Synthesis and catalytic activity of group 4 metallocene containing silsesquioxanes bearing functionalized silyl groups

Article abstract of DOI:10.1021/om040082q

A series of metallocene-containing silsesquioxanes with alkenylsilyl and trimethylsilyl groups, Cp′₂M[(c-C₅H ₉)₇Si₇O₁₁](OSiMe₂R) (2b-d, 3b-d, 4d, 5d: Cp′ = Cp (cyclopentadienyl), Cp* (pentamethylcyclopentadienyl); M = Ti, Zr, Hf, R = methyl, vinyl, allyl), have been synthesized. The structures of the complexes Cp₂M[(c-C ₅H₉)₇Si₇O₁₁](OSiMe ₂CH₂CH=CH₂) (M = Zr (3d), Hf (5d)) have been unambiguously established by single-crystal X-ray diffraction analyses. Silylation or germylation of the zirconocene-containing silsesquioxane monosilanol Cp₂Zr[(c-C₅H₉)₇Si ₇O₁₁](OH) (3a) or its hafnocene derivative Cp ₂Hf[(c-C₅H₉)₇-Si₇O ₁₁](OH) (5a), which can be prepared by the careful reaction of the silsesquioxane trisilanol (c-C₅H₉)₇Si ₇O₉(OH)₃ (1a) with zirconocene dichloride or hafnocene dichloride, yields the new series of metallocene-containing silsesquioxanes Cp₂Zr[(c-C₅H₉) ₇Si₇O₁₁](OSiMe₂H) (3e), Cp ₂-Zr[(c-C₅H₉)₇Si₇O ₁₁](OGeMe₃) (3f), and Cp₂Hf[(c-C ₅H₉)₇Si₇O₁₁](OSiMe ₂H) (5e). The reaction of 3e with 2 equiv of hydrogen chloride results in the formation of the dimethylsilyl-containing silsesquioxane disilanol (c-C₅H₉)₇Si₇O ₉(OH)₂(OSiMe₂H) (1e), indicating the applicability of metallocene moieties as protecting groups of two adjacent silanol groups. Silsesquioxanes bearing alkenylsilyl groups can be easily converted to derivatives with ethoxysilyl groups, Cp₂M[(c-C ₅H₉)₇Si₇O₁₁] [OSiMe ₂(CH₂)₃SiMe₂(OEt)] (M = Ti (2g), Zr (3g)), by the hydrosilylative reaction. The preliminary examination of the catalytic activity of these metallocene-containing silsesquioxanes toward the epoxidation of cyclohexene by tert-butyl hydroperoxide revealed that titanocene-containing silsesquioxanes (2b-d) show modest catalytic activity. The presence of alkenylsilyl groups has been found to accelerate the reactions, especially in the case of titanium-bridged silsesquioxanes.

Full text of DOI:10.1021/om040082q

5824
Organometallics 2004, 23, 5824-5832
Synthesis and Catalytic Activity of Group 4 Metallocene
Containing Silsesquioxanes Bearing Functionalized Silyl
Groups
Kenji Wada,* Naohiko Itayama, Naoki Watanabe, Masaki Bundo,
Teruyuki Kondo, and Take-aki Mitsudo*
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering,
Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
Received June 4, 2004
A series of metallocene-containing silsesquioxanes with alkenylsilyl and trimethylsilyl
groups, Cp′ M[(c-C H ) Si O11](OSiMe R) (2b-d, 3b-d, 4d, 5d: Cp′ ) Cp (cyclopentadienyl),
2 5 9 7 7 2
Cp* (pentamethylcyclopentadienyl); M ) Ti, Zr, Hf, R ) methyl, vinyl, allyl), have been
synthesized. The structures of the complexes Cp M[(c-C Si 11](OSiMe CH CHdCH
M ) Zr (3d), Hf (5d)) have been unambiguously established by single-crystal X-ray
diffraction analyses. Silylation or germylation of the zirconocene-containing silsesquioxane
monosilanol Cp Zr[(c-C Si 11](OH) (3a) or its hafnocene derivative Cp Hf[(c-C
Si 11](OH) (5a), which can be prepared by the careful reaction of the silsesquioxane trisilanol
c-C Si (OH) (1a) with zirconocene dichloride or hafnocene dichloride, yields the new
series of metallocene-containing silsesquioxanes Cp Zr[(c-C Si 11](OSiMe H) (3e), Cp
Zr[(c-C Si 11](OGeMe ) (3f), and Cp Hf[(c-C Si 11](OSiMe H) (5e). The reaction
of 3e with 2 equiv of hydrogen chloride results in the formation of the dimethylsilyl-containing
silsesquioxane disilanol (c-C Si (OH) (OSiMe H) (1e), indicating the applicability of
2
5 9
H )
7
7
O
2
2
2
)
(
2
5
H
9
)
7
7
O
2
5 9 7
H ) -
7
O
5
(
H
9
)
7
7
O
9
3
2
5
H )
9 7
7
O
2
2
-
5
H
9
)
7
7
O
3
2
5
H
9
)
7
7
O
2
5
H
9
)
7
7
O
9
2
2
metallocene moieties as protecting groups of two adjacent silanol groups. Silsesquioxanes
bearing alkenylsilyl groups can be easily converted to derivatives with ethoxysilyl groups,
2 5 9 7 7 2 2 3 2
Cp M[(c-C H ) Si O11][OSiMe (CH ) SiMe (OEt)] (M ) Ti (2g), Zr (3g)), by the hydrosilylative
reaction. The preliminary examination of the catalytic activity of these metallocene-containing
silsesquioxanes toward the epoxidation of cyclohexene by tert-butyl hydroperoxide revealed
that titanocene-containing silsesquioxanes (2b-d) show modest catalytic activity. The
presence of alkenylsilyl groups has been found to accelerate the reactions, especially in the
case of titanium-bridged silsesquioxanes.
6
Introduction
Silica-supported transition-metal catalysts play sig-
nificant roles in current chemical industries. Supported
group 4 metal containing catalysts are now widely used
oxanes have attracted much attention from the view-
point of discrete, well-defined soluble model compounds
of the transition-metal-containing siliceous heteroge-
1
7
neous catalysts. Recent studies by us and other re-
search groups
class of compounds as homogeneous catalysts in organic
synthesis. With regard to the group 4 transition metal
6a,d,e,g,8,9
have revealed the utility of this
2
for a number of important reactions: i.e., oxidation,
3
4
alkene polymerization, degradation of polyolefins, and
so on. For the preparation of active heterogeneous
catalysts, a precise understanding of the nature of active
sites and/or mechanisms of catalytic reactions is crucial.
Despite the recent marked developments in surface
science, difficulties still remain in the strict control of
their active sites.
(
5) For a representative review, see: Baney, R. H.; Itoh, M.;
Sakakibara, A.; Suzuki, T. Chem. Rev. 1995, 95, 1409.
6) For reviews, see: (a) Feher, F. J.; Budzichowski, T. A. Polyhedron
(
1995, 14, 3239. (b) Murugavel, R.; Voigt, A.; Walawalkar, M. G.;
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J. 2000, 6, 25. (e) Mitsudo, T.; Wada, K. Shokubai 2000, 42, 282. (f)
Lorenz, V.; Fischer, A.; Giessmann, S.; Gilje, J. W.; Gun’ko, Y.; Jacob,
K.; Edelmann, F. T. Coord. Chem. Rev. 2000, 206-207, 321. (g)
Duchateau, R. Chem. Rev. 2002, 102, 3525.
Recently, incompletely condensed oligosilsesquioxanes
5
with silanol groups and metal-containing silsesqui-
(
7) (a) Wada, K.; Nakashita, M.; Yamamoto, A.; Wada, H.; Mitsudo,
*
To whom correspondence should be addressed. E-mail: mitsudo@
scl.kyoto-u.ac.jp (T.M.).
1) Weissermel, K.; Arpe, H. J. Industrial Organic Chemistry, 4th
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Commun. 1997, 331. (b) Maschmeyer, T.; Klunduk, M. C.; Martin, C.
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1997, 1847. (c) Crocker, M.; Herold, R. H. M.; Orpen, A. G. Chem.
Commun. 1997, 2411. (d) Thomas, J. M.; Sankar, G.; Klunduk, M. C.;
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Chem. B 1999, 103, 8809-8813. (e) Crocker, M.; Herold, R. H. M.;
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740.
(
(
(
1
G.; Steinmetz, B.; Zechlin, J.; Przybyla, C.; Tesche, B. Chem. Rev. 2000,
1
3
00, 1377. (d) Kaminsky, W.; Hartmann, F. Angew. Chem. 2000, 122,
39; Angew. Chem., Int. Ed. 2000, 39, 331.
(
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1
0.1021/om040082q CCC: $27.50 © 2004 American Chemical Society
Publication on Web 10/14/2004

Group 4 Metallocene Containing Silsesquioxanes
Organometallics, Vol. 23, No. 24, 2004 5825
containing silsesquioxanes the catalytic activities for the
a limited number of metal-containing silsesquioxanes
with other functional groups.
