Synthesis and crystal structure of disiloxane-1,3-diols and disiloxane-1,1,3,3-tetraol

Article abstract of DOI:10.1016/j.jorganchem.2007.01.016

1,3-Dimethyl- or 1,3-divinyl-1,3-di-t-butoxydisiloxane-1,3-diol and 1,3-diphenyldisiloxane-1,1,3,3-tetraol were synthesized by hydrolysis of the corresponding diisocyanatodisiloxanes and tetrachlorodisiloxane. The disiloxanediols were soluble in common or

Full text of DOI:10.1016/j.jorganchem.2007.01.016

Journal of Organometallic Chemistry 692 (2007) 2028–2035
www.elsevier.com/locate/jorganchem
Synthesis and crystal structure of disiloxane-1,3-diols
and disiloxane-1,1,3,3-tetraol
*
Ken-ichi Suyama, Takanori Nakatsuka, Takahiro Gunji , Yoshimoto Abe
Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
R&D Center, Teraoka Seisakusho Corporation, 1-4-22 Hiromachi, Shinagawa-ku, Tokyo 140-8711, Japan
Received 10 October 2006; received in revised form 11 January 2007; accepted 11 January 2007
Available online 20 January 2007
Abstract
1,3-Dimethyl- or 1,3-divinyl-1,3-di-t-butoxydisiloxane-1,3-diol and 1,3-diphenyldisiloxane-1,1,3,3-tetraol were synthesized by hydro-
lysis of the corresponding diisocyanatodisiloxanes and tetrachlorodisiloxane. The disiloxanediols were soluble in common organic sol-
vents and thermally very stable, therefore, they could be sublimed without decomposition. X-ray crystallography showed that the
disiloxane-1,3-diols in the crystal feature a 1.21 nm diameter columnar array with intermolecular hydrogen bonding. The disiloxane-
1,1,3,3-tetraol, on the other hand, revealed molecules with a gauche- and anti-conformation depending on crystallization method which
formed a columnar array and a sheet-like array, respectively. It was confirmed that these silanols can be potential building blocks for
ladder oligosilsesquioxanes.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Disiloxanepolyol; Crystal structure; Hydrogen bond assembly; Silsesquioxane
1. Introduction
between the all-cis-[i-PrSi(OH)O]4 and i-Pr2Si(OH)2 [12].
Because the ladder, sheet, cycle, and column type assem-
blies are generated by various types of hydrogen bondings,
the siloxanepolyols are also an interesting material for the
study of supramolecular organosilicon compounds [13].
From the viewpoint of silanols and, especially siloxane-
polyols, as a building block, the stability against the self-
condensation reaction is a serious problem to be overcome
because it decreases with an increase in the number of sil-
anol groups as well as the decrease in the steric hindrance
of the substituent [3,14]. According to this dependence, sil-
anols R4ꢀnSi(OH)n can be obtained by the hydrolysis of
R4ꢀnSiCln. However, disiloxanepolyols cannot be selec-
tively obtained, for the silanols are also formed as a by-
product provided that the substituents are not sterically
hindered [15]. This can be solved by using the sila-func-
tional disiloxanes as a stating material. However, very
few such materials are known so that it is practically
important to develop new synthetic routes of the sila-func-
tional disiloxane and oligosiloxanes, which allows us to
produce siloxanepolyols.
Silanol compounds serve as not only an interesting
model for surface hydroxyl groups of silica, but also are
building blocks of two- and three-dimensional metal-
lasiloxanes and silsesquioxanes [1,2]. Especially, siloxane-
polyols can be a material for the potential synthesis of
siloxanes and/or silsesquioxanes with ladder and cage
structures because they are constructed of the unit struc-
tures of the siloxanepolyols such as disiloxane and
cyclotetrasiloxane.
On the other hand, silanol compounds have been
reported to form hydrogen-bonded assemblies with them-
selves [3], alcohols [4], ethers [5], water [6], or amines [7].
For example, disiloxane-1,3-diols [R2Si(OH)]2O (R = Me
[8], Et [9], Pr [10], Ph [11]) have a columnar array with
an intermolecular hydrogen-bonded assembly. A 1.16 nm
diameter tube-like array was formed by the hydrogen bond
*
Corresponding author.
