Tip-substituted cage and cyclic silanols

Article abstract of DOI:10.1016/S0022-328X(03)00541-2

Synthesis of novel cage and cyclic silanols bearing Tip (2,4,6-triisopropylphenyl) groups was performed. Tip-substituted silanetriol, TipSi(OH)₃ (1) was prepared from TipSiCl ₃, and can be handled without special care in the air. The versatility of this silanol is amply demonstrated as a starting material of various silanols with novel frameworks. Thus, the condensation of 1 using 2-chloro-1,3-dimethylimidazolinium chloride as a dehydrating agent afforded (TipSi)₅O₇OH (2) in 45% yield. When 1 was treated with (TipSiCl₂)₂O, cis, trans-cyclotrisiloxanetriol (3) as well as a novel incompletely condensed silsesquioxane, (TipSi)₄O₅(OH)₂ (4) were obtained. In addition, the dehydrochlorinative condensation of (TipSiCl₂)₂O and (TipSi(OH)₂) ₂O afforded 4 as single product. The structures of all these novel silanols were determined by X-ray crystallography, and their unique structures (hydrogen-bonded aggregates or intramolecular hydrogen bonding) were demonstrated.

Full text of DOI:10.1016/S0022-328X(03)00541-2

Journal of Organometallic Chemistry 686 (2003) 175Á182
/
www.elsevier.com/locate/jorganchem
Tip-substituted cage and cyclic silanols
Masafumi Unno, Toshihiko Tanaka, Hideyuki Matsumoto *
Department of Nano-material Systems, Graduate School of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan
Received 1 April 2003; received in revised form 28 May 2003; accepted 6 June 2003
Abstract
Synthesis of novel cage and cyclic silanols bearing Tip (2,4,6-triisopropylphenyl) groups was performed. Tip-substituted
silanetriol, TipSi(OH)3 (1) was prepared from TipSiCl3, and can be handled without special care in the air. The versatility of this
silanol is amply demonstrated as a starting material of various silanols with novel frameworks. Thus, the condensation of 1 using 2-
chloro-1,3-dimethylimidazolinium chloride as a dehydrating agent afforded (TipSi)5O7OH (2) in 45% yield. When 1 was treated with
(TipSiCl2)2O, cis,trans-cyclotrisiloxanetriol (3) as well as a novel incompletely condensed silsesquioxane, (TipSi)4O5(OH)2 (4) were
obtained. In addition, the dehydrochlorinative condensation of (TipSiCl2)2O and (TipSi(OH)2)2O afforded 4 as single product. The
structures of all these novel silanols were determined by X-ray crystallography, and their unique structures (hydrogen-bonded
aggregates or intramolecular hydrogen bonding) were demonstrated.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Silsesquioxane; Silanol; Crystal structure; Hydrogen bonding; Nano-size aggregate
1. Introduction
structure determination of (TipSi)5O6OH (2), cis,trans-
(TipSi(OH)O)3 (3), and (TipSi)4O5(OH)2 (4); (3) struc-
ture of the hydrogen-bonded aggregate of 3.
Cyclic and cage silanols, often quoted as incompletely
condensed silsesquioxanes, have been extensively stu-
died, especially on their capability as starting materials
of metallosiloxanes [1]. In addition, recent development
of the chemistry of cage silsesquioxanes has forced more
focus on their synthesis from silanols [2]. Nevertheless,
the reactions from silanols are still limited, and only
known for readily available silanols [3]. Recently, we
have isolated the cyclotetrasiloxanetetraol, (i-
PrSi(OH)O)4, and shown its versatility as precursors of
tricyclic laddersiloxane [4], hexasilsesquioxane [4], octa-
silsesquioxane [5], hydrogen-bonded supramolecular
aggregates [6], and pentacyclic laddersiloxanes [7]. These
preceding results prompted us to construct cyclic or cage
silanols of new types, which may lead to novel silses-
quioxane chemistry. In this article, we report the
following new results: (1) preparation of Tip-substituted
silanetriol (1) and disiloxanetetraol (6); (2) synthesis and
2. Results and discussion
2.1. Synthesis of (TipSi)5O7OH (2)
The starting TipSi(OH)3 (1) was readily prepared by
the hydrolysis of the corresponding TipSiCl3 in 70%
yield (Scheme 1). This silanetriol 1 was identified by
spectroscopic analyses. Despite the bulkiness of Tip
1
group, NMR spectra showed no hindered rotation; H-
and 13C-NMR spectra showed sharp peaks of substi-
tuents. The 29Si chemical shift (d ꢀ
/
52.30) was in good
accordance with that of 2-naphthylsilanetriol (d ꢀ54.3)
[8].