6
d,e,8
11b,13d,17
epoxidation of alkenes
and polymerization of small
6a,g,9
9b,d,10
alkenes
zirconium,
have been reported. Several titanium,
In preliminary studies, we have prepared several
group 4 metal containing molecular silsesquioxanes
bearing alkenylsilyl groups.1 These silsesquioxanes
have been further applied to the preparation of macro-
9
b,c,10f,11
10b,12
and hafnium-containing
silses-
1b
quioxanes bearing cyclopentadienyl ligands have been
prepared, and some of them have been revealed to be
8
a,9,10f,11c,d
18
19
effective catalysts.
cyclic molecules and polymeric materials. In the
present paper, we have extended the previous studies
to the synthesis of a series of group 4 metallocene
containing silsesquioxanes with functional silyl or ger-
myl groups. The structures of two group 4 metal
containing silsesquioxanes are established by X-ray
crystallographic studies. Included in this report is the
preparation of silsesquioxanes with vinylsilyl, allylsilyl,
hydridosilyl, or trimethylgermyl groups via different
pathways, as well as the introduction of alkoxysilyl
groups. The catalytic activities of some of these metal-
locene-containing silsesquioxanes for the epoxidation of
cyclohexene are also briefly discussed.
In addition to their utility as homogeneous catalysts,
these silsesquioxanes have been found to be an excellent
source of heterogeneous catalysts.11b,13-16 For example,
we have found that controlled calcination of metallasils-
esquioxanes yields mixed oxides of well-dispersed me-
tallic species and characteristic pore structures.14 After
the reports by us, several research groups reported the
preparation of oxide catalysts from silsesquioxanes.15
There are other methods for the preparation of hetero-
geneous catalysts utilizing metallasilsesquioxanes. For
example, immobilization onto other materials, polym-
erization, or incorporation into sol-gel matrixes of
metallasilsesquioxanes seem to be promising methods
to prepare catalysts with well-defined structures of the
1
1b,13
Results and Discussion
active sites.
For this purpose introduction of ap-
propriate functional groups, i.e., alkenylsilyl or alkoxy-
silyl groups, is of importance. There are, however, only
Synthesis of Group 4 Metallocene Containing
Silsesquioxanes Bearing Functionalized Silyl
Groups. A series of group 4 transition metal containing
silsesquioxanes including alkenylsilyl groups were pre-
pared by the reaction of the disilanols (c-C5H9)7Si7O9-
(OH)2(OSiMe2R) (1c, R ) vinyl; 1d, R ) allyl) with the
corresponding metallocene dichlorides. Disilanols 1c,d
can be prepared easily by the direct, kinetically con-
trolled monosilylation of a silsesquioxane triol, (c-C5H9)7-
Si7O9(OH)3 (1a), using 0.6 equiv of chlorodimethylvi-
nylsilane or allylchlorodimethylsilane. On the other
hand, the preparation of (c-C5H9)7Si7O9(OH)2(OSiMe2H)
(
9) (a) Duchateau, R.; Abbenhuis, H. C. L.; van Santen, R. A.;
Meetsma, A.; Thiele, S. K.-H.; van Tol, M. F. H. Organometallics 1998,
1
7, 5663. (b) Duchateau, R.; Cremer, U.; Harmsen, R. J.; Mohamud,
S. I.; Abbenhuis, H. C. L.; van Santen, R. A.; Meetsma, A.; Thiele, S.
K.-H.; van Tol, M. F. H.; Kranenburg, M. Organometallics 1999, 18,
5
447. (c) Duchateau, R.; van Santen, R. A.; Yap, G. P. A. Organome-
tallics 2000, 19, 809. (d) Severn, J. R.; Duchateau, R.; van Santen, R.
A.; Ellis, D. D.; Spek, A. L.; Yap, G. P. A. Dalton 2003, 2293.
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W. J. Am. Chem. Soc. 1992, 114, 3859. (b) Buys, I. E.; Hambley, T.
W.; Houlton, D. J.; Maschmeyer, T.; Masters, A. F.; Smith, A. K. J.
Mol. Catal. 1994, 86, 309. (c) Field, L. D.; Lindall, C. M.; Maschmeyer,
T.; Masters, A. F. Aust. J. Chem. 1994, 47, 1127. (d) Feher, F. J.;
Rahimian, K.; Budzichowski, T. A.; Ziller, J. W. Organometallics 1995,
(1e) or (c-C5H9)7Si7O9(OH)2(OGeMe3) (1f) cannot be
4
, 3920. (e) Edelmann, F. T.; Giessmann, S.; Fischer, A. Chem.
Commun. 2000, 2153. (f) Edelmann, F. T.; Giessmann, S.; Fischer, A.
J. Organomet. Chem. 2001, 620, 80. (g) Kim, Y.; Han, Y.; Lee, M. H.;
Yoon, S. W.; Choi, K. H.; Song, B. G.; Do, Y. Macromol. Rapid Commun.
achieved by the direct silylation or germylation of 1a.
Even the reaction of 1a with 0.1 equiv of ClSiMe2H
produces a mixture of mono-, di-, and trisilylated
products together with a small amount of decomposed
products. Complete isolation of 1e from the reaction
mixture has not been successful yet. Instead, (c-C5H9)7-
Si7O9(OSiMe2H)3 was isolated by the recrystallization.
Note that an alternative “indirect” method successfully
produces 1e (see below).
2
001, 22, 573.
11) (a) Feher, F. J. J. Am. Chem. Soc. 1986, 108, 3850. (b) Wada,
(
K.; Bundo, M.; Nakabayashi, D.; Itayama, N.; Kondo, T.; Mitsudo, T.
Chem. Lett. 2000, 628. (c) Skowronska-Ptasinska, M. D.; Duchateau,
R.; van Santen, R. A.; Yap, G. P. A. Organometallics 2001, 20, 3519.
(
d) Metcalfe, R. A.; Kreller, D. I.; Tian, J.; Kim, H.; Taylor, N. J.;
Corrigan, J. F.; Collins, S. Organometallics 2002, 21, 1719.
12) Gun’ko, Y. K.; Nagy, L.; Bruser, W.; Lorenz, V.; Fischer, A.;
Giessmann, S.; Edelmann, F. T.; Jacob, K.; Vertes, A. Monatsh. Chem.
999, 130, 45.
13) (a) Abbenhuis, H. C. L.; van Herwijnen, H. W. G.; van Santen,
(
1
11b
As reported previously, no attempts at the synthe-
(
R. A. Chem. Commun. 1996, 1941. (b) Krijnen, S.; Abbenhuis, H. C.
L.; Hanssen, R. W. J. M.; van Hooff, J. H. C.; van Santen, R. A. Angew.
Chem. 1998, 110, 374; Angew. Chem., Int. Ed. 1998, 37, 356. (c)
Krijnen, S.; Mojet, B. L.; Abbenhuis, H. C. L.; van Hooff, J. H. C.; van
Santen, R. A. Phys. Chem. Chem. Phys. 1999, 1, 361. (d) Skowronska-
Ptasinska, M. D.; Vorstenbosch, M. L. W.; van Santen, R. A.; Abben-
huis, H. C. L. Angew. Chem. 2002, 114, 659; Angew. Chem., Int. Ed.
sis of titanocene-containing silsesquioxanes by the reac-
tion of titanocene dichloride with 1b-d in chloroform,
dichloromethane, or 1,2-dichloroethane were successful.
The reactions of titanocene dichloride with a thallium-
containing silsesquioxane, (c-C5H9)7Si7O9(OTl)2(OSiMe3),
also did not proceed. Our recent attempted reaction in
toluene for 3 days in the presence of excess trieth-
ylamine cleanly produced the titanocene-containing
silsesquioxanes 2b-d in moderate yields (eq 1). The
structures of these silsesquioxanes have been deduced
2
002, 41, 637.
14) (a) Wada, K.; Nakashita, M.; Yamamoto, A.; Mitsudo, T. Chem.
(
Commun. 1998, 133. (b) Wada, K.; Nakashita, M.; Bundo, M.; Ito, K.;
Kondo, T.; Mitsudo, T. Chem. Lett. 1998, 659. (c) Wada, K.; Yamada,
K.; Kondo, T.; Mitsudo, T. Chem. Lett. 2001, 12. (d) Wada, K.; Yamada,
K.; Kondo, T.; Mitsudo, T. J. Jpn. Petrol. Inst. 2002, 45, 15.
(15) (a) Maxim, N.; Abbenhuis, H. C. L.; Stobbelaar, P. J.; Mojet, B.
1
13
29
on the basis of H, C, and Si NMR and FAB-MS
analyses. The 13C NMR spectra indicate the presence
of two nonequivalent Cp rings and five resonances in a
L.; van Santen, R. A. Phys. Chem. Chem. Phys. 1999, 1, 4473. (b)
Maxim, N.; Abbenhuis, H. C. L.; Magusin, P. C. M. M.; van Santen, R.
A. Chin. J. Chem. 2001, 19, 30. (c) Maxim, N.; Magusin, P. C. M. M.;
Kooyman, P. J.; van Wolput, J. H. M. C.; van Santen, R. A. Abbenhuis,
H. C. L. Chem. Mater. 2001, 13, 2958. (d) Maxim, N.; Overweg, A.;
Kooyman, P. J,; van Wolput, J. H. M. C.; Hanssen, R. W. J. M.; van
Santen, R. A.; Abbenhuis, H. C. L. J. Phys. Chem. 2002, 106, 2203. (e)
Maxim, N.; Overweg, A.; Kooyman, P. J.; Nagy, A.; van Santen, R. A.;
Abbenhuis, H. C. L. J. Mater. Chem. 2002, 12, 3792. (f) Murugavel,
R.; Davis, P.; Shete, V. Inorg. Chem. 2003, 42, 4696.