E-mail address: gunji@rs.noda.tus.ac.jp (T. Gunji).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.01.016

K.-i. Suyama et al. / Journal of Organometallic Chemistry 692 (2007) 2028–2035
2029
Due to the difficulty on the synthesis and instability
against the self-condensation of siloxanepolyols, the
X-ray crystallography studies are limited to the study of
the siloxanepolyols such as disiloxane-1,3-diols [R0Si-
(OH)2]2O (R0 = Ph [16], t-Bu [17], (t-BuO)3SiO [18], 2,
6-i-PrC6H3N(SiMe3) [19]) and cyclotetrasiloxane-1,3,5,7-
tetraols [R00Si(OH)O]4 (R00 = Ph [20], i-Pr [6]), which are
the target material for the study of supramolecular organo-
silicon compounds.
We have reported that sila-functional disiloxanes
[RSiX2]2O (R = Me, Vi, Ph, X = NCO, Cl) are selectively
synthesized by the vapor-phase hydrolysis of the trifunc-
tional silane RSiX3 [21] and also the reaction of the disilox-
anes with alcohols [22] or amines [16b] moderately
progresses to give partially substituted products. The
results revealed that isocyanatosilanes can be an appropri-
ate material to control the substitution reactions and/or to
prepare sila-functional oligosiloxanes such as iso-
cyanatodisiloxanes and disiloxanepolyols. We now report
the results for the synthesis and X-ray crystallography
study of the disiloxane-1,3-diols 1 and 2, and also the dis-
iloxane-1,1,3,3-tetraol 3 as shown:
Thermal gravimetric analyses of the disiloxanepolyols in
air showed that 1 and 2 melted at 79 ꢁC and 76 ꢁC, and
then rapidly vaporized above 145 ꢁC and 147 ꢁC, respec-
tively. In addition, the weight loss due to the condensation
of the silanol groups followed by water elimination was not
observed during the thermal gravimetry. On the other
hand, 3 showed a weight loss in the two stages from at
120–250 ꢁC due to thermal condensation (12%), and at
500–800 ꢁC due to the thermal decomposition of the con-
densed products (55%), which are almost identical to that
of silanetriol PhSi(OH)3: 100–200 ꢁC and 400–700 ꢁC [23].
Although the thermal condensation of 3 took place at the
same temperature as that of PhSi(OH)3, 3 was decomposed
at a higher temperature above 100 ꢁC compared to
PhSi(OH)3.
R
R
R
R
Me SiCl,Et N
3
3
t
-BuO Si O Si O
t-Bu
t
-BuO Si O Si O
t-Bu
OH OH
Me SiO OSiMe
3
3
1 ( R = Methyl )
2 ( R = Vinyl )
4 ( R = Methyl )
5 ( R = Vinyl )
ð3Þ
ð4Þ
OH
Si O Si
OH OH
OH
Me SiO
OSiMe
3
3
3
Me SiCl,Et N
3
3
Si O Si
Me SiO OSiMe
R
R
R
R
Et3N
2 H2O
t
-BuO Si O Si O
t
-Bu
t
-BuO Si O Si O
t-Bu
3
3
6
NCO NCO
OH OH
1 ( R = Methyl )
2 ( R = Vinyl )
In order to investigate the reactivity of the disiloxane-
ð1Þ
polyols, the reactions with Me3SiCl (Eqs. (3) and (4)) were
carried out in the presence of triethylamine as an HCl scav-
enger at room temperature or under reflux in THF and
monitored by gas chromatography. The reaction of 1 and
2 with Me3SiCl at room temperature gave a mixture of
mono- and di-substituted products. In contrast, the reac-
tion under reflux gave the corresponding di-substituted
products, the 3,5-di-t-butoxy-1,1,1,7,7,7-hexamethyl-3,5-
Cl
Si O Si
Cl Cl
Cl
OH
Si O Si
OH OH
OH
Aniline
4 H2O
3
ð2Þ
2. Results and discussion
2.1. Syntheses and properties of disiloxane-1,3-diol (1)
(R = Me), 2 (R = Vinyl), and disiloxane-1,1,3,3-tetraol (3)
di-R substituted tetrasiloxanes
4 (R = Me) and 5
(R = Vinyl), respectively, via the mono-substituted prod-
ucts. They were purified by distillation as a colorless liquid
in 80% yield for 4 (83–85 ꢁC/2.0 mmHg) and 70% yield for
5 (111–112 ꢁC/2.0 mmHg). Similarly, 3 gave 1,1,3,3-tetra-
trimethylsiloxy-1,3-diphenyldisiloxane 6 when all four
hydroxyl groups of 3 were silylated. Compound 6 was iso-
lated as a colorless liquid in 80% yield using Kugel–Rohr
distillation apparatus. Consequently, these results prove
that the disiloxanepolyols can be used as a building block
for the formation of novel siloxane compounds.