/
In the present work, the condensation of 1 was carried
out using 2-chloro-1,3-dimethylimidazolinium chloride
(DMC). Previously, we showed that dicyclohexylcarbo-
diimide (DCC) was effective for the condensation of
* Corresponding author. Address: Department of Applied
Chemistry, Gunma University, 1-5-1 Tenjin-cho, Kiryu 376-8515,
RSi(OH)3 (Rꢁi-Pr [5], t-Bu, and 1,1,2-trimethylpropyl
/
[9]) leading to the hexasilsesquioxane, T6. In fact, in the
case of 1, treatment with DCC afforded (TipSi)6O9 in
Japan. Tel.: ꢂ
/
81-277-30-1293; fax: ꢂ
/
81-277-30-1291.
E-mail address: matumoto@chem.gunma-u.ac.jp (H. Matsumoto).
0022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00541-2

176
M. Unno et al. / Journal of Organometallic Chemistry 686 (2003) 175Á182
/
and ꢀ
trans-isomer, and was in good agreement with that of
all-cis-(PhSi(OH))3 (d ꢀ64.1) [11]. Compound 3 was
/60.84) clearly indicated the generation of cis,-
/
probably generated by the dehydration of 1 and 5 to
form dichlorohydroxycyclotrisiloxane, followed by hy-
drolysis at the workup process. Both cis,cis- and
cis,trans-isomers are possibly obtained in this reaction,
however, steric hindrance of cis-Tip groups over-
whelmed the stabilization by more hydrogen bonding
expected in cis,cis-3, resulting in the generation of only
cis,trans-isomer. Similarly, single isomer of 4 was
obtained probably by the steric reason.
Scheme 1.
20% yield, but no silanols were given [10]. In pursuit of
more effective dehydration agent, we came upon DMC;
this reagent can be used at lower temperature than
DCC, thus more favorable for silanol synthesis. As
shown in Scheme 1, reaction of silanetriol 1 with DMC
and diethylamine in CH2Cl2 led to the formation of
cage-type silanol (TipSi)5O7OH (2) in 45% yield. The
reaction was monitored by HPLC, and the intermediacy
of disiloxanetetraol 6 and following T4(OH)2 4 was
confirmed. Obviously, instead of the intramolecular
dehydration of 4, reaction of 4 with 1 predominated to
form 2 exclusively.
2.3. Synthesis of (TipSi)4O5(OH)2 (4) and attempted
synthesis of T4
In order to prepare 4 in a better yield, and also with
hoping to synthesize still-unknown tetrasilsesquioxane
T4, we then tried the reaction of tetrachlorosiloxane 5
and disiloxanetetraol 6 (Scheme 3). Preparation of
disiloxanetetraol 6 was effected by the hydrolysis of
tetrachlorosiloxane 5 with four equivalents of aniline in
water and ether. The spectroscopic analysis elucidated
its structure (29Si-NMR peak at d ꢀ
di(2-naphthyl)disiloxanetetraol [8]).
/
63.07 vs. ꢀ62.4 for
/
The reaction of tetrachloride 5 and tetraol 6 in
pyridine proceeded at 68 8C, and both starting materials
disappeared in 3 days. After usual workup, separation
with dry column chromatography followed by recrys-
tallization gave 4 in 9% yield. Unfortunately, with
multiple trials and investigating reaction conditions, T4
was not obtained. Compound 4 is stable in the air, and
resisted further dehydration with known reagents. Even
exposure of 4 to basic or acidic media did not lead to the
formation of tetrasilsesquioxane.
2.2. Synthesis of cyclotrisiloxanetriol, (TipSi(OH)O)3
(3) and (TipSi)4O5(OH)2 (4)
Dehydration of silanols is the most direct synthesis of
silsesquioxanes, however, controlling reaction condition
is crucial for the synthesis of incompletely condensed
silsesquioxanes. Recently, we have demonstrated the
dehydrochloric condensation of silanol and chlorosilane
proceeded smoothly to give silsesquioxanes [7]. We then
applied this reaction to 1 and chlorosiloxanes (Scheme
2.4. Structure of (TipSi)5O7OH (2) and
(TipSi)4O5(OH)2 (4)
2). When TipSiCl3 was treated with pyridineÁ
THF at 0 8C, partial hydrolysis occurred and 1,3-
bis(2,4,6-triisopropylphenyl)tetrachlorodisiloxane (5)
/water in
The structures of 2 and 4 were established by X-ray
crystallography [12]. Single crystals of 2 suitable for X-
was obtained in 39% yield. The reaction of this
tetrachlorodisiloxane 5 with silanetriol 1 in pyridine
resulted in the formation of cis,trans-cyclotrisiloxane-
triol, (TipSi(OH)O)3 (3, 13%) and (TipSi)4O5(OH)2 (4,
5%). The result of 29Si-NMR of 3 (2:1 ratio at d ꢀ
60.00
/
Scheme 2.
