Octa, deca, and dodeca(4-nitrophenyl) cage silsesquioxanes via 4-trimethylsilylphenyl derivatives

Article abstract of DOI:10.1039/b923122f

Pure octa, deca, and dodeca(4-nitrophenyl) cage silsesquioxanes were obtained by regio-selective 4-nitration of octa, deca, and dodeca(4- trimethylsilylphenyl) cage silsesquioxanes via ipso-substitution of trimethylsilyl-phenyl bonds by fuming nitric acid. 3-Nitration of octa(4-methylphenyl)octasilesquioxane was also described. The starting octa(4-methyl-, 4-isopropyl- and 4-trimethylsilylphenyl)octasilsesquioxanes were selectively formed in 9-21% isolated yield in the presence of hydrochloric acid. Mixtures of octa, deca and dodecasilsesquioxanes, with decasilsesquioxane as the main component, were formed in the presence of tetrabutylammmonium fluoride as a catalyst. All the cage compounds could be separated mainly by crystallization. The Royal Society of Chemistry 2010.

Full text of DOI:10.1039/b923122f

View Article Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/dalton | Dalton Transactions
Octa, deca, and dodeca(4-nitrophenyl) cage silsesquioxanes via
4-trimethylsilylphenyl derivatives
Akio Miyazato, Chitsakon Pakjamsai and Yusuke Kawakami*
Received 4th November 2009, Accepted 6th January 2010
First published as an Advance Article on the web 5th February 2010
DOI: 10.1039/b923122f
Pure octa, deca, and dodeca(4-nitrophenyl) cage silsesquioxanes were obtained by regio-selective
4-nitration of octa, deca, and dodeca(4-trimethylsilylphenyl) cage silsesquioxanes via ipso-substitution
of trimethylsilyl-phenyl bonds by fuming nitric acid. 3-Nitration of octa(4-methylphenyl)-
octasilesquioxane was also described. The starting octa(4-methyl-, 4-isopropyl- and
4-trimethylsilylphenyl)octasilsesquioxanes were selectively formed in 9–21% isolated yield in the
presence of hydrochloric acid. Mixtures of octa, deca and dodecasilsesquioxanes, with
decasilsesquioxane as the main component, were formed in the presence of tetrabutylammmonium
fluoride as a catalyst. All the cage compounds could be separated mainly by crystallization.
nitro group over phenyl–silsesquioxane silicon linkage in cage 4-
TMSPh-oligosilsesquioxanes.
Introduction
An increasing need has been noted for the introduction of func-
tional groups to polyhedral oligomeric silsesquioxanes (POSS),
such as cage octa-, deca-, and dodecasilsesquioxane, [(RSiO1.5)n,
R-T8, R-T10 and R-T12] to be used as the building blocks
to construct a variety of nano-hybrid materials with precise
structure.1-12 Phenyl derivatives, to which functional groups can
be introduced by a variety of reactions, are the most convenient
for the purpose. However, it is normally very difficult to directly
synthesize functionalized phenyl-substituted cages, and thus func-
tionalization of phenyl groups attached to cage silicon atoms has
been long desired.
The amino group is one of the versatile functional groups used
to construct new structures by condensation or addition reactions,
and introduction of the nitro group is the key to introducing the
amino group to an aromatic group. Laine and Olson reported the
nitration of Ph-T8 (R = phenyl, Ph) by fuming nitric acid and
further reduction and application of the product.13 However, the
multi-, but incomplete functionalization of the phenyl ring often
made it difficult to correlate the properties of the system with
the structure. Recently, Zhang reported an improved synthesis
of octa-nitrated Ph-T8, but the position of the nitration was not
controlled. Nitration at the 2-, 3- and 4- positions had occurred.14
We also confirmed their result.
