71% yield). Anal. Calcd for C24H20Co2O9Si2:
C, 46.01; H, 3.22. Found: C, 46.23; H, 3.00. 1H NMR (200
MHz, acetone-d6): δ 0.34 (s, 3H, CH3), 0.47 (s, 3H, CH3), 5.07
(s, 2H, CH2), 5.11 (s, 2H, CH2), 7.39 (m, 6H, phenyl), 7.70 (m,
4H, phenyl). 13C NMR (50 MHz, acetone-d6, 1H decoupled): δ
-1.81 (CH3), -1.77 (CH3), 64.45 (CH2), 64.59 (CH2), 96.11
(CtC), 96.33 (CtC), 128.87-135.94 (phenyl), 200.63 (CtO).
29Si NMR (99.36 MHz, acetone-d6): δ -23.2, -22.7. IR
(neat): ν/cm-1 1082, 1261, 2023, 2055, 2093, 2843, 2933, 2966,
3023, 3073. MS (CI, m/z (%)): 627 (53, [MH]+), 599 (10, [MH
- CO]+), 543 (100, [MH - 3CO]+), 515 (20, [MH - 4CO]+),
487 (47, [MH - 5CO]+), 459 (16, [MH - 6CO]+). MS (DEI,
m/z, high resolution): calcd for C21H20Co2O6Si ([M - 3CO]+)
541.9462, obsd 541.9463.
Sp ir obicycloh ep tyn e-bis(h exa ca r bon yld icoba lt) (10).
To a flask containing 2-butyne-1,4-diol-hexacarbonyldicobalt
(300 mg, 0.8 mmol) in CH2Cl2 (30 mL) was added triethylamine
(0.33 g, 3.28 mmol, 0.45 mL). Freshly distilled SiCl4 (70 mg,
0.4 mmol, 0.046 mL) was diluted to 1 mL (CH2Cl2) and added
dropwise to the solution of the diol. The dark red solution was
stirred for 30 min, then poured into water (pH 6, acidified with
acetic acid and saturated with NaCl). After extracting the
aqueous phase three times with CH2Cl2 (30 mL), the combined
organic phases were dried over NaSO4 and evaporated to give
the crude product, which was chromatographed on silica gel
(CH2Cl2/hexanes, 3:1) and isolated as red crystals (16% yield).
Anal. Calcd for C20H8Co4O16Si: C, 31.26; H, 1.05. Found: C,
31.52; H, 0.83. Mp: decomposes between 90 and 110 °C. 1H
NMR (200 MHz, acetone-d6): δ 5.23 (s, 8H, CH2). 13C NMR
(50 MHz, acetone d6, 1H decoupled): δ 66.68 (CH2), 95.18
(CtC), 199.70 (CtO). 29Si NMR (99.36 MHz, acetone-d6): δ
-70.2. IR (neat): ν/cm-1 2021, 2060, 2098. Single crystals
suitable for X-ray diffraction analysis (0.30 × 0.20 × 0.08 mm3)
were grown from CH2Cl2.
Ackn owledgm en t. Financial support from the Natu-
ral Sciences and Engineering Research Council (NSERC)
of Canada, including an NSERC postgraduate (PGS-B)
scholarship (M.S.), and from the Deutsche Akademische
Austauschdienst (J .U.), is gratefully acknowledged.
Mass spectrometric data were obtained courtesy of Dr.
Richard Smith of the McMaster Regional Center for
Mass Spectrometry.
Su p p or tin g In for m a tion Ava ila ble: Atomic coordinates,
bond lengths and angles, anisotropic displacement parameters,
and hydrogen atom coordinates for 3 and 10 (12 pages).
Ordering information is given on any current masthead page.
OM980589Z