According to the literature [21], [MeSi(Ot-Bu)(NCO)]2O
and [ViSi(Ot-Bu)(NCO)]2O were synthesized by the vapor
phase hydrolysis of MeSi(NCO)3or ViSi(NCO)3 followed
by alcoholysis using t-butyl alcohol in the presence of trieth-
ylamine. The hydrolysis of [MeSi(t-OBu)(NCO)]2O and
[ViSi(Ot-Bu)(NCO)]2O in the presence of triethylamine in
THF followed by recrystallization of the hydrolyzate using
pentane produced the corresponding disiloxane-1,3-diols 1
and 2 as white solids in the yield of 78% and 63%, respectively
(Eq. (1)). The recrystallization of 1 and 2 by a solvent evap-
oration method using pentane produced a single crystal of a
colorless plate 1 and needle 2, respectively.
2.2. Crystal and molecular structure of 1,3-di-t-butoxy-1,3-
di-R substituted disiloxane-1,3-diols 1 (R = Me) and 2
(R = Vinyl)
The hydrolysis of [PhSiCl2]2O, which was synthesized by
the vapor phase hydrolysis of PhSiCl3, in the presence of
aniline in Et2O followed by recrystallization in Et2O/hex-
ane produced the 1,3-diphenyldisiloxane-1,1,3,3-tetraol 3
in 76% yield as a white solid (Eq. (2)).
The molecular structure of 1 is shown in Fig. 1. The
molecule 1 was crystallized in the triclinic system P1 with
two independent molecules in the asymmetric units with
ꢀ
a meso body. The average bond lengths and angles
˚
˚
were 1.63 A for Si–O(Si), 1.64 A for Si–O(H), 145.7ꢁ for

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K.-i. Suyama et al. / Journal of Organometallic Chemistry 692 (2007) 2028–2035
Fig. 3. Molecular structure of 2. Thermal ellipsoids shown at 50%
probability level. Hydrogen atoms are omitted for clarity.
Fig. 1. Molecular structure of 1. Thermal ellipsoids shown at 50%
probability level. Hydrogen atoms are omitted for clarity.
in conventional disiloxanepolyols [3]. The hydrogen-
bonded network structure and packing diagram of 2 are
shown in Fig. 4. Four independent molecules of 2 interact
with each other by the intermolecular hydrogen bonds
O(1)–O(8), O(2)–O(3), O(4)–O(5), and O(6)–O(7) to form
the chains which are further linked by hydrogen bonds
O(1)–O(3), O(2)–O(20), O(4)–O(8), O(5)–O(7), and O(6)–
O(60) to form the double chains as shown in Fig. 4a. All
the hydroxyl groups are used for the not intramolecular
bonds, but for the intermolecular hydrogen bonds. The
average O–O bond lengths in their hydrogen bonds were
Si–O–Si, and 105.0ꢁ for O–Si–O(H), respectively. These
bond lengths and angles are comparable to those found
in the conventional disiloxanepolyols [3]. The hydrogen-
bonded network structure and packing diagram of 1 are
shown in Fig. 2. Two independent molecules of 1 interact
with each other by the intermolecular hydrogen bonds
O(1)–O(4) and O(2)–O(3) to form the chains which are fur-
ther linked by hydrogen bonds O(1)–O(3), O(2)–O(20), and
O(4)–O(40) to form the double chains as shown in Fig. 2a.