Here, we firstly report the synthesis and separation of octa[4-
methyl (4-M), 4-isopropyl (4-P)- and 4-TMS-Ph]-T8, and deca-,
and dodeca- analogues, namely [4-MPh-T10, 4-TMSPh-T10, and
4-TMSPh-T12]. Next, regio-selective 3-nitration of 4-MPh-T8, and
selective nitration of 4-TMSPh-T8, -T10, and -T12 at the 4-position
via ipso-substitution of TMS–phenyl bonds were described.
Results and discussion
4-Methylphenyl(4-MPh)-T8, 4-PPh-T8 and 4-TMSPh-T8 were
obtained in moderate yield by direct acidic hydroly-
sis of (4-MPh)triethoxysilane, (4-PPh)triethoxysilane, and (4-
TMSPh)triethoxysilane in the presence of hydrochloric acid (HCl).
Simple washing with ethanol gave pure 4-MPh-T8 and 4-PPh-
T8. Passage through a short silica gel column with hexane as
an eluent gave pure 4-TMSPh-T8. Hydrolysis of 4-substituted-
phenyltriethoxysilane in the presence of tetrabutylammmonium
fluoride (TBAF) gave a mixture of T8, T10 and T12 cages with
T10 as the major fraction. 4-Methylphenyl-T10 was obtained from
the mixture by crystallization using acetonitrile–THF (1 : 1). Treat-
ment of the mixture of 4-TMSPh cages firstly with hexane removed
4-TMSPh-T8 (11%) as a crystalline material. Following crystal-
lization using ethanol–hexane (1 : 4), crystalline 4-TMSPh-T12 was
obtained in 7% yield. Final crystallization using acetonitrile–THF
(1 : 3) gave crystalline 4-TMSPh-T10 in 30% yield. Each fraction
was purified by further recrystallization.
Meanwhile, it has been well recognized that the aromatic–
silicon bonds are susceptible to electrophilic cleavage. For example,
we reported the synthesis of an optically active bromosilane
by the cleavage of the naphthyl–silicon bond of optically active
silane by bromine.15 Eaborn reported that treatment of 1,4-
bis(trimethylsilyl)benzene by fuming nitric acid resulted in the
substitution of one trimethylsilyl (TMS) group by a nitro group.16
It would be interesting to establish the selective cleavage and
substitution of the phenyl–silicon linkage of phenyl–TMS by a
The typical reaction scheme is shown for 4-TMSPh POSS cages
in Scheme 1, and the results of the synthesis of 4-TMSPh-cages
are shown in Table 1.
Formation of T10 and T12 cages should be the result of the de-
composition of the T8 cage and re-assembly to thermodynamically
more stable cages, which are commonly observed under various
reaction conditions.8,9b,11b,11c,17 For example, Yokozawa reported
the formation of T8, T10 and T12 in the hydrolysis of cyclic hex-
asiloxanehexaol or dodecasiloxaneodecaol, phenylsilanetriol, or
trialkoxysilanes by amines.9b Bassindale reported the formation of
a mixture of cages from cyclic tetrasiloxanetetraol in the presence
School of Materials Science, Japan Advanced Institute of Science and Tech-
nology (JAIST), Asahidai 1-1, Nomi, Ishikawa, 923-1292, Japan. E-mail:
kawakami@jaist.ac.jp
This journal is
The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 3239–3244 | 3239
©

View Article Online
Table 1 Synthesis of 4-substituted Ph-POSS cages
Triethoxysilane
Catalyst
Solvent
T8 (Yield, %)
T10 (Yield, %)
T12 (Yield, %)
b
b
4-TMSPh
4-TMSPh
4-MePh
4-MePh
4-PPh
HCl
TBAF
HCl
TBAF
HCl
EtOH
CH2Cl2
EtOH
CH2Cl2
EtOH
21
11
21
10
9
30
7
b
b
a
b
41
b
a Not isolated. b Not detected by NMR.