Scheme 3.

M. Unno et al. / Journal of Organometallic Chemistry 686 (2003) 175Á
/182
177
Fig. 1. Molecular drawings of 2 and 4.
ray analysis were obtained by recrystallization from
THFÁMeOH. The molecular structure is shown in Fig.
1. Crystallographic data are summarized in Table 1, and
106.48, respectively. This T5OH skeleton has not been
reported to date, however, these values are similar to
those in hexasilsesquioxanes, i.e., TipT6 [10] or i-PrT6
[4], consisted of six- and eight-membered siloxane rings.
In most cases of silanols, molecules compose intra or
intermolecular hydrogen bonding in the crystals. In-
cidentally, 2 has bulky Tip groups geminal to the
hydroxyl groups, thus intramolecular hydrogen bonding
was impossible. Instead, one molecule of methanol was
inserted between two molecules of 2, and single crystal
was composed. The packing scheme is shown in Fig. 2.
/
selected bond lengths and angles are listed in Table 2.
˚
Average SiÃ
/
O bond length was 1.639 A, and average
SiÃ
/
OÃ
/
Si and OÃ
/
SiÃO bond angles were 131.78 and
/
Table 1
Summary of crystal data, data collection, and refinement of 2Á
/
4
2
3
4
Formula
Molecular weight 1318.21
C76H120Si5O9
C51H88Si3O9
929.51
Colorless prism Colorless prism Colorless prism
C60H94Si4O7
1039.74
Table 2
Crystal descrip-
tion
˚
Selected bond lengths (A) and angles (8) for 2
Crystal size (mm) 0.40ꢃ
0.40
Triclinic
/
0.40ꢃ
/
0.40ꢃ
0.30
Triclinic
/
0.40ꢃ
/
0.40ꢃ
0.20
Triclinic
/
0.40ꢃ
/
Bond lengths
Si(1)Ã
Si(1)Ã
Si(2)Ã
Si(2)Ã
Si(3)Ã
Si(3)Ã
Si(4)Ã
Si(4)Ã
Si(5)Ã
Si(5)Ã
/
O(1)
O(6)
O(1)
O(8)
O(2)
O(7)
O(3)
O(6)
O(4)
O(7)
1.625(2)
1.640(2)
1.635(2)
1.620(3)
1.619(2)
1.647(2)
1.643(2)
1.642(2)
1.659(2)
1.640(2)
Si(1)Ã
Si(1)Ã
Si(2)Ã
Si(2)Ã
Si(3)Ã
Si(3)Ã
Si(4)Ã
Si(4)Ã
Si(5)Ã
Si(5)Ã
/
O(5)
1.639(3)
1.861(4)
1.631(3)
1.881(4)
1.637(2)
1.866(4)
1.650(3)
1.852(3)
1.641(3)
1.862(4)
Crystal system
Space group
/
/C(1)
¯
P/1
¯
P/1
¯
P/1
/
/
O(2)
C(16)
O(3)
C(31)
O(4)
C(46)
O(5)
C(61)
˚
a (A)
15.250(1)
18.800(1)
15.028(1)
98.721(4)
112.053(3)
81.242(4)
3925.6(5)
2
14.257(3)
17.414(4)
13.032(3)
106.78(1)
97.71(1)
103.90(1)
2933(1)
2
15.022(1)
18.097(1)
12.8776(8)
108.532(2)
93.203(6)
108.274(6)
3104.4(4)
2
/
/
˚
b (A)
/
/
˚
c (A)
/
/
a (8)
b (8)
g (8)
/
/
/
/
/
/
3
˚
V (A )
Z
/
/
Bond angles
O(1)ÃSi(1)Ã
O(5)ÃSi(1)Ã
O(1)ÃSi(2)Ã
O(2)ÃSi(3)Ã
O(3)ÃSi(3)Ã
O(3)ÃSi(4)Ã
O(4)ÃSi(5)Ã
O(5)ÃSi(5)Ã
Si(2)ÃO(2)Ã
Si(4)ÃO(4)Ã
Si(1)ÃO(6)Ã
Temperature (8C)
ꢀ
1.42
/
180.0
ꢀ
1.27
8047
/
12.0
ꢀ20.0
1.43
7732
/
m (cmꢀ1
)
/
/
O(5)
O(6)
O(8)
O(3)
O(7)
O(6)
O(5)
O(7)
Si(3)
Si(5)
Si(4)
109.3(1)
106.6(1)
105.7(1)
107.4(1)
105.0(1)
107.7(1)
103.8(1)
106.6(1)
150.3(2)
116.8(1)
131.9(2)
O(1)Ã
O(1)Ã
O(2)Ã
O(2)Ã
O(3)Ã
O(4)Ã
O(4)Ã
Si(1)Ã
Si(3)Ã
Si(1)Ã
Si(3)Ã
/
Si(1)Ã
Si(2)Ã
Si(2)Ã
Si(3)Ã
Si(4)Ã
Si(4)Ã
Si(5)Ã
O(1)Ã
O(3)Ã
O(5)Ã
O(7)Ã
/
O(6)
O(2)
O(8)