(17) (a) Feher, F. J.; Phillips, S. H. J. Organomet. Chem. 1996, 521,
401. (b) Feher, F. J.; Terroba, R.; Ziller, J. W. Chem. Commun. 1999,
2153.
(18) Wada, K.; Izuhara, D.; Yamada, K.; Shiotsuki, M.; Kondo, T.;
Mitsudo, T. Chem. Commun. 2001, 1802.
(19) Wada, K.; Yamada, K.; Izuhara, D.; Kondo, T.; Mitsudo, T.
Chem. Lett. 2000, 1332.
(
16) Imizu, Y.; Takahara, K.; Okazaki, N.; Itoh, H.; Tada, A.;
Ohnishi, R.; Ichikawa, M. Stud. Surf. Sci. Catal. 1994, 90, 339.

5826 Organometallics, Vol. 23, No. 24, 2004
Wada et al.
1
:2:2:1:1 ratio for the ipso carbon atoms in the cyclo-
Table 1. Catalytic Activities of Group 4 Transition
Metal Containing Silsesquioxanes for the
Epoxidation of Cyclohexenea
2
9
pentyl rings. The Si NMR spectra of these molecules
consist of four peaks in a 1:3:1:2 ratio for the silicon
catalyst
temp, °C
yield of epoxide, %
2
2
2
3
7
8
8
8
7
8
b
50
50
50
50
50
50
50
50
60
60
22
c
25
d
28
b
trace
66
b
b
c
15
30
d
33
b
76
d
64
a
Conditions: catalyst 1.0 mol %, cyclohexene 3.3 mmol in
3
t
3
toluene (1.5 cm ), BuOOH (3.3 mmol) in decane (0.6 cm ), 4 h,
b
under Ar. The activity of a cyclohexyl analogue of 7 has been
8
a
reported.
Experimental Section and Tables 2-4. A thermal el-
lipsoid plot of 3d is shown in Figure 1. An allyl group
atoms in the silsesquioxane cages, consistent with the
local Cs symmetry of their siloxane backbone. Although
the reaction of titanocene dichloride with silsesquioxane
silanols has been examined for years by several re-
searchers, the formation of bipodal tetravalent ti-
tanocene-containing silsesquioxanes such as 2b has not
been reported before. Instead, various more complicated
titanium-containing silsesquioxanes were produced. For
example, Edelmann et al. have reported the forma-
tion of a dimeric titanium-containing silsesquioxane,
{
(c-C6H11)7Si7O9(OSiMe3)(OTiCp2)}2(µ-O), by the reac-
tion of titanocene dichloride and a silsesquioxane disi-
lanol with peripheral cyclohexyl groups, (c-C6H11)7Si7O9-
10f
(
OH)2(OSiMe3), under conditions almost identical with
those of the present reactions. They also reported that
the reactions were not straightforward and usually
resulted in the formation of product mixtures.10f Al-
though the exact reason for the different results is still
not clear, this can be an interesting example of the
selection of the products by changing the peripheral
organic substitutent of the silsesquioxane cage. A sils-
esquioxane including a trivalent titanocene group has
is located at the opposite side of the zirconium atom.
Other parts of the structure are almost identical with
the structures of previously reported Cp2Zr[(c-C5H9)7-
Si7O11](OSiMe3) (3b)1 and its dimethylphenylsilyl
derivative Cp2Zr[(c-C5H9)7Si7O11](OSiMe2Ph).1 The
structure around the zirconium atom is represented by
a pseudo-tetrahedron, and the centroids of Cp rings and
the Zr, Si(2), Si(5), Si(7), and Si(8) atoms are located
nearly on the same plane. The Zr-O bond distances
(1.988(5) and 1.986(5) Å) are within the range observed
for other silsesquioxanes with cubic core structures
1b
1c
1
0e
been synthesized recently.
On the other hand, the reaction of zirconocene dichlo-
ride with 1c,d, as well as the trimethylsilyl-substituted
disilanol 1b, proceeds more smoothly in the presence
of excess triethylamine in chloroform at room temper-
ature to produce the zirconocene-containing silsesqui-
oxanes 3b-d in high yields (eq 2). The reactions usually
containing cyclopentadienylzirconium moieties, Cp*Zr-
1
13
11a
require less than 1 h for completion. The H, C, and
(c-C6H11)7Si7O12 (1.985(6) Å),
Zr[(c-C5H9)7Si7O11-
29
9a
Si NMR spectra of 3b-d are very close to those of 2b-
(OSiMe3)]2‚DME (2.00 Å average), {PhCH2Zr[(c-C5H9)7-
9a
d, indicating their structural similarities. The reaction
of the more sterically demanding Cp*2ZrCl2 with a
disilanol (1d) also proceeds smoothly to yield the cor-
responding Cp*2Zr-containing molecule (4d).
Si7O12]}2 (1.96 Å average), 3b (1.96(1) and 1.96(1)
11b
Å),
and 1.995(2) Å).
around the zirconium atom are also in the range
and Cp2Zr[(c-C5H9)7Si7O11](OSiMe2Ph) (1.994(2)
11c
Other bond distances and angles
9
a,11b,c
Colorless crystals of 3d of sufficient quality for X-ray
crystallographic analysis were grown by slow diffusion
of acetonitrile into a concentrated mesitylene solution
at room temperature. Details of the data collection,
structure solution, and refinement of 3d crystallizing
in the monoclinic space group P21/c are provided in the
observed for reported analogous molecules,
indi-
cating the absence of significant steric distortion around
the zirconocene moiety. Note that significantly shorter
Zr-O bond distances and larger O-Zr-O angles are
reported for [(Me3Si)2C5H3]ZrCl(OSiPh3)2 (1.921(4) and
1.929(5) Å, 102.17(19)°), in which the presence of strong

Group 4 Metallocene Containing Silsesquioxanes
Organometallics, Vol. 23, No. 24, 2004 5827
Table 2. Summary of Crystal Data, Collection
Data, and Refinement Details for 3d and 5d
3
d
5d
Crystal Data
Zr
formula
formula wt
cryst color
habit
C
50
H
84
O
12Si
8
C
50
H
84
O
8
12Si Hf
1193.11
1280.38
colorless
block
colorless
block
cryst size, mm
cryst syst
space group
a, Å
0.50 × 0.50 × 0.10
0.60 × 0.60 × 0.10
monoclinic
monoclinic
1
P2 /c
1
P2 /c
11.1457(2)
22.0030(5)
24.4973(6)
89.975(1)
6007.7(2)
4
11.1065(3)
22.0306(6)
24.441(1)
90.111(1)
5980.4(3)
4
b, Å
c, Å
â, deg
3
ς, Å
Z
-
3
D(calcd), g cm
µ(Mo KR), cm-
1.319
3.97
1.277
48.91
1
Intensity Measurements
diffractometer
radiation
Rigaku RAXIS-RAPID
graphite-monochromated
Mo KR (λ ) 0.710 69 Å)
detector aperture, mm
data image
ω oscillation range (κ )
270 × 256
270 × 256
74 exposure
130.0-190.0
4
5.0, Φ ) 0.0), deg
-
1
exposure rate, s deg
60.0
0.0-162.0
Figure 1. ORTEP drawing of 3d (50% probability thermal
ellipsoids). Cyclopentyl rings, except for ipso carbon atoms,
are omitted for clarity.
ω oscillation range (κ )
4
5.0, Φ ) 180.0), deg
-1
exposure rate, s deg
60.0
127.40
0.100
54.8
detector position, mm
pixel size, mm
2
θ
max, deg
55.0
no. of measd rflns
total
45 746
13 148
0.033
47 836
12 524
0.033
unique
R
int
Structure Solution and Refinement
direct methods (SIR92)
structure soln
no. of obsd rflns
no. of params refined
11 016 (I > 3.00σ(I)) 10 619 (I > 3.00σ(I))
724
724
a
R
0.047 (I > 3.00σ(I))
0.110 (I > 3.00σ(I))
3.35
0.042 (I > 3.00σ(I))
0.095 (I > 3.00σ(I))
2.36
a
R
w
GOF
max shift/error
peak in final diff map
0.00
0.01
-
3
max, e Å
0.85
-0.72
1.05
-1.14
min, e Å-
3
a
2
2 1/2
R ) ∑||Fo| - |Fc||/∑|Fo|; Rw ) [∑w(|Fo| - |Fc|) /∑wFo ]
.
Table 3. Selected Bond Distances (Å) for 3d and
5
d
Figure 2. ORTEP drawing of 5d (50% probability thermal
ellipsoids). Cyclopentyl rings, except for ipso carbon atoms,
are omitted for clarity.