All the hydroxyl groups were not used for the intramolec-
ular bonds but intermolecular hydrogen bonds. The aver-
age O–O bond lengths in their hydrogen bonds were
˚
2.68 A. This value is similar to that found in other disilox-
ane-1,3-diols [3]. As well as 1, the double chains, which are
formed by the ladder type hydrogen-bonded network, also
have a 1.21 nm diameter (calculated by the space-filling
model) columnar array; the surface layer of the column is
formed by the t-butyl and vinyl groups. The columns in
the crystal of 2 are packed in a pseudohexagonal mode
(Fig. 4b). There are no hydrogen bonds between the col-
umns. This crystal was, therefore, formed by the hydropho-
bic interaction between the organic groups.
The formation of the columnar array by the ladder-type
hydrogen-bonded network of the silanol groups have been
reported for [R2Si(OH)]2O (R = Me, Et, Pr, Ph) [3]. The
columnar array of these disiloxane-1,3-diols are also
packed in the pseudehexagonal mode. In these disiloxane-
1,3-diols, it was reported that the average O–O bond
lengths for the hydrogen bonds of [Et2Si(OH)]2O [9] and
˚
2.70 A. This value is similar to that found in the other dis-
iloxane-1,3-diols [3]. The double chains, which are formed
by a ladder type hydrogen-bonded network, form a
1.21 nm diameter (calculated by the space-filling model)
columnar array; the surface layer of the column is occupied
by the t-butyl and methyl groups. The columns in the crys-
tal of 1 are packed in the pseudohexagonal mode (Fig. 2b).
No hydrogen bonds are observed between the columns.
The crystal is, therefore, formed by the hydrophobic inter-
action between the organic groups.
The molecular structure of 2 is shown in Fig. 3. The
ꢀ
molecule 2 crystallizes in the triclinic system P1 with four
independent molecules in the asymmetric units with the
RR and SS body. The average bond lengths and angles
˚
˚
were 1.62 A for Si–O(Si), 1.63 A for Si–O(H), 151.5ꢁ for
Si–O–Si, and 105.6ꢁ for O–Si–O(H), respectively. These
bond lengths and angles are comparable to those found
˚
˚
[Pr2Si(OH)]2O [10] are 2.73 A and 2.70 A, respectively,
and the diameters of their columnar array are 1.06 nm
Fig. 2. Ladder like hydrogen-bonded structure with methyl and t-butoxy groups omitted for clarity (a) of disiloxane-1,3-diol 1 that are arranged to form
pseudo-hexagonal array with hydrogen atoms omitted for clarity (b). Dashed lines represent intermolecular hydrogen bonds.

K.-i. Suyama et al. / Journal of Organometallic Chemistry 692 (2007) 2028–2035
2031
Fig. 4. Ladder like hydrogen-bonded structure with vinyl and t-butoxy groups omitted for clarity (a) of disiloxane-1,3-diol (2) that are arranged to form
pseudo-hexagonal array with hydrogen atoms omitted for clarity (b). Dashed lines represent intermolecular hydrogen bonds.
and 1.26 nm, respectively. In contrast, the average O–O
clinic P21/n, respectively. The Si–O–Si bond angles of the
gauche-type and anti-type were 168.5ꢁ and 153.7ꢁ, respec-
tively. The average O–O bond lengths of their hydrogen
bond lengths for the hydrogen bonds of 1 and 2 are
˚
˚
2.70 A and 2.68 A, respectively, and both of the diameters
of their columnar array are 1.21 nm. Therefore, the size of
the columnar array is dependent of the substituents
attached to the silicon atoms rather than the strength of
the hydrogen bonds. [Et2Si(OH)]2O and [Pr2Si(OH)]2O
have been found to be a liquid crystal due to their crystal
structure. Thus far, the crystal structure of disiloxane-1,3-
diol with alkyl and alkoxy groups has not been reported.
The results that 1 and 2 form a columnar array as well as
the above 1,1,3,3-tetraalkyldisiloxane-1,3-diol can be an
interesting target for not only supramolecular organosil-
icon chemistry, but also liquid crystal chemistry.