O(7)
O(4)
O(6)
O(7)
Si(2)
Si(4)
Si(5)
Si(5)
104.5(1)
107.3(1)
109.3(1)
108.4(1)
104.0(1)
104.3(1)
105.9(1)
141.6(2)
124.4(1)
125.3(1)
131.1(1)
/
/
/
/
Reflections mea- 12 915
sured
/
/
/
/
/
/
/
/
Reflections ob-
served
11 209
5113
5688
/
/
/
/
/
/
/
/
Parameters
810
576
649
/
/
/
/
R1 [I ꢀ
/
2.0s(I)]
0.071
wR2 (for all data) 0.161
0.085
0.094
0.474
0.62
0.076
0.164
0.008
0.54
/
/
/
/
/
/
/
/
(D/s)max
(D/r)max (e A
(D/r)min (e A
0.047
1.42
ꢀ3
˚
/
/
/
/
)
ꢀ3
˚
/
/
/
/
)
ꢀ
/
1.09
ꢀ
/
0.51
ꢀ/0.46

178
M. Unno et al. / Journal of Organometallic Chemistry 686 (2003) 175Á182
/
Fig. 2. Hydrogen bonding observed in 2 and 4.
The length of hydrogen bonding (O
/
Á Á Á
/
O distance) was
comprised only six-membered siloxane rings, SiÃ
/
OÃ
/
Si
˚
2.91 and 3.06 A.
Siloxanediol 4 (T4(OH)2) was recrystallized from
bond angles were smaller than those in 2, 3, or T6. Other
values are within the normal range. As shown in Fig. 2,
siloxanediol 4 possesses both intra and intermolecular
hydrogen bonding to form dimer in the crystal. The
THFÁMeOHÁH2O, and colorless single crystals were
/
/
obtained. Crystallographic data are summarized in
˚
distance of oxygen atoms were 2.98 A for intramolecular
˚
hydrogen bonding, and 3.06 A for intermolecular one.
This is the first example for bicyclo [3.3.1]siloxanes, and
the smallest cage silanol ever reported.
Table 1, and selected bond lengths and angles are listed
˚
O bond length was 1.639 A, and
in Table 3. Average SiÃ
/
average SiÃ
/
OÃ
/
Si and OÃ
/
SiÃO bond angles were 127.48
/
and 105.98, respectively. Because this molecule is
Table 3
˚
2.5. Structure of (TipSi(OH)HO)3 (3)
Selected bond lengths (A) and angles (8) for 4
Bond lengths
Several structural reports have appeared for cyclo-
trisiloxanetriols (T3(OH)3). In 1980, Russian group
reported the synthesis and structure determination of
(PhSi(ONa)O)3, which was obtained in two step from
PhSiCl3 [13]. Later, Roesky and his group reported the
first synthesis of free cyclic triol, cis,trans-[(2.6-
Me2C6H3)(N(SiMe3)Si(OH)O]3 starting from the re-
specting chlorosilane [14]. They also described the
synthesis of all-cis-[(Me3Si)2CHSi(OH)O]3 by the rea-
tion of tetraaminodisilane with H2O2/H2O [15]. Addi-
tionally, Fujita’s group reported the ship-in-a-bottle
Si(1)Ã
Si(1)Ã
Si(2)Ã
Si(2)Ã
Si(3)Ã
Si(3)Ã
Si(4)Ã
Si(4)Ã
/
O(1)
O(5)
O(1)
O(6)
O(2)
O(5)
O(3)
O(7)
1.633(3)
1.655(3)
1.634(3)
1.635(4)
1.639(3)
1.659(3)
1.631(3)
1.634(4)
Si(1)Ã
Si(1)Ã
Si(2)Ã
Si(2)Ã
Si(3)Ã
Si(3)Ã
Si(4)Ã
Si(4)Ã
/
O(4)
1.628(3)
1.853(5)
1.629(3)
1.857(5)
1.637(4)
1.851(5)
1.644(3)
1.865(5)
/
/C(1)
/
/
O(2)
C(16)
O(3)
C(31)
O(4)
C(46)
/
/
/
/
/
/
/
/
/
/
Bond angles
O(1)ÃSi(1)Ã
O(1)ÃSi(1)Ã
O(4)ÃSi(1)Ã
O(1)ÃSi(2)Ã
O(1)ÃSi(2)Ã
O(2)ÃSi(2)Ã
O(2)ÃSi(3)Ã
O(2)ÃSi(3)Ã
O(3)ÃSi(3)Ã
O(3)ÃSi(4)Ã
O(3)ÃSi(4)Ã
O(4)ÃSi(4)Ã
Si(1)ÃO(1)Ã