3
d
5d
M(1)-O(1)
1.988(5)
1.986(5)
2.25
1.97(1)
1.98(1)
2.23
M(1)-O(4)
M(1)-Ct(C(36)-(40))
M(1)-Ct(C(41)-(45))
Si(1)-O(1)
2.26
2.24
The use of hafnocene dichloride in place of zirconocene
dichloride resulted in the formation of the hafnocene-
1.601(5)
1.603(5)
1.607(5)
1.631(6)
1.598(8)
1.602(8)
1.610(8)
1.619(8)
Si(3)-O(4)
containing silsesquioxane 5d. The 1H, C, and Si
13
29
Si(7)-O(12)
NMR spectra show its close structural resemblance to
that of the zirconium-containing derivative. The solid-
state structure of 5d (Figure 2) is almost identical with
that of 3d. The hafnium-oxygen bond distances (1.97-
Si(8)-O(12)
Table 4. Selected Bond Angles (deg) for 3d and 5d
3
d
5d
(1) and 1.98(1) Å) and O-Hf-O angle (97.7(6)°) are
O(1)-M(1)-O(4)
97.9(2)
106.3
97.7(6)
106.6
O(1)-M(1)-Ct(C(36)-(40))
O(1)-M(1)-Ct(C(41)-(45))
O(4)-M(1)-Ct(C(36)-(40))
O(4)-M(1)-Ct(C(41)-(45))
Ct-M(1)-Ct
slightly longer and acute compared with those of other
reported hafnium-containing silsesquioxanes and silox-
103.2
105.6
108.6
109.2
12
anes, i.e., Cp*Hf(c-C6H11)7Si7O12 (1.949(4) Å, 102.7(2)°)
106.3
106.4
and (Ph3SiO)2HfCl2‚THF (1.929(2) Å, 99.80(13)°),20 in-
dicating the presence of slight distortion, probably due
to the steric hindrance between the Cp groups and the
allyldimethylsilyl group.
127.7
127.4
Si(7)-O(12)-Si(8)
153.5(4)
153.7(6)
oxygen pπ-dπ donation of the siloxy ligand to the
zirconium center has been proposed. Such an effect is
considered to be not included in the present system.
9
b
(
20) Schweder, B.; G o¨ rls, H.; Walther, D. Inorg. Chim. Acta 1999,
286, 14.

5828 Organometallics, Vol. 23, No. 24, 2004
Wada et al.
As discussed above, direct monosilylation of the
forward and are easily affected by the slight changes
in reaction conditions and organic substituents (see
above).
silsesquioxane trisilanol 1a often results in poor selec-
tivity for the desired products. Therefore, an alternative
route for the synthesis of metallasilsesquoxanes bearing
a functional silyl group has been explored. The synthesis
of zirconocene-containing silsesquioxane monosilanol
was examined. Reaction of silsesquioxane trisilanol (1a)
and zirconocene dichloride in the presence of excess
triethylamine in THF at room temperature produced a
zirconocene-containing silsesquioxane monosilanol (3a)
in 38% yield and a zirconocene-bridged silsesquioxane
Further silylation or germylation of 3a was examined.
Because of the low stability of 3a, the reaction with
chlorodimethylsilane in the presence of amine was
carried out successively just after the preparation of 3a.
The desired product 3e was obtained in an isolated yield
of up to 70% by the reaction of 1a with zirconocene
dichloride at 0 °C for 3 h in THF immediately followed
by a reaction with chlorodimethylsilane at room tem-
perature for 18 h (eq 4). A small amount of 6 was also
(
6) as a byproduct in 24% yield (eq 3). The structure of
1
3
a was deduced from the H, 13C, and 29Si NMR spectra.
2
9
Namely, the Si NMR spectrum of 3a consists of five
peaks in a 1:1:2:1:2 ratio for seven silicon atoms in the
silsesquioxane cage, which are in agreement with the
local Cs symmetry of the siloxane framework, and one
of the peaks in the Si NMR spectrum was observed in
the particular range for silanol silicons, δ -56.35 ppm.
Unfortunately, 3a is not stable enough for complete
purification. According to the NMR spectra, 6 has been
determined to be a dimeric, Cs-symmetric molecule. In
produced as a byproduct. The characterization of 3e
revealed that it contains both a zirconocene group and
a dimethylsilyl substituent. The 29Si NMR spectrum
comprises five peaks in a 1:1:2:1:2 ratio for seven silicon
atoms in the silsesquioxane cage in the range of δ -64
to -68 ppm as well as a peak at δ -5.67 ppm, which is
assigned to the silicon atom of the dimethylsilyl group.
The synthesis of a silsesquioxane with a germyl group
adjacent to the zirconocene moiety was examined, since
it has been reported that the introduction of a germa-
nium species onto the titanium-silica catalysts en-
hances their activities for the epoxidation of olefins.21
By the successive in situ treatment of 3a with trimeth-
ylgermanium bromide, a silsesquioxane including a
trimethylgermanium group adjacent to the zirconocene
moiety (3f) was obtained in 70% isolated yield. A
silsesquioxane containing both hafnocene and dimeth-
ylsilyl groups, 5e, was synthesized in a similar manner
in 77% isolated yield. In this case, the hafnocene-
containing silsesquioxane monosilanol 5a would be
2
9
1
13
the H and C NMR spectra there are three sets of
resonances of the cyclopentadienyl rings. Two cyclopen-
tadienyl rings are located on the bridging zirconium, two
in exo positions with regard to the bridging zirconocene,
and two in endo positions. A silsesquioxane monosilanol
similar to 3a has been suggested as an intermediate in
the reaction of Cp[Me2(EtO)SiC5Me4]ZrCl2 with 1a.9
c
However, such a compound has not been isolated and
characterized, and the final product is an intractable
polymeric species.9 Our present results also are in
c
1
0b
contrast to the work reported by Buys et al. In their
work the reaction of a silsesquioxane triol, (c-C6H11)7-
Si7O9(OH)3, with zirconocene or hafnocene dichloride in
the presence of excess bases resulted in the complete
loss of both Cp ligands and produced an oligomeric
species, i.e., {M3[(c-C6H11)7Si7O12]4Cl}H (M ) Zr, Hf).1
Again, this suggests that the reactions of metallocene
dichlorides with silsesquioxane silanols are not straight-
1
formed as an intermediate, as suggested by the H NMR
observation of the reaction mixture.
0b
(
21) (a) Oldroyd, R. D.; Thomas, J. M.; Sankar, G. Chem. Commun.
997, 2025. (b) Oldroyd, R. D.; Sankar, G.; Thomas, J. M.; Szkaya, D.
J. Phys. Chem. B 1998, 102, 1849.
1

Group 4 Metallocene Containing Silsesquioxanes
Organometallics, Vol. 23, No. 24, 2004 5829
Treatment of the zirconocene-containing silsesquiox-
ane 3e with 2 equiv of hydrogen chloride in toluene
almost quantitatively gives the dimethylsilyl group
containing silsesquioxane disilanol 1e and zirconocene
dichloride (eq 5). The NMR spectra of 1e indicate local
CH2Si- connections, together with a trace amount of
byproducts including branched -SiCH(CH3)Si- con-
nections (2g′ and 3g′). Attempts at the preparation of
heterogeneous catalysts by immobilization of 2g or 3g
onto other porous materials, such as mesoporous silicas,
are now in progress, and the results will be reported in
due course.
Catalytic Activity of Group 4 Metal Containing
Silsesquioxanes toward the Epoxidation of Cyclo-
hexene. The catalytic activities of titanium-containing
oligosilsesquioxanes for the epoxidation of olefins have
been examined from the viewpoint of a soluble analogue
of titanosilicates.6
d,e,8
Crocker and Orpen have compared
the catalytic activity of bipodal (with two Si-O-Ti
bondings around the Ti atom), tripodal (with three Si-
O-Ti bondings), and tetrapodal (with four Si-O-Ti
bondings) titanium-containing silsesquioxanes toward
the olefin epoxidation and reported that the tripodal
i
molecule (c-C5H9)7Si7O12Ti(O Pr) is far more reactive
than the others by an order of magnitude.8c Now we
have compared the catalytic activity of newly synthe-
sized bipodal titanocene-containing silsesquioxanes for
the epoxidation of cyclohexene with tripodal CpTi[(c-
C5H9)7Si7O12] (7),8a one of the most active silsesqui-
Cs symmetry of the siloxane backbone and the presence
of two silanol groups. In the Si NMR spectrum, there
is a peak in the particular range for silanol groups at
2
9
oxane-based catalysts, and tetrapodal Ti[(c-C5H9)7Si7O11-
c
(
OSiMe3)]2 (8b).8 The results are shown in Table 1. The
-
56.35 ppm. In the present case the zirconocene moiety
reaction using 1.0 mol % of 2b at 50 °C for 4 h with
BuOOH as an oxidating reagent selectively gives cy-
acts as a protecting group for disilanols. This method
provides an alternative route for functionalized disil-
anols, while the selective synthesis of 1e via direct
silylation of 1a is very difficult (see above),
t
clohexene oxide in 22% yields. As byproducts, trace
amounts of cyclohexanone and cyclohexanol were also
produced. When the reaction was longer than 4 h, the
gradual formation of intractable high-molecular-weight
species was observed, while the amounts of such prod-
ucts were very small within 4 h. Similar to the case
reported by Crocker and Orpen, the catalytic activity
decreased in the following order: tripodal 7 > bipodal
The synthesis of silsesquioxanes including ethoxysilyl
groups was examined by utilizing hydrosilylative reac-
tions. Our initial attempts at the hydrosilylation of
ethoxysilanes bearing olefinic groups by 1e, 3e, and 5e
using platinum catalysts were, however, unsuccessful.
In all cases examined, only the starting materials were
recovered. This is probably caused by the steric hin-
drance around the -Si(H)Me2 groups. On the other
hand, the reactions of 2c and 3c with an excess amount
of HSiMe2(OEt) in the presence of the Pt catalyst
quantitatively yield the desired titanocene- and zir-
conocene-containing silsesquioxanes bearing an ethoxy-
silyl group, respectively. The main products from 2c and
2
b > tetrapodal 8b. Remarkably, silsesquioxanes with
alkenylsilyl groups, 2c,d, show higher activity than 2b.