˚
˚
bond were 2.72 A in the gauche-type and 2.68 A in the
anti-type. These values are similar to those found in other
disiloxane-1,1,3,3-tetraols [3,17,18]. The difference between
the gauche-type and anti-type is influenced by the difference
in the types of their hydrogen-bonded networks. All the
hydroxyl groups in both of them were used not as intramo-
lecular, but as intermolecular hydrogen bonds. In the case
of [t-BuSi(OH)2]2O, there are no intramolecular hydrogen
bonds and the Si–O–Si linkage becomes linear (bond angle
of Si–O–Si is 180ꢁ) [16]. In contrast, the molecular struc-
tures of [(t-BuO)3SiOSi(OH)2]2O [18] and [2,6-i-
PrC6H3N(SiMe3)Si(OH)2]2O [19] contain intramolecular
hydrogen bonds, which appear to distort the silicon–oxygen
backbone linkage into a parabolic shape, and their Si–O–Si
bonds are bent to 140ꢁ, respectively. The X-ray crystallog-
raphy additionally shows the difference in the molecular
array of the crystal between the gauche- and anti-types
and also between the disiloxane-1,3-diols 1 and 2.
The molecules of the gauche-type 3 are arranged in a
ladder shape along the b axis by the intermolecular hydro-
gen bonds O(1)–O(2) and O(3)–O(4), and the intermolecu-
lar p–p interaction between phenyl groups (Fig. 6a). The
ladder chains interact due to the hydrogen bond O(1)–
O(3) and O(4)–O(40) to form a columnar array (Fig. 6b)
which is further linked by the hydrogen bond O(2)–O(20)
in a parallel array; the surface layer of the column is occu-
pied by the phenyl groups (Fig. 6c and d). Consequently,
the crystal of the gauche-type is formed by the hydrogen
bond between the columns and the hydrophobic interac-
tion of the phenyl groups. As shown in Fig. 7a, the multiple
intermolecular hydrogen bonds are also present in the anti-
type 3, resulting in the molecular assembly into a sheet-like
structure in the ac plane in contrast to the columnar array
of the gauche-type. In this sheet, although the surface layer
is formed by the phenyl groups, there are no intermolecular
p–p interactions between the phenyl groups. Similarly,
2.3. Crystal and molecular structure of 1,3-
diphenyldisiloxane-1,1,3,3-tetraol (3)
Single crystals of 3 were obtained by recrystallization
with Et2O (a) and using the solvent evaporation method
with Et2O (b). As shown in Fig. 5, X-ray crystallography
of each crystal showed their conformations; the phenyl
groups are arranged in a gauche-conformation (a) and
anti-conformation (b). The space groups of the gauche-
and anti-types were found to be monoclinic C2/c and mono-
Fig. 5. Molecular structure of 3: (a) gauche type, (b) anti type. Thermal
ellipsoids are drawing at the 50% probability level. Hydrogen atoms are
omitted for clarity.

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K.-i. Suyama et al. / Journal of Organometallic Chemistry 692 (2007) 2028–2035
Fig. 6. Ladder like hydrogen-bonded structure (a) of gauche type 3 that are linked to form the columnar array (b) with phenyl groups are omitted for
clarity. The columnar array in a circle linked each other by O(2)–O(20) hydrogen bond (c) and formed the three-dimensional hydrogen-bonded network
(d): view down b axis, i.e. perpendicular to ac plane, Si, O, and C atoms are represented as cyan, red, and gray, respectively. Dashed lines represent
intermolecular hydrogen bonds. Hydrogen atoms are omitted for clarity. (For interpretation of the references to colour in this figure legend, the reader is
referred to the web version of this article.)
Fig. 7. The hydrogen-bonded structure of anti type 3 (a) with hydrogen atoms and phenyl groups are omitted for clarity that are linked to form the two-
dimensional wavy sheet (b): view down a axis, i.e. perpendicular to bc plane, Si, O, and C atoms are represented as cyan, red, and gray, respectively.
Dashed lines represent intermolecular hydrogen bonds. Hydrogen atoms are omitted for clarity. (For interpretation of the references to colour in this
figure legend, the reader is referred to the web version of this article.)
[t-BuSi(OH)2]2O with an anti-configuration was arranged
by the hydrogen bond to form a sheet-like structure [17].