Scheme 1 Synthesis of 4-TMSPh-T8, T10 and T12.
of TBAF.8 We noticed extensive rearrangement of the T8 cage
under azidation of octakis(3-chloropropyl)octasilsesquioxane to
produce a thermodynamically more stable mixture of octakis(3-
azidopropyl)-, deca(3-azidopropyl)-, and dodeca(3-azidopropyl)-
silsesquioxanes.18 Such cage rearrangement was also reported by
Rikowski.19
MS spectrum showed arrays of peaks differing in molar mass
by 15 (Fig. 2). The difference of 15 in the molar mass can
be explained by the disappearance of a methyl group, and the
removal of a methyl group can occur at the nitration stage
via ipso substitution, or at the ionization stage in MS analysis.
Considering the consistent and thoroughly assigned NMR of
octa(4-methyl-3-nitrophenyl)octasilsesquioxane shown in Fig. 1,
these arrays of peaks seemed to appear under ionization conditions
of the compound by eliminating a methyl group, and not by ipso
substitution.
Ipso substitution might be possible in the nitration of 4-PPh-
T8. However, the reaction gave the product with broadened
proton signals at around d = 8.1, 7.7 (2 : 1). Slow 3-nitration and
scrambling of the cage seemed to have occurred.
Although some decomposed products were formed when fum-
ing nitric acid was added to 4-TMSPh-T8 at room temperature,
almost completely pure nitrated products were obtained from 4-
TMSPh-T8, T10, and T12, if the addition of the acid was carried
out at -30 ◦C followed by reaction at room temperature for 10 h
as shown in Scheme 2.
Nitration of 4-TMS-POSS cages was examined. For com-
parison, nitration of (4-MPh)- and (4-PPh)-T8 were also car-
ried out. Nitration of 4-MPh-T8 by fuming nitric acid (added
at -30 ◦C), or by copper(II) nitrate trihydrate (copper(II) ni-
trate/octasilsesquioxane = 1.2/0.125 mol/mol) at room temper-
ature gave clean 3-nitration. When the starting material peak
in the 1H-NMR disappeared, three aromatic protons at d =
8.32, 7.88 and 7.45 and one CH3Ph at 2.64 ppm appeared,
which strongly indicated the formation of a 4-methyl-3-nitro-
phenyl group. There were no symmetrical doublet pairs of protons
assignable to 3- and 2-protons of 4-nitrophenyl derivatives, which
might be produced by ipso substitution. The accurate position of
nitration was confirmed by the help of NOE of the product in
NMR (Fig. 1). On irradiation of methyl protons, only one peak
at d = 7.88 ppm assigned to the 2-proton appeared as a positive
signal. Other correlation was also consistent with the 3-nitration.
Thus, the NOE analysis of the product confirmed the 3-nitration
of 4-MPh-T8.
1H, 13C, 29Si-NMR and IR data also support the formation of
the 4-nitrated product.
IR spectra of the 4-nitrophenyl-T8, T10, and T12 (4-NPh-T8, T10,
and T12) are shown in Fig. 3.
The spectra showed two strong peaks at 1345, 1515 (NPh-T8),
1349, 1520 (NPh-T10) and 1348, 1518 cm-1 (NPh-T12) assignable
29Si NMR showed only one peak at d = -79.2 ppm assignable
to the T3 structure.
=
MALDI-TOF MS showed an interesting phenomenon.
The highest mass of 1528 Da could be octa(4-methyl-3-
nitrophenyl)octasilsesquioxane with one 3-nitro group on each
phenyl group of the T8 cage [(CH3NO2PhSiO1.5)8-Na+], and the
to symmetric and antisymmetric stretching of the N O band.
29Si-NMR showed the disappearance of the singlet of the
trimethylsilyl groups of TMSPh-T8, T10 and T12 at d = -3.83,
-3.98 and -4.06, -4.13 ppm, and the appearance of about
3240 | Dalton Trans., 2010, 39, 3239–3244
This journal is
The Royal Society of Chemistry 2010
©

View Article Online
Conclusion
Nitration of 4-trimethylsilylphenyl Tn (n = 8, 10, 12) cages by
fuming nitric acid under controlled conditions gave clean 4-
nitration through ipso substitution in good yield.