Si(3)ÃO(3)Ã
Si(1)ÃO(5)Ã
/
/
O(4)
C(1)
109.7(2)
108.4(2)
110.7(2)
106.2(2)
112.2(2)
112.5(2)
109.2(2)
108.1(2)
111.5(2)
106.5(2)
112.3(2)
111.8(2)
129.9(2)
129.2(2)
117.7(2)
O(1)Ã
O(4)Ã
O(5)Ã
O(1)Ã
O(2)Ã
O(6)Ã
O(2)Ã
O(3)Ã
O(5)Ã
O(3)Ã
O(4)Ã
O(7)Ã
Si(2)Ã
Si(1)Ã
/
Si(1)Ã
Si(1)Ã
Si(1)Ã
Si(2)Ã
Si(2)Ã
Si(2)Ã
Si(3)Ã
Si(3)Ã
Si(3)Ã
Si(4)Ã
Si(4)Ã
Si(4)Ã
O(2)Ã
O(4)Ã
/
O(5)
O(5)
C(1)
O(6)
O(6)
C(16)
O(5)
O(5)
C(31)
O(7)
O(7)
C(46)
Si(3)
Si(4)
103.4(2)
104.6(2)
119.6(2)
105.6(2)
106.1(2)
113.6(2)
103.8(2)
103.6(2)
120.1(2)
107.0(2)
105.2(2)
113.5(2)
130.7(2)
129.3(2)
/
/
/
/
/
/
C(1)
/
/
/
/
O(2)
C(16)
C(16)
O(3)
C(31)
C(31)
O(4)
C(46)
C(46)
Si(2)
Si(4)
Si(3)
/
/
formation of all-cis-(ArSi(OH)O)3 (ArꢁPh, 3,5-di-
/
/
/
/
/
methylpheyl, 2-naphthyl) taking advantage of the self-
assembled coordination cage [8,11]. However, only the
structures with all-cis form were determined by crystal-
lography, and the structure of cis,trans-cyclotrisiloxa-
netriol is still unknown to the best of our knowledge.
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
The obtained solid of 3 was recrystallized from THFÁ
/
/
/
/
/
MeOHby slow evaporation at room temperature to give
the crystals suitable for X-ray analysis [12]. The
molecular structure is shown in Fig. 3; crystallographic
data are summarized in Table 1, and selected bond
/
/
/
/
/
/
/
/
/
/

M. Unno et al. / Journal of Organometallic Chemistry 686 (2003) 175Á
/182
179
space-filling model (Fig. 5) clearly shows this structure:
hydrophilic groups compose a core surrounded by
hydrophobic Tip groups. The shape of this nano-wire
is rectangular with 1.4 nm by 1.7 nm. This kind of
hydrogen-bonded aggregate have been observed only in
siloxanepolyols, and observed for cyclotrisiloxanetriol
for the first time.
In summary, we have synthesized novel ring systems,
T5OH (2) and T4(OH)2 (4), and also the first cis,trans-
T3(OH)3 (3). The crystallographic analyses of these
compounds revealed their unique features, i.e., inter
and intramolecular hydrogen bonding, or nano-size
aggregates. Currently we are investigating the transfor-
mation of these silanols into novel siloxane cage
systems.
3. Experimental
Analytical HPLC was performed on a JASCO
875UV/880PU with a Chemco 4.6ꢃ
column. Preparative recycle-type HPLC was carried out
using JAI LC-908 with a Chemco 20ꢃ250 mm 7-ODS-
/
250 mm 5-ODS-H
Fig. 3. Molecular drawings of 3.
/
H column. Fourier transform nuclear magnetic reso-
nance spectra were obtained by a JEOL Model a-500
(1H at 500.00 MHz, 13C at 125.65 MHz, and 29Si at
99.25 MHz). Chemical shift were reported as d units
(ppm) relative to SiMe4, and residual solvents peaks
were used for standard. Electron impact mass spectro-
metry was performed with a JEOL JMS-DX302. Infra-
red spectra were measured with a SHIMADZU FTIR-
8700.