Though the surface layer consists of t-butyl groups, there
are no interactions between the sheets. The sheets were flat
planes due to the linear Si–O–Si backbone linkage. How-
ever, the sheets formed by the anti-type 3 have a curvature
due to the bent Si–O–Si backbone linkage (Fig. 7b). In the
crystal of the anti-type 3, stacking of the overlapped phenyl
groups, but no hydrogen bonds between the sheets are
observed. As a result, the type of hydrogen bond in the
crystal of 3 varies with the conformation of the phenyl
groups which is affected by the recrystallization method.
No reports have been published that the conformation of
the disiloxane-1,1,3,3-tetraols varies with the recrystalliza-
tion method. This may be considered as follows: (a) in a
dilute solution of diethyl ether, a hydrophobic atmosphere,
molecules are assembled very slowly in the manner that the
hydrophobic groups surround the hydrophilic silanol
groups inside to form a columnar array. (b) In solvent
evaporation method, the fast crystallization and thereby
the formation of the hydrogen bonds preferentially pro-
ceeds before the inclusion of the hydrophilics by the
hydrophobics so that the molecules with an anti-configura-
tion consequently form a sheet-like molecular array.
3. Experimental
3.1. Reagents and general techniques
All chemicals were of reagent grade or higher and puri-
fied according to standard protocols. 1,1,3,3-Tetraiso-
cyanato-1,3-dimethyldisiloxane, 1,1,3,3-tetraisocyanato-1,

K.-i. Suyama et al. / Journal of Organometallic Chemistry 692 (2007) 2028–2035
2033
3-divinyldisiloxane,
and
1,1,3,3-tetrachloro-1,3-diph-
full-matrix least squares technique. The non-hydrogen
atoms were anisotropically refined and the hydrogen atoms
were placed in calculated positions and refined only for the
isotropic thermal factors. The crystal parameters and pro-
cedural information corresponding to the data collection
and structure refinement are given in Table 1. Figs. 6d
and 7b were created using VICS-II developed by R.A. Dil-
anian and F. Izumi.
enyldisi- loxane were prepared according to the literature
1
[21]. The H, 13C, and 29Si NMR spectra were recorded
using a JEOL ECP-500 (1H at 500.00 MHz, 13C at
125.00 MHz, and 29Si at 99.00 MHz) spectrometer. Chem-
ical shifts were reported as d units (ppm) relative to SiMe4,
and the residual solvent peaks were used as the standard.
The fourier transform infrared (FTIR) spectra were mea-
sured using a JEOL FT-IR-400 IR spectrophotometer
using the KBr disk method and CCl4 solution method.
The mass spectra (70 eV, EI) were obtained using a Shima-
dzu GCMS-QP2000A equipped with a direct insertion
apparatus. The mass spectra (FAB) were obtained on a
JEOL JMS-700 spectrometer. The thermal gravimetric
analyses were carried out with a 10 mg sample at the heat-
ing rate of 10 ꢁC/min in air using a TG-DTA 2000S from a
Bruker AXS. The silicon content was determined by the
following procedure: the weighed sample (0.2 g) was mixed
in a flask mixed with sulfuric acid (20 mL). Into this mix-
ture, ammonium sulfate (1 g) was added and gently heated
for 6 h. After cooling to room temperature, the content was
poured into ice in a beaker. After filtration using ashless
filter paper, the residue and filter paper were subjected to
firing in a crucible, then weighed as silica, SiO2.
3.3. Synthesis of 1,3-di-t-butoxy-1,3-diisocyanato-1,3-
dimethyldisiloxane
A solution of t-butyl alcohol (2.96 g, 0.04 mol) and tri-
ethylamine (0.40 g, 0.004 mol) in THF (50 mL) was slowly
added to a vigorously stirred and ice-cooled (0 ꢁC)
solution of 1,1,3,3-tetraisocyanato-1,3-dimethyldisiloxane
(5.43 g, 0.02 mol) in THF (30 mL). The reaction mixture
was refluxed for 2 h and filtered, followed by distillation
to give 1,3-di-t-butoxy-1,3-diisocyanato-1,3-dimethyldisil-
oxane (4.6 g, 70%). B.p. 92.0–92.5 ꢁC/2.0 mmHg; 1H
NMR (CDCl3) d 0.26 (s, 6H), 1.34 (m, 18H) ppm; 13C
NMR (CDCl3) d ꢀ0.40, 31.5, 74.8, 123.1 ppm; 29SiNMR
(CDCl3) d ꢀ62.3 ppm; MS (70 eV) m/z 317 (M+ꢀ15); IR
(CCl4): 2980, 2280, 1270, 1080 cmꢀ1
.