Acceleration of the reaction by the presence of alkenyl-
silyl groups is much more remarkable with tetrapodal
titanium silsesquioxanes. The yield of the epoxide in the
presence of 8d bearing two allyldimethylsilyl groups is
almost double the yield with 8b, and at 60 °C the yield
increased to 64%. The exact reasons that the presence
of alkenylsilyl groups enhances the catalytic activity are
still unclear, and a more detailed study on the promo-
tional effect of these substituents is now in progress.
11b
3
c were 2g and 3g, the products with linear -SiCH2-
Concluding Remarks
A series of new group 4 metallocene containing
silsesquioxanes including functionalized silyl groups
have been synthesized in excellent yields. The successful
synthesis of titanocene-containing molecules, 2b-d, will
fill in the blanks in a series of titanosilsesquioxanes
bearing cyclopentadienyl-type ligands. New zirconocene-
or hafnocene-containing silsesquioxanes, which are
expected to be appropriate model compounds for the
mechanistic studies and as potential catalyst precursors
of industrially important silica-supported metallocenes,
have been synthesized. The present study also gives an
alternative route for the synthesis of silsesquioxanes
bearing functionalized silyl groups that cannot be
prepared by direct silylation. It has been demonstrated
that the zirconocene moiety can act as a protecting

5830 Organometallics, Vol. 23, No. 24, 2004
Wada et al.
group for disilanols. The reaction of zirconocene-
containing molecules with 2 equiv of hydrogen chloride
resulted in the clean formation of functionalized disil-
anols. The thus-introduced functional silyl groups are
useful for further transformation into other functional
groups, such as an ethoxysilyl group, or for the prepara-
tion of polymeric materials and immobilized heteroge-
neous catalysts. As shown in the earlier reports, cyclo-
pentadienyltitanium siloxane compounds can be excellent
homogeneous catalysts for the epoxidation of alkenes.8a
In the present study, titanocene-containing molecules
from recrystallization by slow diffusion of acetonitrile into a
toluene solution. Yield: 81%. Mp: 129 °C dec. H NMR (400
1
MHz, C
m, 56 H), 1.24-1.19 (br m, 7H), 0.10 (s, 9H). C{ H} NMR
75 MHz, CDCl , 25 °C): δ 117.75, 116.97 (C ), 28.83, 28.68,
8.59, 28.40, 28.35, 28.32, 28.23, 27.96, 27.80, 27.72, 27.69,
7.65, 27.49 (CH ), 25.53, 24.71, 24.26, 24.39, 23.46 (1:2:2:1:1
6 6
D , 25 °C): δ 6.29 (s, 5H), 6.03 (s, 5H), 1.98-1.54 (br
1
3
1
(
3
5 5
H
2
2
2
29
1
for CH), 2.26 (Si(CH
M Cr(acac) , 25 °C): δ 7.54, -64.47, -65.08, -66.05, -67.21
(1:1:3:1:2). MS (FAB): m/z 1057 [M -C H ] , 988 [M - C H
5
3 3 3
) ). Si{ H} NMR (76 MHz, CDCl , 0.02
3
+
5
5
5
+
- C
5 9
H ] . IR spectrum (KBr): 2954 (s), 2913 (sh), 2872 (s),
1636 (w), 1450 (m), 1255 (m), 1111 (vs), 1013 (sh), 946 (sh),
-1
915 (m), 861 (m), 848 (m), 817 (w), 755 (m), 498 (m) cm . Anal.
(2b-d) are found to show moderate catalytic activities.
Calcd for C48 Ti (1123.74): C, 51.30; H, 7.36. Found:
82 8
H O12Si
An unexpected effect of alkenylsilyl groups of improving
the catalytic activities has been found in the present
study. This phenomenon is also recognized in the case
of tetrapodal titanium silsesquioxanes 8b-d, implying
its generality. An extensive study on the exploration of
the functionality and further transformation of these
silsesquioxanes will be reported in due course.
C, 51.06; H, 7.17.
2 5 9 7 7 2 2
Synthesis of Cp Ti[(c-C H ) Si O11](OSiMe CHdCH )
2c). A method similar to that for 2b was adopted by using 1c
(
(
960 mg, 1.0 mmol) instead of 1b. Yellow microcrystals.
1
Yield: 81%. Mp: 172 °C dec. H NMR (300 MHz, C
6
D
6
, 25
3
3
°
1
)
1
6
C): δ 6.28 (s, 5H), 6.18 (dd JHH(trans) ) 20.2 Hz, JHH(cis) )
3
2
4.9 Hz, 1H), 6.03 (s, 5H), 5.86 (dd, JHH(cis) ) 14.9 Hz, JHH
3
2
3.7 Hz, 1H), 5.72 (dd, JHH(trans) ) 20.0 Hz, JHH ) 3.9 Hz,
H), 1.99-1.55 (br m, 56 H), 1.26-1.16 (br m, 7H), 0.15 (s,
Experimental Section
1
3
1
6 6
H). C{ H} NMR (75 MHz, C D , 25 °C): δ 139.57 (Si-
Materials and Methods. All reactions and subsequent
manipulations were carried out under anaerobic and anhy-
drous conditions under either high vacuum or an atmosphere
of argon using standard Schlenk techniques. Organic solvents
and triethylamine were dried and distilled under argon with
appropriate drying agents (sodium, calcium chloride, calcium
hydride) just before use. Dehydrated acetone and acetonitrile
were purchased from Kanto Chemical Co. Inc. and used as
received. Titanocene dichloride and zirconocene dichloride
2 2 5 5
CHdCH ), 131.80 (SiCHdCH ), 117.80, 116.96 (C H ), 28.85,
28.69, 28.56, 28.40, 28.34, 28.24, 27.98, 27.82, 27.73, 27.70,
27.67, 27.50 (CH ), 25.48, 24.73, 24.26, 23.50, 23.47 (1:2:2:1:1
2
for CH), 0.65 (Si(CH ) ). 29Si{
1
3
2
H} NMR (76 MHz, CDCl , 0.02
3
M Cr(acac) , 25 °C): δ -3.51, -64.47, -65.08, -65.88, -67.18
3
+
5
5
5 5
(1:1:3:1:2). MS (FAB): m/z 1069 [M - C H ] , 1000 [M - C H
22
+
5 9
- C H ] . IR spectrum (KBr): 3052 (vw), 2949 (s), 2913 (sh),
2867 (s), 1631 (w), 1451 (m), 1409 (w), 1250 (m), 1106 (vs),
1008 (sh), 951 (sh), 910 (m), 822 (m), 802 (m), 786 (m), 719
(
Wako Pure Chemical Industries, Ltd.) and bis(pentamethyl-
(m), 493 (m) cm-1. Anal. Calcd for C H O Si Ti (1135.75):
4
9
82 12
8
cyclopentadienyl)zirconium dichloride, hafnocene dichloride,
chlorodimethylsilane, chlorotrimethylsilane, trimethylgerma-
nium bromide, hydrogen chloride in diethyl ether solution (1.0
M), and 1,3,5,7,9,11,14-heptacyclopentyltricyclo[7.3.3.15,11]-
heptasiloxane-endo-3,7,14-triol (1a) (Aldrich) were obtained
C, 51.82; H, 7.28. Found: C, 51.48; H, 7.74.
Synthesis of Cp Ti[(c-C Si 11](OSiMe
CH ) (2d). A method similar to that for 2b was adopted by
using 1d (974 mg, 1.0 mmol) instead of 1b. Yellow microcrys-
2
5
H
9
)
7
7
O
2 2
CH CHd
2
1
3
tals. Yield: 75%. Mp: 146 °C dec. H NMR (300 MHz, CDCl ,
commercially and used without further purification. (c-C
5
11b
H
9
)
7
-
3
2
1
5 °C): δ 6.27 (s, 5H), 6.02 (s, 5H), 5.83 (tdd, JHH ) 8.0, 10.8,
2
3
Si
7
O
9
(OH)
2
(OSiMe
2
R) (1b, R ) methyl; 1c, R ) vinyl; 1d,
Zr[(c-C Si 11(OSiMe R)] (3b, R ) methyl;
CpTi[(c-C Si 12] (7),
11(OSiMe R)] (8b, R ) methyl; 8c, R ) vinyl;
d, R ) allyl ) were synthesized on the basis of the methods
3
3
6.4 Hz, 1H), 4.93 ( JHH ) 10.8 Hz, 1H), 4.92 (d, JHH ) 16.4
Hz, 1H), 2.11-1.45 (br m, 56 H), 1.57 (d, JHH ) 8.0 Hz, 2H),
.24-1.13 (br m, 7H), 0.11 (s, 6H). C{ H} NMR (75 MHz,
CDCl , 25 °C): δ 134.63 (SiCH CHdCH ), 117.73, 117.00
), 113.69 (SiCH CHdCH ), 28.84, 28.68, 28.59, 28.40,
8.32, 28.23, 27.98, 27.80, 27.72, 27.69, 27.66, 27.49 (CH ),
6.61 (SiCH CHdCH ), 25.47, 24.71, 24.26, 23.46 (1:2:2:2 for
19
R ) allyl ), Cp
2
5
H
)
9 7
7
O
2
3
1
1b
8a,14b
3
C
c, R ) vinyl),
Si
5
H
9
)
7
7
O
and Ti[(c-
13
1
1
8
c
19
5
H
9
)
7
7
O
2
2
3
2
2
1
9
8
(C
5
H
5
2
2
described in previous reports by us or other researchers.