Contrarily, nitration of 4-methylphenyl-T8 by copper(II) nitrate
trihydrate/acetic anhydride system and fuming nitric acid gave
clean 3-nitration.
Experimental
All reagents used were of analytical grade. 1H (500 MHz),13C
(125 MHz) and 29Si (99 MHz) NMR spectra were measured on
a Varian NMR spectrometer model Unity INOVA 500. Chemical
shifts were given in ppm (d). FT-IR spectra were measured with a
Perkin Elmer Spectrum One at room temperature. MALDI-TOF
MS spectra were recorded on a Voyager DE RP.
Octa(4-substituted-phenyl)octasilsesquioxanes
To ethanol (13 ml) solution of HCl (0.16 g, 4.6 mmol, HCl 35%) in
a 30 ml round-bottom flask, 4-substituted-phenyltriethoxysilane
(3.0 mmol), was added under vigorous stirring, and kept under
refluxing temperature of the solvent for 4 days. After cooling
to room temperature, the formed precipitate was filtered and
washed with ethanol. Pure enough compounds could be obtained
for 4-methyl and 4-isopropyl derivatives. Simple passage through
a silica gel column with hexane as an eluent gave pure 4-
trimethylsilylphenyl-T8. The obtained white powder was dried
under vacuum.
Octa(4-methylphenyl)octasilsesquioxane (4-MPh-T8). d: 1H
(CDCl3) 7.63 [d, 2H, JHH = 7.8 Hz, 2-H], 7.16 (d, 2H, JHH = 7.8 Hz,
3-H to methyl), 2.34 [s, 3H, 4-CH3]; 13C (CDCl3) 140.6, 134.3,
128.6, 127.0 [C6H4], 21.62 [CH3]; 29Si [CDCl3] -78.0. MALDI-
TOF MS m/z [M+Na]+: 1167. Calcd. for C56H56O12Si8: 1144.
(Yield 21%).
Fig. 1 NOE spectrum of octa(4-methyl-3-nitrophenyl)octasilsesquioxane.
a) 1H-NMR of octa(4-methyl-3-nitrophenyl)silsesquioxane. b) NOE
enhancement of 2-proton upon irradiation of 1-proton. c) NOE
enhancement of 1- and 3-protons upon irradiation of 2-proton. d) NOE
enhancement of 2-proton upon irradiation of 3-proton.
1
Octa(4-isopropylphenyl)octasilsesquioxane (4-PPh-T8). d: H
(Acetone-d6) 7.68 [d, 2H, JHH = 8.0 Hz, 2-H], 7.16 [d, 2H, JHH
=
8.0 Hz, 3-H to isopropyl], 2.89 [m, 1H, 4-CH(CH3)2], 1.24 [d, 6H,
4-CH(CH3)2]. 13C (CDCl3) 151.4, 134.4, 127.6, 126.0 [C6H4], 34.2
[CH(CH3)2], 24.0 [CH(CH3)2]. 29Si (CDCl3): -78.2. MALDI-TOF
MS m/z [M+Na]+: 1392. Calcd. for C72H88O12Si8: 1368. (Yield
9%).
1–2 ppm shifted cage peaks of NPh-T8, T10, and T12 at d = -79.2
(NPh-T8), -80.9 (NPh-T10) and d = -80.3, -82.2 ppm, respectively
(Fig. 4).
The T12 cage is composed of four 8-membered rings and four
10-membered rings, and two kinds of silicon atom are located
at the corners formed by two 10-memberd rings and one 8-
membered ring, or at the corners formed by two 8-membered rings
(indicated by purple in graphical abstract) and one 10-membered
ring (indicated by bold in graphical abstract). The ratio is 2 : 1.
Consistent with this consideration, contrary to the fact that only
one signal was observed for T8 and T10, two singlet signals were
observed for T12.
Octa(4-trimethylsilylphenyl)octasilsesquioxane (4-TMSPh-T8).