lengths and angles are listed in Table 4. Interestingly,
compound 3 adopted almost planar conformation un-
like cyclohexane. Average SiÃ
/
O bond length in the six-
membered ring was 1.645 A, and average angles were
˚
134.18 for SiÃOÃSi and 104.88 for OÃSiÃO. Those
/
/
/
/
values are similar to those in [(Me3Si)2CHSi(OH)O]3
[15]. Most interesting feature of 3 is revealed in its
packing diagram. In Fig. 4, possible hydrogen bonding
in the packing is shown. Two of the hydroxyl groups in
3 were connected via MeOH by hydrogen bonding,
resulted in the formation of infinite nano-size wire. The
3.1. Preparation of TipSi(OH)3 (1)
Ether (30 ml) solution of TipSiCl3 (2.06 g, 6.1 mmol)
was added to vigorously stirred emulsion of aniline (1.94
g, 21 mmol) and water (10.0 g, 0.56 mmol) in ether (30
ml) at 0 8C for 60 min. The mixture was stirred at 0 8C
for 3 h, then filtered through a glass filter. The filtrate
was concentrated, and colorless solid was obtained. The
solid was recrystallized from hexane to give analytically
Table 4
˚
Selected bond lengths (A) and angles (8) for 3
Bond lengths
Si(1)Ã
Si(1)Ã
Si(2)Ã
Si(2)Ã
Si(3)Ã
Si(3)Ã
/
O(1)
O(4)
O(1)
O(5)
O(2)
O(6)
1.631(4)
1.647(5)
1.651(5)
1.622(4)
1.633(4)
1.636(5)
Si(1)Ã
Si(1)Ã
Si(2)Ã
Si(2)Ã
Si(3)Ã
Si(3)Ã
/
O(3)
1.647(4)
1.899(5)
1.647(4)
1.888(6)
1.661(5)
1.876(5)
/
/C(1)
/
/
O(2)
C(16)
O(3)
C(31)
pure TipSi(OH)3 (1, 1.71 g, 70%). 1: Colorless solid,
1
/
/
/
/
m.p. 98Á
/
104 8C; H-NMR (DMSO-d6) 1.14 (d, 12H),
/
/
1.16 (d, 6H), 2.79 (sep, 1H), 3.90 (sept, 2H), 6.21 (s, 3H),
6.95 (s, 2H); 13C-NMR (DMSO-d6) 24.06, 25.40, 31.71,
33.79, 120.40, 130.20, 148.87, 155.71; 29Si-NMR
Bond angles
O(1)ÃSi(1)Ã
O(1)ÃSi(1)Ã
O(3)ÃSi(1)Ã
O(1)ÃSi(2)Ã
O(1)ÃSi(2)Ã
O(2)ÃSi(2)Ã
O(2)ÃSi(3)Ã
O(2)ÃSi(3)Ã
O(3)ÃSi(3)Ã
Si(1)ÃO(1)Ã
Si(1)ÃO(3)Ã
/
/
O(3)
C(1)
104.6(2)
111.9(2)
110.5(3)
105.2(2)
114.9(3)
109.5(2)
104.6(2)
114.9(3)
111.0(3)
133.3(3)
134.9(3)
O(1)Ã
O(3)Ã
O(4)Ã
O(1)Ã
O(2)Ã
O(5)Ã
O(2)Ã
O(3)Ã
O(6)Ã
Si(2)Ã
/
Si(1)Ã
Si(1)Ã
Si(1)Ã
Si(2)Ã
Si(2)Ã
Si(2)Ã
Si(3)Ã
Si(3)Ã
Si(3)Ã
O(2)Ã
/
O(4)
O(4)
C(1)
O(5)
O(5)
C(16)
O(6)
O(6)
C(31)
Si(3)
109.2(2)
107.6(2)
112.6(3)
107.5(2)
111.2(3)
108.6(2)
108.7(2)
108.5(2)
108.9(3)
134.1(3)
/
/
/
/
(DMSO-d6) d ꢀ52.30; MS (70 eV) m/z (%) 282
/
/
/
C(1)
/
/
([M]ꢂ, 70), 249 (100), 240 (45), 231 (40), 225 (60); IR
(KBr) 3296, 2960, 2869, 1604, 1554, 1461, 1361, 1193,
/
/
O(2)
C(16)
C(16)
O(3)
C(31)
C(31)
Si(2)
Si(3)
/
/
/
/
/
/
1137, 1047, 877, 846, 758, 632 cmꢀ1
.
/
/
/
/
/
/
/
/
/
/
/
/
3.2. Preparation of (TipSiCl2)2O (5)
/
/
/
/
/
/
/
/
Water (90 mg, 5.0 mmol) and pyridine (0.79 g, 10
mmol) in THF (0.5 ml) was added dropwise to a
/
/

180
M. Unno et al. / Journal of Organometallic Chemistry 686 (2003) 175Á
/182
Fig. 4. Hydrogen bonding observed in 3.
solution of TipSiCl3 (3.37 g, 10 mmol) in 13 ml of THF
and 2.5 ml of ether at 0 8C for 30 min. The mixture was
stirred at 0 8C for additional 3 h. After removal of
solvent, hexane was added to the semisolid, and the
generated salt was filtered under nitrogen atmosphere.