Physical and Analytical Measurements. Solution-phase
NMR spectra were recorded on JEOL JNM-AL-300 and JEOL
2
2
2
2
2
29
1
CH), 0.15 (Si(CH
3
)
2
). Si{ H} NMR (76 MHz, CDCl
3
, 0.02 M
1
13
JNM-EX-400 instruments. H and C spectra were referenced
to internal solvent resonances and reported relative to SiMe
Cr(acac)
3
, 25 °C): δ 4.79, -64.49, -65.11, -66.12, -67.16
.
+
4
(
-
2
9
1:1:3:1:2). MS (FAB): m/z 1083 [M - C
H
] , 1014 [M - C
5 5
H
5
5
2
9
Chemical shifts for the Si nuclei were referenced to the
resonance of external SiMe . Fast atom bombardment (FAB)
+
C H ] . IR spectrum (KBr): 3078 (vw), 2949 (s), 2913 (sh),
5 9
4
867 (s), 1631 (w), 1451 (m), 1255 (m), 1106 (vs), 1008 (sh),
46 (m), 915 (m), 848 (m), 807 (m), 735 (m), 498 (m) cm . Anal.
Ti (1149.77): C, 52.23; H, 7.36. Found:
mass spectra were recorded using a JEOL SX-102A mass
spectrometer. Elemental analyses were performed at the
Microanalytical Center of Kyoto University. The oxidation
products were analyzed by GC-MS (Shimadzu QP 5000,
CBP10-S25-050 capillary column, i.d. 0.33 mm, length 25 m,
o.d. 0.43 mm at 323∼473 K) and gas chromatography (SE-30,
i.d. 3.0 mm, length 3.0 m at 323∼473 K).
-1
Calcd for C50
C, 51.93; H, 7.92.
Synthesis of Cp
CH ) (3d). In a typical experiment, to a solution of 1d (974
mg, 1.0 mmol) and Cp ZrCl (292 mg, 1.0 mmol) in CHCl (50
cm ) was added triethylamine (1.4 cm , 10 mmol) dropwise and
and the mixture was stirred at room temperature for 60 min.
The solvent was then evaporated at room temperature to leave
84 8
H O12Si
2 5 9 7 7 2 2
Zr[(c-C H ) Si O11](OSiMe CH CHd
2
2
2
2
3
3
2 5 9 7 7 3
Synthesis of Cp Ti[(c-C H ) Si O11](OSiMe ) (2b). In a
typical experiment, to a solution of 1b (947 mg, 1.0 mmol) and
3
2
Cp TiCl
2
(249 mg, 1.0 mmol) in toluene (50 cm ) was added
3
an off-white solid. This was extracted with hexane (60 cm ) to
3
triethylamine (0.3 cm , 2.17 mmol) dropwise at room temper-
ature, and the mixture was stirred for 72 h. The solution
turned yellow. After filtration, the clear filtrate was evapo-
rated. Yellow microcrystals of the product 2b were obtained
give a clear filtrate and a white residue of triethylammonium
chloride. The filtrate was evaporated, and the product 3d was
obtained from recrystallization by slow diffusion of acetone into
1
a CHCl
MHz, CDCl
.78 (m, 1H), 4.74 (m, 1H), 1.79-1.51 (br m, 56 H), 1.42 (d,
3
solution. Yield: 70%. Mp: 170 °C dec. H NMR (300
3
, 25 °C): δ 6.34 (s, 5H), 6.19 (s, 5H), 5.69 (m, 1H),
(
22) Perrin, D. D.; Armarego, W. L. F. Purification of Laboratory
Chemicals, 3rd ed.; Pergamon: Oxford, U.K., 1988.
23) Abbenhuis, H. C. L.; Burrows, A. D.; Kooijman, H.; Lutz, M.;
Palmer, M. T.; van Santen, R. A.; Spek, A. L. Chem. Commun. 1998,
627.
4
3
13
J
HH ) 8.2 Hz, 2H), 0.97-0.91 (br m, 7H), -0.05 (s, 6H). C-
(
1
{
3 2 2
H} NMR (75 MHz, CDCl , 25 °C): δ 134.63 (SiCH CHdCH ),
2
113.95, 113.22 (C ), 113.03 (SiCH
5
H
5
2
CHdCH ), 27.99, 27.85,
2

Group 4 Metallocene Containing Silsesquioxanes
Organometallics, Vol. 23, No. 24, 2004 5831
1
2
2
2
7.81, 27.68, 27.58, 27.51, 27.47, 27.33, 27.20, 27.09, 27.06,
6.90 (CH ), 26.64 (SiCH CHdCH ), 24.86, 23.57, 23.50, 22.72,
268 (2:1:1:2:1 for CH), -0.37 (Si(CH
, 0.02 M Cr(acac) , 25 °C): δ 4.75, -65.22, -65.71,
66.23, -66.28, -67.66 (1:1:2:1:1:2). MS (FAB): m/z 1193 [M
6: mp >300 °C; H NMR (300 MHz, C
6
D
6
, 25 °C) δ 6.41 (s,
2
2
2
10H), 6.25 (s, 10H), 6.20 (s, 10H) 2.36-1.50 (br m, 112H),
2
9
1
13
)
3 3
). Si{ H} NMR (76
1.50-1.11 (br m, 14H); C NMR (75 MHz, CDCl
114.26, 113.89, 113.83 (C ), 31.92, 30.19, 29.30, 28.64, 28.41,
28.29, 28.20, 28.11, 27.85, 27.68, 27.55, 27.35, 26.93 (CH of
Cy), 27.17, 24.19, 24.02, 23.48, 23.29 (1:2:2:1:1 for ipso-CH of
3
, 25 °C) δ
MHz, CDCl
3
3
5 5
H
-
+
2
+
+
5 5
H] , 1127 [M - C H ] . IR spectrum (KBr): 3073 (vw), 2949
2
9
(s), 2913 (sh), 2862 (s), 1631 (w), 1451 (m), 1255 (m), 1100 (vs),
3 3
Cy); Si NMR (76 MHz, CDCl , 0.02 M Cr(acac) , 25 °C) δ
1
008 (sh), 951 (m), 910 (m), 843 (m), 817 (sh), 802 (s), 488 (m)
-63.47, -65.07, -65.44, -65.93, -67.12 (1:1:2:1:2); IR spec-
trum (KBr) 3109 (w), 2949 (s), 2862 (s), 1631 (w), 1451 (m),
1245 (m), 1121 (vs), 1095 (sh), 1018 (s), 967 (s), 807 (m), 730
-
1
cm . Anal. Calcd for C50
.10. Found: C, 50.35; H, 6.89.
Synthesis of Cp* Zr[(c-C
CHdCH ) (4d). A method similar to that for 3d was adopted
84 8
H O12Si Zr (1193.11): C, 50.33; H,
7
-
1
H
9
)
7
Si
7
O
11](OSiMe
2
CH
2
-
(m), 663 (w), 488 (m) cm . Anal. Calcd for C100
(2409.19): C, 49.86; H, 6.53. Found: C, 50.06; H, 6.77.
Synthesis of Cp Zr[(c-C Si 11](OSiMe H) (3e) via
156 3
H O24Si14Zr
2
5
2
by using 433 mg (1.0 mol) of (pentamethylcyclopentadienyl)-
zirconium dichloride in place of zirconocene dichloride. Yield:
2
5
H
9
)
7
7
O
2
3
3
3a. Triethylamine (1.0 cm , 7.2 mmol) in THF (15 cm ) was
added dropwise to a solution of the silsesquioxane trisilanol
1
56%. Mp: 110 °C dec. H NMR (300 MHz, CDCl
3
, 25 °C): δ
3
5
.77 (tdd, JHH ) 8.2, 10.1, 15.8 Hz, 1H), 4.83 (m, 1H), 4.80
5 9 7 7 9 3
(c-C H ) Si O (OH) (1a; 876 mg, 1.0 mmol) and zirconocene
3
(
m, 1H), 2.00 (s, 15H), 1.94 (s, 15H), 1.78-1.43 (br m, 56H),
.57 (d, JHH ) 8.2 Hz, 2H), 1.03-0.83 (br m, 7H), 0.08 (s, 6H).
dichloride (351 mg, 1.2 mmol) in THF (80 cm ), and the
mixture was stirred at 0 °C for 3 h. To this reaction mixture
3
1
13
1
3
C{ H} NMR (75 MHz, CDCl
3
, 25 °C): δ 134.54 (SiCH
), 113.23 (SiCH CHdCH ), 121.19
), 28.46, 28.37, 28.00, 27.71, 27.65,
7.56, 27.53, 27.20, 27.14, 27.11, 27.08, 26.98, 26.77 (CH ),
6.30 (SiCH CHdCH ), 26.98, 25.24, 23.67, 23.37, 22.81
Me ), -0.06 (Si(CH ).
, 0.02 M Cr(acac) , 25 °C): δ
.74, -64.53, -65.59, -66.40, -66.70, -67.39 (1:1:2:1:1:2). IR
spectrum (KBr): 3083 (vw), 2955 (s), 2913 (sh), 2867 (s), 1631
2
CHd
was added chlorodimethylsilane (0.34 cm , 3.0 mmol) in THF
3
CH
2
), 121.16, 120.30 (C
Me
5 5
2
2
(15 cm ) dropwise and the mixture was stirred at room
(
C
5
Me ), 120.29 (C Me
5
5
5
temperature for 18 h. After filtration, the resulting clear
solution was evaporated in vacuo to give a pale yellow solid.