1
d: H (CDCl3) 7.72 [d, 2H, JHH = 8.0 Hz, 2-H], 7.52 [d, 2H,
JHH = 8.0 Hz, 3-H to trimethylsilyl], 0.254 [s, 9H, 4-(CH3)3Si]. 13
C
(CDCl3) 143.4, 133.3, 132.7, 130.5 [C6H4], -1.29 [(CH3)3Si]. 29Si
(CDCl3): -78.4, -3.83. MALDI-TOF MS m/z [M+Na]+: 1631.
Calcd. for C72H104O12Si16: 1608. (Yield 21%).
Formation of a mixture of cages by TBAF
This is the first report on the effective formation of 4-nitrophenyl
cage POSS derivatives. These pure nitro compounds, 4-nitroPh-T8
(NPh-T8), 4-nitroPh-T10 (NPh-T10), and 4-nitroPh-T12 (NPh-T12)
will find applications in designing new nano-hybrid materials with
precise structure.
To a dichloromethane (1 L) solution of TBAF (3 ml of a
1 mol L-1 solution in THF) and water (80 mmol) in a 2 L flask,
4-substituted-phenyltriethoxysilane (50 mmol), was added under
vigorous stirring at room temperature for 24 h. After the reaction
solution was washed with 5 ¥ 100 ml water, the organic layer
This journal is
The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 3239–3244 | 3241
©

View Article Online
Fig. 2 MALDI-TOF MS spectra of octa(4-methyl-3-nitrophenyl)silsesquioxane.
Scheme 2 Synthesis of 4-nitrophenyl (4-NPh)-T8, T10 and T12.
was separated and dried with Na2SO4, and concentrated to give a
colorless solid of the mixture of T8, T10 and T12 cages.
using ethanol–hexane (1 : 4) gave T12 cage as crystals (Yield 7%).
Final crystallization using acetonitrile–THF (1 : 3) gave T10 cage
as crystals (Yield 30%).
Deca(4-methylphenyl)decasilsesquioxane (4-MPh-T10). Treat-
ment of the product mixture firstly with acetonitrile–THF (1 : 1)
removed the T10 cage as a crystalline material (Yield 41%).
Following this, crystallization using acetone gave crystals of T8
Deca(4-trimethylsilylphenyl)decasilsesquioxane
(4-TMSPh-
1
T10). d: H (CDCl3): 7.55 [d, 2H, JHH = 8.0 Hz, 2-H], 7.39 [d,
2H, JHH = 8.0 Hz, 3-H], 0.23 [s, 9H, 4-(CH3)3Si]. 13C (CDCl3):
143.1, 133.3, 132.4, 131.0 [C6H4], -1.29 [(CH3)3Si]. 29Si (CDCl3):
-79.6, -3.98. MALDI-TOF MS m/z [M+Na]+: 2033. Calcd. for
C90H130O15Si20: 2010. (Yield 30%).
1
cage (Yield 10%). d: H (CDCl3): 7.48 [d, 2H, JHH = 7.8 Hz,
2-H], 7.05 [d, 2H, JHH = 7.8 Hz, 3-H to trimethylsilyl], 2.30
[s, 3H, 4-CH3]. 13C (CDCl3): 140.2, 134.2, 128.4. 127.5 [C6H4],
21.6 [CH3]. 29Si (CDCl3): -79.5. MALDI-TOF MS m/z [M+Na]+:
1453. Calcd. for C70H70O15Si10: 1430. (Yield 41%).
Dodeca(4-trimethylsilylphenyl)dodecasilsesquioxane (4-TMSPh-
1
Hydrolysis of 4-trimethylsilylphenyltriethoxysilane in the pres-
ence of TBAF gave a mixture of 4-TMSPh-T8, 4-TMSPh-T10 and
4-TMSPh-T12 with 4-TMSPh-T10 as the major fraction.