Bulb-to-bulb distillation of the concentrated filtrate
gave 1,3-bis(2,4,6-triisopropylphenyl)tetrachlorodisilox-
ane (1.21 g, 39%). 5: Colorless semisolid, b.p 240 8C/3
mmHg; 1H-NMR (CDCl3) 1.18 (d, 24H), 1.24 (d, 12H),
2.87 (sept, 2H), 3.69 (sept, 4H), 7.06 (s, 4H): 13C-NMR
(CDCl3) 23.60, 24.86, 32.87, 34.30, 122.23, 123.57,
dried, and concentrated to give 1,3-bis(2,4,6-triisopro-
pylphenyl)-1,1,3,3-tetrahydroxydisiloxane (2.86 g 88%).
1
6: Colorless solid, m.p. 144Á
/
147 8C; H-NMR (DMSO-
d6) 1.05 (d, 24H), 1.14 (d, 12H), 2.77 (sept, 2H), 3.80
(sept, 4H), 6.21 (s, 4H), 6.91 (s, 4H); 13C-NMR (DMSO-
d6) 24.15, 25.52, 31.89, 33.90, 120.53, 130.21, 149.08,
155.89; 29Si-NMR (DMSO-d6) ꢀ
/
63.07; MS (70 eV) m/z
(%) 341 ([Mꢂ]ꢀ
267 (45); IR (KBr) 3723, 3055, 2964, 2869, 1604, 1554,
/
Tip, 20%), 326 (5), 298 (5), 281 (60),
1541, 1461,1421,1382, 1361, 1047, 846, 812 cmꢀ1
.
152.98, 156.15; 29Si-NMR (CDCl3) ꢀ
30.96; MS (70
/
eV) m/z (%) 620 ([Mꢂ], 53), 577 (18), 535 (10), 415
(100); IR (NaCl) 3723, 3055, 2964, 2869, 1604, 1554,
3.4. Synthesis of (TipSi)5O7OH (2)
1541, 1461,1421,1382, 1361, 1047, 846, 812 cmꢀ1
.
In a two-necked flask were placed TipSi(OH)3 (1.41 g,
5.00 mmol), diethylamine (3.53 g, 48.3 mmol), dry
CH2Cl2 (10 ml), and DMC (2.15 g, 11.3 mmol). The
solution was heated 40 8C for 5 days. Water (20 mg) was
added dropwise to the mixture, and the aqueous phase
was extracted three times with ether (30 ml each). The
combined organic phase was dried over anhydrous
magnesium sulfate and evaporated. The resulting semi-
solid was separated by recycle-type preparative GPC
and further recrystallized from THF-MeOH to give 3-
3.3. Preparation of (TipSi(OH)2)2O (6)
Acetone (15 ml) solution of TipSiCl3 (4.03 g, 11.9
mmol) was added dropwise to water (150 ml) at 0 8C for
10 min. The mixture was stirred at 0 8C for 6 h, then
warmed to room temperature (r.t.). The solid was
filtered, and the filtration was washed with hexane,
Fig. 5. Space-filling drawing of 3.

M. Unno et al. / Journal of Organometallic Chemistry 686 (2003) 175Á
/182
181
hydroxy-1,3,5,7,10-pentakis(2,4,6-triisopropylphe-
nyl)tricyclo[3.3.3.17,10]pentasiloxane (0.58 g, 45%). 2:
3.6. Reaction of (TipSiCl2)2O (5) and
(TipSi(OH)2)2O (6)
Colorless crystals, m.p. 229Á
(CDCl3) 0.80 (d), 0.89 (d), 0.95 (d) 1.05 (d), 1.21 (m),
3.74 (m), 6.91 (m), 6.96
/
231 8C; 1H-NMR
In a two-necked flask were placed 5 (0.31 g, 0.50
mmol), 6 (0.30 g, 0.55 mmol), and pyridine (3.4 mg). The
solution was heated to 68 8C for 3 days. Water (30 ml)
was added to the mixture, which was then stirred for 30
min. The mixture was washed with water (30 ml), and
the aqueous phase was extracted three times with ether
(30 ml each). The combined organic phase was dried
with anhydrous magnesium sulfate and evaporated. The
resulting semisolid was separated by dry column chro-
2.83 (sept), 3.40Á
/
3.64 (m), 3.66Á
/
(m); 13C-NMR (CDCl3) 23.64, 23.72, 23.81, 24.23,
24.69, 24.92, 25.52, 32.21, 32.59, 32.67, 32.78, 34.35,
120.65, 120.77, 121.30, 121.46, 123.89, 151.10, 151.61,
156.45, 156.67, 156.87, 157.17; 29Si-NMR (CDCl3) ꢀ
59.34, ꢀ67.55, ꢀ68.21, MS (70 eV) m/z (%) 1285
([M]ꢂ, 80), 1081 ([M]ꢂꢀ
Tip, 81); IR (KBr) 3420, 2963,
2870, 1605, 1458, 1420, 1383, 1362, 1086, 1057, 1001,
961, 878, 735, 625 cmꢀ1
/
/
/
/
matography (hexane/etherꢁ8/2) and further recrystal-
/
.
lized from THF-MeOH to give (TipSi)4O5(OH)2 (4,
0.024 g, 9%).