2
2
2
3
2
2
The solid was extracted with benzene (20 cm ) to give a clear
3
(
2:1:2:1:1 for CH), 11.98, 11.54 (C
5
5
3
)
2
filtrate. To the filtrate was added acetone (50 cm ), and the
2
9
1
Si{ H} NMR (76 MHz, CDCl
3
3
precipitate that formed was filtered off. The resulting clear
3
3
solution was evaporated, and benzene (15 cm ) was added. The
product was obtained by slow diffusion of acetonitrile into a
1
(
w), 1451 (m), 1384 (w), 1255 (m), 1100 (vs), 997 (m), 945 (m),
benzene solution. Yield: 70%. Mp: 297-298 °C. H NMR (300
-
1
3
5
03 (m) cm . Anal. Calcd for C60
4.05; H, 7.86. Found: C, 53.93; H, 7.86.
Synthesis of Cp Hf[(c-C Si
CHdCH ) (5d). A method similar to that for 3d was adopted
H
104
O
12Si
8
Zr (1333.39): C,
MHz, C
6
D
6
, 25 °C): δ 6.36 (s, 5H), 6.15 (s, 5H), 5.22 (sept, JHH
5
) 2.9 Hz, 1H), 2.18∼1.47 (br m, 56H), 1.32∼1.10 (br m, 7H),
0.46 (d, JHH ) 2.9 Hz, 6H). C NMR (75 MHz, C , 25 °C):
δ 114.42, 113.69 (C ), 28.59, 28.44, 28.33, 28.23, 28.13, 28.04,
27.85, 27.80, 27.68, 27.52, 27.43, 27.34 (CH of Cy), 25.11,
24.12, 24.03, 23.32, 23.21 (1:2:2:1:1 for ipso-CH of Cy), 1.05
3
13
H
9
)
7
7
O
11](OSiMe
2
CH
2
-
6 6
D
2
5
5 5
H
2
by using 380 mg (1.0 mol) of hafnocene dichloride in place of
2
1
zirconocene dichloride. Yield: 69%. Mp: 168-169 °C. H NMR
2
9
(
(
300 MHz, CDCl
tdd, JHH ) 8.0, 10.0, 15.6 Hz, 1H), 4.76 ( JHH ) 10.0 Hz, 1H),
3
, 25 °C): δ 6.29 (s, 5H), 6.14 (s, 5H), 5.70
3 2 6 6 3
(Si(CH ) H). Si NMR (76 MHz, C D , 0.02 M Cr(acac) , 25
3
3
°C): δ -5.67, -64.85, -65.39, -65.52, -66.01, -67.51 (1:1:1:
2:1:2). IR spectrum (KBr): 2949 (s), 2862 (s), 2130 (w), 1724
(sh), 1585 (m), 1456 (m), 1255 (m), 1106 (vs), 946 (m), 848 (m),
3
4
.86 (d, JHH ) 15.6 Hz, 1H), 1.79-1.39 (br m, 56H), 1.41 (d,
3
13
J
HH ) 8.0 Hz, 2H), 1.05-0.90 (br m, 7H), -0.06 (s, 6H). C-
1
-1
{
H} NMR (75 MHz, CDCl
13.01 (SiCH CHdCH ), 112.72, 112.13 (C
7.80, 27.68, 27.58, 27.50, 27.47, 27.34, 27.21, 27.09, 27.06,
7.02, 26.89 (CH ), 26.03 (SiCH CHdCH ), 24.84, 23.55, 22.67
3
, 25 °C): δ 134.61 (SiCH
2
CHdCH
2
),
802 (m), 740 (m), 493 (m) cm . MS (FAB): m/z 1151 [M -
+
+
1
2
2
2
2
5
H
5
), 27.95, 27.84,
H] , 1085 [M - H - C
(1153.05): C, 48.96; H, 6.99. Found: C, 48.95; H, 7.24.
Synthesis of Cp Zr[(c-C H ) Si O ](OGeMe ) (3f) via
5 5 80 8
H ] . Anal. Calcd for C47H O12Si Zr
2
2
2
2
5
9
7
7
11
3
2
9
1
(
1:4:2 for CH), -0.39 (Si(CH
CDCl , 0.02 M Cr(acac) , 25 °C): δ 4.73, -64.09, -65.10,
66.13, -66.33, -67.66 (1:2:1:1:1:2). IR spectrum (KBr): 3073
3
)
3
). Si{ H} NMR (76 MHz,
3a. A method similar to that for 3e was adopted by using
3
3
3
trimethylgermanium bromide (0.51 cm , 4.0 mmol) in THF (10
3
-
cm ) in place of chlorodimethylsilane. Yield: 70%. Mp: 197-
1
(
vw), 2944 (s), 2908 (sh), 2862 (s), 1631 (w), 1456 (m), 1255
m), 1106 (vs), 1023 (sh), 967 (m), 910 (m), 848 (m), 822 (m),
198 °C. H NMR (300 MHz, C D CD , 25 °C): δ 6.33 (s, 5H),
6
5
3
(
6.12 (s, 5H), 2.34-1.36 (br m, 56H), 1.29-1.11 (br m,7H), 0.30
-
1
13
8
02 (s), 493 (m) cm . Anal. Calcd for C50
H
84
O12Si
8
Hf
(s, 9H). C NMR (75 MHz, C D CD , 25 °C): δ 114.48, 113.67
6
5
3
(
1280.38): C, 46.90; H, 6.61. Found: C, 46.30; H, 6.58.
Synthesis of Cp Zr[(c-C Si 11](OH) (3a). To a solu-
tion of silsesquioxane trisilanol (c-C Si (OH) (1a; 438
mg, 0.50 mmol) and zirconocene dichloride (176 mg, 0.60 mmol)
5 5
(C H ), 28.79, 28.66, 28.47, 28.39, 28.30, 28.16, 28.11, 27.85,
2
H )
5 9 7
7
O
5
27.71, 27.62, 27.59, 27.41 (CH
2
of Cy), 26.13, 24.35, 24.22,
).
6 5 3 3
Si NMR (76 MHz, C D CD , 0.02 M Cr(acac) , 25 °C): δ
H
)
9 7
7
O
9
3
23.38, 23.35 (1:2:2:1:1 for ipso-CH of Cy), 2.98 (Ge(CH )
3 3
2
9
3
3
in THF (70 cm ) was added triethylamine (1.0 cm , 7.2 mmol)
in THF (15 cm ) dropwise, and the mixture was stirred at room
temperature for 18 h. The triethylammonium chloride that
deposited was filtered off, and the filtrate was evaporated in
vacuo to give a white solid. Hexane was added, the mixture
was stirred, and an insoluble white precipitate was recovered
by filtration. Reprecipitation by diffusion of acetone into
benzene solution gave a white powder of Cp
Si (6) in a yield of 24%. The supernatant was evaporated
under reduced pressure and gave a white powder of 3a.
Yield: 38% (crude).
-63.94, -64.95, -65.64, -66.01, -67.95 (1:1:2:1:2). IR spec-
trum (KBr): 3119 (vw), 2954 (s), 2862 (s), 1450 (m), 1265 (sh),
1244 (m), 1105 (vs), 1017 (sh), 956 (sh), 801 (s), 616 (m), 492
3
-
1
+
(m) cm . MS (FAB): m/z 1145 [M - C
5 5
H ] . Anal. Calcd for
48 82 7
C H O12Si
GeZr (1211.60): C, 47.58; H, 6.82. Found: C,
47.74; H, 6.55.
Synthesis of Cp Hf[(c-C H ) Si O ](OSiMe H) (5e) via
2
5
9
7
7
11
2
2 2 5 9 7
Zr[Cp Zr(c-C H ) -
2 5 9 7 7 11
Cp Hf[(c-C H ) Si O ](OH) (5a). A method similar to that
7
O ]
12 2
for 3e was adopted by using hafnocene dichloride (457 mg, 1.2
3
mmol) in THF (70 cm ) in place of zirconocene dichloride. The
intermediate 5a has not been isolated. Yield: 77%. Mp: 243-
a: 1H NMR (300 MHz, CDCl
, 25 °C) δ 6.37 (s, 5H), 6.20
244 °C. H NMR (300 MHz, C
1
D
, 25 °C): δ 6.32 (s, 5H), 6.11
HH ) 2.9 Hz, 1H), 2.18∼1.46 (br m,
56H),1.32∼1.11 (br m, 7H), 0.20 (d, JHH ) 2.9 Hz, 6H).
NMR (75 MHz, C , 25 °C): δ 113.19, 112.58 (C ), 28.56,
28.42, 28.33, 28.23, 28.17, 28.04, 27.82, 27.68, 27.55, 27.51,
27.35 (CH of Cy), 25.10, 24.19, 24.03, 23.29, 23.21 (1:2:2:1:1
for ipso-CH of Cy), 0.81 (Si(CH
0.02 M Cr(acac) , 25 °C): δ -5.71, -63.82, -64.80, -65.39,
3
3
6
6
13
3
(
(
2
2
1
s, 5H), 1.89-1.34 (br m, 56H), 1.07-0.84 (br m, 7H); C NMR
75 MHz, CDCl , 25 °C) δ 113.88, 113.33 (C ), 27.93, 27.82,
7.64, 27.53, 27.50, 27.36, 27.25, 27.16, 27.12, 27.10, 27.03,
7.00, 26.95 (CH of Cy), 23.52, 23.37, 23.20, 22.74, 22.46 (2:
:2:1:1 for ipso-CH of Cy); Si NMR (76 MHz, CDCl
, 25 °C) δ -56.35, -65.12, -65.54, -66.43, -67.56
1:1:2:1:2).