Treatment of the mixture firstly with hexane removed the T8 cage
as a crystalline material (Yield 11%). Following this, crystallization
T12). d: H (CDCl3): 7.54 [d, 2H, JHH = 8.0 Hz, 2-H], 7.45 [d,
4H, JHH=8.0 Hz, 2-H], 7.39 (d, 2H, JHH = 8.0 Hz, 3-H), 7.31 (d,
4H, JHH = 8.0 Hz, 3-H), 0.22 [s, 13H, 4-(CH3)3Si]. 13C (CDCl3):
142.9, 142.7, 133.4, 132.4, 132.3, 131.5, 131.2 [C6H4], -1.28, -1.31
[(CH3)3Si]. 29Si (CDCl3): -81.5, -79.4, -4.13, -4.06. MALDI-TOF
3242 | Dalton Trans., 2010, 39, 3239–3244
This journal is
The Royal Society of Chemistry 2010
©

View Article Online
Nitration of cages by fuming nitric acid
A 4-TMSphenyl POSS cage (0.06 mmol) was added to 1 ml of
fuming nitric acid with stirring at -30 ◦C. After addition was
complete, the solution was stirred for an additional 30 min, and
then stirred at room temperature for 10 h. The solution was poured
into 50 ml ice-water. The precipitates were filtered, washed with
water and ethanol. The obtained yellow powder was dried under
vacuum at room temperature.
Octa(4-nitrophenyl)octasilsesquioxane (4-NPh-T8). d: 1H
(THF-d8): 8.31 [2H, d, JHH = 8.7 Hz, 3-H], 8.06 [2H, d, JHH
=
8.7 Hz, 2-H]; 13C (Acetone-d6): 151.4, 136.7, 136.2, 123.7
[C6H4].29Si (Acetone-d6): -79.22; FT-IR: 1089 cm-1 [Si–O–Si],
1515 cm-1, 1345 cm-1 [N O2]. (Yield 94%).
=
Deca(4-nitrophenyl)decasilsesquioxane (4-NPh-T10). d: 1H
(THF-d8): 8.23 [2H, d, JHH = 8.7 Hz, 3-H], 8.12 [2H, d, JHH
=
8.7 Hz, 2-H]; 13C (Acetone-d6): 150.7, 137.8, 136.3, 123.4 [C6H4].
29Si (Acetone-d6): -80.92. FT-IR: 1095 cm-1 [Si–O–Si], 1520 cm-1,
1349 cm-1 [N O2]. (Yield 80%).
=
Dodeca(4-nitrophenyl)dodecasilsesquioxane (4-NPh-T12). d:
1H (THF-d8): 8.21 [1H, d, JHH = 8.7 Hz, 3-H], 8.13 [2H, d, JHH
8.7 Hz, 3-H], 7.92 [1H, d, JHH = 8.7 Hz, 2-H], 7.79 [2H, d, JHH
=
=
8.7 Hz, 2-H], 29Si (Acetone-d6): -80.34, -82.24. FT-IR: 1102 cm-1
Fig. 3 FT-IR spectra of 4-NPh-T8, T10, and T12.
[Si–O–Si], 1518 cm-1, 1348 cm-1 [N O2]. (Yield 33%).
=
Octa(4-methylphenyl)octasilsesquioxane (0.13 g, 0.1 mmol) was
similarly treated with fuming nitric acid. After reaction, the
solution was poured into 40 ml ice water. The precipitates were
filtered, washed with water and ethanol. The obtained yellow
powder was dried under vacuum. (0.12 g, 70%). d: 1H (Acetone-
d6): 8.32 [1H, s, 2-H to nitro], 7.88 [1H, d, JHH = 7.8 Hz, 2-H],
7.45 [1H, d, JHH = 7.8 Hz, 3-H)], 2.64 (3H, s, CH3). 29Si (CDCl3):
-79.17. FT-IR: 1087 cm-1 [Si–O–Si], 1518 cm-1, 1348 cm-1 [unti
symmmetric and symmetric stretching of nitro].