3.5. Synthesis of cyclotrisiloxanetriol, Tip3Si3(OHO)3
(3) and (TipSi)4O5(OH)2 (4)
3.7. X-ray crystallography (general procedure)
Single crystals were coated and mounted on the glass
fiber using epoxy adhesive, and were cooled by a Rigaku
nitrogen-flow low-temperature apparatus. All measure-
ments were made on a Rigaku RAXIS-IVꢂꢂ imaging
plate diffractometer using graphite monochromated
THF (50 ml) solution of (TipSiCl2)2O (5, 0.657 g, 1.06
mmol) was added dropwise to a solution of TipSi(OH)3
(1, 0.600 g, 2.13 mmol) and pyridine (1.02 g, 12.9 mmol)
at r.t. for 120 min. The solution was stirred for 2 days,
and then heated to 110 8C for 6 days. The mixture was
washed with water (50 ml), and the aqueous phase was
extracted three times with ether (50 ml each). The
combined organic phase was dried over anhydrous
magnesium sulfate and evaporated. The resulting semi-
solid was separated by dry column chromatography
MoÁKa radiation. Indexing was performed from four
/
stills that were exposed for 60 s. The data were collected
to a maximum 2u value of 64.68. A sweep of data was
done using f oscillations from in 0.58 steps. The
exposure rate was 180.0 s per degree. The detector
swing angle was ꢀ0.158. The crystal-to-detector dis-
/
(hexane/etherꢁ8/2), and further recrystallized from
/
tance was 99.89 mm. Readout was performed in the
0.100 mm pixel mode. The structure was solved by direct
methods and expanded using Fourier techniques. The
non-hydrogen atoms were refined anisotropically, and
hydrogen atoms were refined isotropically. All calcula-
tions were performed using the CRYSTALSTRUCTURE
crystallographic software package.
THF and MeOH to give 1,3,5-trihydroxy-1,3,5-
tris(2,4,6-triisopropylphenyl)cyclotrisiloxane (3, 0.109
g, 13%) and cis-3,7-dihydroxy-1,3,5,7-tetrakis(2,4,6-trii-
sopropylphenyl)bicyclo[3.3.1]tetrasiloxane (4, 0.025 g,
1
5%). 3: Colorless needles, m.p. 174Á
/
177 8C; H-NMR
(CDCl3) 1.11 (d, 12H), 1.15 (d, 12H), 1.23 (d, 12H), 1.26
(d, 6H,), 1.29 (d, 12H), 2.81Á
/
2.91 (m, 3H), 3.68 (sept,
4H), 3.84 (sept, 2H), 7.03 (m, 4H), 7.09 (m, 2H); 13C-
NMR (CDCl3) 23.72, 23.77, 23.80, 25.06, 25.21, 25.28,
32.66, 32.74, 34.32, 121.19, 121.49, 124.23, 124.65,
151.14, 151.19, 156.32, 156.43; 29Si-NMR (CDCl3)
Acknowledgements
ꢀ
/
60.00, ꢀ
/
60.84; MS (EI, 70 eV) m/z (%) 792 ([Mꢂ],
Tip, 100); IR (KBr) 447, 2961, 2930,
2870, 1605, 1555, 1541, 1464, 1420, 1383, 362, 1084,
This work was support by a grant from the Ministry
of Education, Culture, Sports, Science and Technology
of Japan (Grant-in-Aid No. 12640510) an CREST-JST.
12), 588 ([Mꢂ]ꢀ
/
1024, 878, 735, 633 cmꢀ1. 4: Colorless crystals, m.p.
1
280Á
/
281 8C; H-NMR (acetone-d6) 0.96 (d, 24H), 1.15
(d, 36H), 1.23 (d, 12H), 2.90 (sept, 4H), 3.75 (sept, 4H),
3.82 (sept, 4H), 7.00 (s, 4H), 7.12 (s, 4H); 13C-NMR
(CDCl3) 17.89, 18.26, 23.71, 23.75, 24.11, 24.82, 24.96,
25.06, 25.15, 32.52, 32.65, 32.80, 34.24, 34.38, 58.50,
59.63, 121.02, 121.19, 121.30, 121.57, 122.04, 148.64,
151.78, 152.03, 156.40, 156.46, 156.59, 156.62, 156.96;
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/
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