(s, 5H), 5.05 (sept., J
3
13
3
5
H
5
C
D
6 6
5 5
H
2
2
9
3
, 0.02 M
2
2
9
Cr(acac)
(
3
3 2 6 6
) H). Si NMR (76 MHz, C D ,
3

5832 Organometallics, Vol. 23, No. 24, 2004
Wada et al.
-
65.84, -67.46 (1:2:1:1:1:2). IR spectrum (KBr): 2939 (s), 2867
Hz, 3H, OCH
(s, 6H, both Si(CH
δ 114.43, 113.71 (C
28.30, 28.22, 28.11, 28.08, 27.82, 27.69, 27.54, 27.35 (CH
25.58, 24.17, 24.10, 23.29 (1:2:2:2 for CH), 18.94 (OCH CH
9.86, 8.15 (Si(CH Si), -0.22, -2.48 (Si(CH
2
CH
3
), 0.61 (s, 4H, Si(CH
2
)
2
Si), 0.20 (s, 6H), 0.18
1
3
1
(
(
(
s), 2130 (w), 1718 (sh), 1605 (m), 1445 (m), 1250 (m), 1095
3
)
2
); C{ H} NMR (75 MHz, CDCl
3
, 25 °C)
-
1
vs), 977 (m), 848 (m), 797 (m), 730 (m), 493 (m) cm . MS
FAB): m/z 1239 [M - H] , 1175 [M - C
5
H
5
), 58.24 (OCH CH ), 28.59, 28.53, 28.43,
2
3
+
+
5
H
5
] . Anal. Calcd for
2
),
),
C
47
H
80
O
12Si
8
Hf (1240.32): C, 45.51; H, 6.50. Found: C, 45.26;
2
3
H, 6.24.
Synthesis of (c-C
Hydrogen chloride solution (1 M in Et
was added to a solution of 3e (576 mg, 0.50 mmol) in toluene
2
)
2
3
)
2
); IR spectrum
5
H
9
)
7
Si
7
O
9
(OH)
2
(OSiMe
2
2
H) (1e) via 3e.
(KBr) 2949 (s), 2867 (s), 1455 (m), 1259 (m), 1104 (vs), 1007
3
-1
O, 1.0 cm , 1.0 mmol)
(sh), 956 (m), 907 (sh), 791 (s), 729 (sh), 491 (m) cm .
Catalytic Epoxidation of Cyclohexene. All the reactions
were performed by the use of hot stirrers equipped with cooling
blocks for refluxing the solution. The appropriate catalyst
(0.033 mmol as M) and cyclohexene (3.3 mmol) in toluene
3
(
15 cm ), and the mixture was stirred at room temperature
for 18 h. After the solvent was evaporated, the resulting white
solid was extracted with hexane (20 cm ). An almost quantita-
3
3
tive yield of zirconocene dichloride (>95%) was obtained as a
hexane-insoluble solid. The filtrate was evaporated, and the
product was obtained almost quantitatively (>95%). The
solution (1.5 cm ) were taken into a glass Schlenk tube under
an Ar atmosphere. The reaction mixture was heated by the
heating block and allowed to equilibrate at 50 or 60 °C for 10
1
t
3
isolated product 1e is unstable for the microanalysis. H NMR
min. BuOOH (3.3 mmol) in decane solution (5.5 M, 0.6 cm )
was then added by the use of a plastic pipet. The mixture was
stirred for 4 h and then cooled rapidly in an ice bath. The
products were identified by the use of GC-MS and quantified
by GC analyses using biphenyl as an internal standard.
X-ray Crystallographic Study of 3d and 5d. Colorless
single crystals of 3d and 5d suitable for analysis by X-ray
diffraction were provided from recrystallization by slow dif-
fusion of acetonitrile into mesitylene solutions. All measure-
ments were made on a Rigaku RAXIS imaging plate area
detector with graphite-monochromated Mo KR radiation (λ )
0.710 69 Å). All calculations were performed using the Crystal
Structure crystallographic software package. The structures
3
(
(
(
300 MHz, C
6
D
6
, 25 °C): δ 5.09 (sept, J ) 2.8 Hz, 1H), 4.55
br s, 2H), 2.12-1.46 (br m, 56H), 1.32-1.10 (br m,7H), 0.39
3
13
d, J ) 2.8 Hz, 6H). C NMR (75 MHz, C
D
6 6
, 25 °C): δ 27.99,
7.95, 27.90, 27.86, 27.81, 27.49, 27.46, 27.43 (CH of Cy),
3.88, 23.28, 23.05, 22.84, 22.72 (1:2:2:1:1 for ipso-CH of Cy),
2
2
0
2
2
2
9
.57 (Si(CH
5 °C): δ -2.34, -56.35, -65.10, -65.27, -67.04 (1:2:1:2:2).
Synthesis of Cp Ti[(c-C Si 11][OSiMe (CH SiMe
OEt)] (2g). An excess of freshly distilled HSiMe (OEt) (1.0
mmol) was added dropwise to a toluene solution (5.0 cm ) of
c (0.5 mmol) and Pt(dvs) catalyst (1 mol %, dvs ) divinyltet-
3 2 6 6 3
) H). Si NMR (76 MHz, C D , 0.02 M Cr(acac) ,
2
5
H
9
)
7
7
O
2
2
)
2
2
-
(
2
3
2
2
ramethyldisiloxane), and the mixture was stirred at room
temperature for 24 h. After short column chromatography on
alumina and solvent evaporation, a viscous yellow solid of 2g
2
4
were solved by direct methods using SIR97 and expanded
2
5
using Fourier techniques, DIRDIF94. The non-hydrogen
atoms were refined anisotropically by full-matrix least-squares
calculations, and hydrogen atoms were placed at their geo-
metrically calculated positions and refined isotropically. Se-
lected crystallographic parameters and bond distances and
angles are given in Tables 2-4. The detailed final atomic
parameters are given in the Supporting Information.
1
3
was obtained almost quantitatively. The C NMR spectra
DEPT) shows that the product is 2g, bearing a linear -SiCH
CH Si- group, together with a trace amount of the byproduct
g′, with branched -SiCH(CH )Si- bonding. Because of the
high reactivity of the ethoxysilyl group, complete purification
(
2
-
2
2
3
1
has not been achieved. 2g: H NMR (300 MHz, C
6
D
6
, 25 °C) δ
), 3.58 (q, J ) 7.2 Hz, 2H,
), 2.10-1.55 (br m, 56H, CH of Cy), 1.24-1.14 (br
CH ), 0.55 (s,
Si), 0.14 (s, 6H), 0.13 (s, 6H,
); C{ H} NMR (75 MHz, CDCl , 25 °C) δ 117.74,
), 58.10 (OCH CH ), 28.82-27.47 (m, CH ), 25.57,
4.71, 24.23, 23.48, 23.45 (1:2:2:1:1 for CH), 19.06 (OCH CH ),
0.00, 8.29 (Si(CH Si), -0.10, -2.30 (Si(CH ); IR spectrum
3
6
.30 (s, 5H, C
5 5 5 5
H ), 6.03 (s, 5H, C H
OCH CH
2
3
2
Acknowledgment. This work was supported in part
by a Grant-in Aid for Scientific Research (No. 16560676)
from the Ministry of Education, Science, Sports, and
Culture.
3
m, 7H, CH of Cy), 1.16 (t, J ) 7.2 Hz, 3H, OCH
2
3
2 2
2H), 0.54 (s, 2H, both Si(CH )
13
1
both Si(CH
)
3 2
3
1
2
1
16.96 (C
H
5 5
2
3
2
2
3
Supporting Information Available: Tables giving full
details of the crystal structure determination. This material
is available free of charge via the Internet at http://pubs.acs.org.
)
2 2
3 2
)
(
KBr) 2949 (s), 2872 (s), 1450 (m), 1254 (m), 1110 (vs), 919 (s),
01 (s), 729 (m), 497 (m) cm-1
8
.
Synthesis of Cp
OEt)] (3g). A method similar to that for 2g was adopted by
CH
2 5 9 7 7 2 2 2 2
Zr[(c-C H ) Si O11][OSiMe (CH ) SiMe -
OM040082Q
(
using 3c in place of 2c. Again, 3g with a linear -SiCH
2
2
-
(
24) SIR97: Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, M.;
Si- connection was obtained together with a trace amount of
Giacovazzo, C.; Guagliardi, A.; Polidori, G.; Spagna, R. J. Appl.
Crystallogr. 1999, 32, 115.
1
the byproduct 3g′, with a branched connection. 3g: H NMR
(
25) DIRDIF94: Beurskens, P. T.; Admiraal, G.; Beurskens, G.;
(
300 MHz, C
3
6
D
6
, 25 °C) δ 6.37 (s, 5H, C
.62 (q, J ) 7.0 Hz, 2H, OCH CH ), 2.11-1.40 (br m, 56H,
of Cy), 1.28-1.05 (br m, 7H, CH of Cy), 1.20 (t, J ) 7.0
5 5 5 5
H ), 6.15 (s, 5H, C H ),
Bosman, W. P.; de Gelder, R.; Israel, R.; Smits, J. M. M. The DIRDIF-
4 Program System; Technical Report of the Crystallography Labora-
tory; University of Nijmegen, Nijmegen, The Netherlands, 1994.
3
2
3
9
3
CH
2