Nitration of cages by copper(II) nitrate trihydrate
Copper(II) nitrate trihydrate (15.0 mg, 1.2 mmol) was dissolved in
acetic anhydride (0.8 mL) followed by stirring in an ice bath for
10 min, and the system was left to warm to room temperature for
one hour. A solution of octa(4-methylphenyl)octasilsesquioxane
(0.14 g, 0.12 mmol) in chloroform (2 mL) was added to the
Cu(NO3)2/acetic anhydride solution under nitrogen atmosphere.
Stirring was continued for 10 h. The progress of the reaction was
monitored by NMR. Chloroform (10 mL) and water (10 mL)
were added to the reaction system, and stirred for a while until
the chloroform phase changed to colorless and the water phase
became blue. The separated chloroform phase was washed with
excess aqueous 5 wt% sodium carbonate solution, and stirred
vigorously for 1.3 h. The organic solution was dried on magnesium
sulfate overnight, and then filtered. Evaporation of the solvent
gave a yellow product. (0.178 g, 99%).
Fig. 4 29Si-NMR of 4-NPh-T8, T10 and T12.
Acknowledgements
C. Pakjamsai thanks the National Metal and Materials Technol-
ogy Center [MTEC], National Science and Technology Devel-
opment Agency [NSTDA], Ministry of Science, Technology and
Environment, Thailand for financial support during the research.
MS m/z [M+Na]+: 2435. Calcd. for C108H156O18Si24: 2412.
(Yield 7%).
This journal is
The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 3239–3244 | 3243
©

View Article Online
2945–2949; (b) A. R. Bassindale, H. Chen, Z. Liu, I. A. MacKinnon,
D. J. Parker, P. G. Taylor, Y. Yang, M. E. Light, P. N. Horton and M. B.
Hursthouse, J. Organomet. Chem., 2004, 689, 3287–3300.
9 (a) M. Unno, K. Takada and H. Matsumoto, Chem. Lett., 1998, 489–
490; (b) Y. Kawakami, K. Yamaguchi, T. Yokozawa, T. Serizawa, M.
Hasegawa and Y. Kabe, Chem. Lett., 2007, 36, 792–793.
10 (a) D. W. Lee and Y. Kawakami, Polym. J., 2007, 39, 230–238; (b) Y.
Kawakami, React. Funct. Polym., 2007, 67, 1137–1147; (c) C. Pakjamsai
and Y. Kawakami, Polym. J., 2004, 36, 455–464; (d) C. Pakjamsai, N.
Kobayashi, M. Koyano, S. Sasaki and Y. Kawakami, J. Polym. Sci.,
Part A: Polym. Chem., 2004, 42, 4587–4597; (e) C. Pakjamsai and Y.
Kawakami, Des. Monomers Polym., 2005, 8, 423–435.
11 (a) I. Imae and Y. kawakami, J. Mater. Chem., 2005, 15(43), 4581–4583;
(b) M. Y. Lo, C. Zhen, M. Lauters, G. E. Jabbour and A. Sellinger,
J. Am. Chem. Soc., 2007, 129, 5808–5809; (c) R. M. Laine, M. Roll,
M. Asuncion, S. Sulaiman, V. Popova, D. Bartz, D. J. Krug and P. H.
Mutin, J. Sol-Gel Sci. Technol., 2008, 46, 335–347.
12 (a) C. Zhang, F. Babonneau, C. Bonhomme, R. M. Laine, C. L. Soles,
H. A. Hristov and A. F. Yee, J. Am. Chem. Soc., 1998, 120, 8380–8391;
(b) T. S. Haddad, B. D. Viers and S. H. Phillips, J. Inorg. Organomet.
Polym., 2001, 11, 155–164; (c) G. Pan, J. E. Mark and D. W. Schaefer,
J. Polym. Sci., Part B: Polym. Phys., 2003, 41, 3314–3323.
13 (a) K. Olsson and C. Gro¨nwall, Arkiv Kemi., 1961, 17, 529–540; (b) R.
Tamaki, Y. Tanaka, M. Z. Asuncion, J. Choi and R. M. Laine, J. Am.
Chem. Soc., 2001, 123, 12416–12417.
Notes and references
1 R. H. Baney, M. Itoh, A. Sakakibara and T. Suzuki, Chem. Rev., 1995,
95, 1409–1430.
2 G. Li, L. Wang, H. Ni and C. U. Pittman Jr, J. Inorg. Organomet.
Polym., 2001, 11, 123–154.
3 V. Chandrasekhar, R. Boomishankar and S. Nagendran, Chem. Rev.,
2004, 104, 5847–5910.
4 K. Pielichowski, J. Njuguna, B. Janowski and J. Piechowski, Adv. Polym.
Sci., 2006, 201, 225–296.
5 (a) J. F. Brown Jr, L. H. Vogt Jr, A. Katchman, J. W. Eustance, K. M.
Kiser and K. W. Krantz, J. Am. Chem. Soc., 1960, 82, 6194–6195;
(b) J. F. Brown, L. H. Vogt and P. I. Prescott, J. Am. Chem. Soc.,
1964, 86, 1120–1125; (c) J. F. Brown, Jr., J. Am. Chem. Soc., 1965, 87,
4317–4324.
6 (a) F. J. Feher, J. Am. Chem. Soc., 1986, 108, 3850–3852; (b) F. J.
Feher, D. A. Newman and J. F. Walzer, J. Am. Chem. Soc., 1989, 111,
1741–1748; (c) F. J. Feher, T. A. Budzichowki and K. J. Weller, J. Am.
Chem. Soc., 1989, 111, 7288–7289; (d) F. J. Feher and D. A. Newman,
J. Am. Chem. Soc., 1990, 112, 1931–1936; (e) F. J. Feher, J. J. Schwab, D.
Soulivong and J. W. Ziller, Main Group Chem., 1997, 2, 123–132; (f) F. J.
Feher, T. A. Budzichowski, R. L. Blanski, K. J. Weller and J. W. Ziller,
Organometallics, 1991, 10, 2526–2528; (g) F. J. Feher, D. Soulivong
and G. T. Lewis, J. Am. Chem. Soc., 1997, 119, 11323–11324; (h) F. J.
Feher, R. Terroba and J. W. Ziller, Chem. Commun., 1999, 2153–2154;
(i) F. J. Feher, R. Terroba and J. W. Ziller, Chem. Commun., 1999, 2309–
2310.
14 J. Zhang, R.-W. Xu and D.-S. Yu, J. Appl. Polym. Sci., 2007, 103,
1004–1010.
7 (a) E. G. Shockey, A. G. Bolf, P. F. Jones, J. J. Schwab, K. P. Chaffee,
T. Haddad and J. D. Lichtenhan, Appl. Organomet. Chem., 1999,
13, 311–327; (b) US Pat., 5,484,867, 1996; (c) International Patent
PCT/US00/21455, 2000; (d) US Pat., 6,927,270 B2, 2005; (e) US Pat.,
2004/0068075 A1, 2004; (f) US Pat 0263318 A1, 2006.
8 (a) A. R. Bassindale, Z. Liu, I. A. Mackinnon, P. G. Taylor, Y. Yang,
M. E. Light, P. N. Horton and M. B. Hursthouse, Dalton Trans., 2003,
15 K. Suzuki, Y. Kawakami, D. Velmurugan and T. Yamane, J. Org. Chem.,
2004, 69, 5383–5389.
16 F. B. Deans and C. Eaborn, J. Chem. Soc., 1957, 498–499.
17 Z. Li and Y. Kawakami, Chem. Lett., 2008, 37(7), 804–805.
18 V. Ervithayasuporn, X. Wang and Y. Kawakami, Chem. Commun.,
2009, 5130–5132.
19 E. Rikowski and H. C. Marsmann, Polyhedron, 1997, 16, 3357–3361.
3244 | Dalton Trans., 2010, 39, 3239–3244
This journal is
The Royal Society of Chemistry 2010
©