3.2. X-ray crystallography
3.4. Synthesis of 1,3-di-t-butoxy-1,3-diisocyanato-1,3-
divinyldisiloxane
A single crystal was attached to the top of a glass fiber
with a cold nitrogen gas stream at 90 K, and measured
using a Bruker SMART APEX equipped with a CCD dif-
fractometer (k(Mo Ka) = 0.71073 A, 25 2 ꢁC). The
structure was solved by SHELXL-97 [24] and refined by a
A solution of t-butyl alcohol (1.85 g, 0.025 mol) and tri-
ethylamine (0.20 g, 0.002 mol) in THF (50 mL) was added
to a vigorously stirred and ice-cooled (0 ꢁC) solution of
1,1,3,3-tetraisocyanato-1,3-divinyldisiloxane (2.94 g, 0.01
˚
Table 1
Crystallographic data for 1–3
Compound
1
2
3 (gauche)
3 (anti)
Formula
Mol. wt
C
282.49
10H26O5Si2
C12H26O5Si2
306.50
C12H14O5Si2
294.41
C12H26O5Si2
294.41
Temperature ꢁC
Crystal size (mm)
Crystal system
Space group
ꢀ180
ꢀ180
ꢀ180
ꢀ180
0.05 · 0.14 · 0.46
Triclinic
0.02 · 0.07 · 0.17
Triclinic
0.10 · 0.40 · 0.50
Monoclinic
C2/c
0.20 · 0.20 · 0.28
Monoclinic
P21/n
ꢀ
ꢀ
P1
P1
˚
a (A)
11.7896(9)
12.8225(10)
13.1771(11)
68.6310(10)
64.8450(10)
74.6440(10)
1664.8(2)
2
1.127
0.220
55.74
7830
12.0548 (15)
13.4814 (17)
23.070 (3)
99.754 (2)
90.093 (2)
107.879(2)
3510.9(9)
2
1.160
0.213
55.76
15781
30.6927(16)
4.9784(3)
19.7723(10)
6.1142(19)
21.376(7)
10.622(3)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
111.7520(10)
101.575(5)
3
˚
V (A )
2806.1(3)
8
1.394
0.265
56.62
3493
3175
176
1.081
0.0421
0.1259
1360.0(7)
4
1.438
0.273
56.46
3053
2507
172
1.033
0.0656
0.2022
Z
Dcalc (g mꢀ3
)
l (mmꢀ1
2hmax (ꢁ)
)
Number of reflections measured
Number of observed reflections
Number of parameters
S
6774
355
1.022
0.0373
8357
779
1.023
0.0624
R1 (I > 2r(I))
wR2 (all reflections)
0.1052
0.1774

2034
K.-i. Suyama et al. / Journal of Organometallic Chemistry 692 (2007) 2028–2035
mol) in THF (20 mL). The reaction mixture was refluxed
for 2 h and filtered, followed by distillation to give 1,3-
di-t-butoxy-1,3-diisocyanato-1,3-divinyldisiloxane (2.1 g,
59%). B.p. 100–102 ꢁC/2.0 mmHg; 1H NMR (CDCl3) d
1.30 (s, 18H), 5.89 (m, 4H), 6.10 (m, 4H) ppm; 13C NMR
(CDCl3) d ꢀ0.40, 31.5, 75.8, 123.1, 130.4, 136.5 ppm; 29Si
NMR (CDCl3)d ꢀ76.5 ppm; MS (70 eV) m/z 341
3.8. Synthesis of 3,5-di-t-butoxy-1,1,1,3,5,7,7,7-
octamethyltetrasiloxane (4)
A solution of Me3SiCl (2.72 g, 0.025 mol) in THF
(30 mL) was added to a rapidly stirred cold (0 ꢁC) solution
of 1 (2.82 g 0.01 mol) and triethylamine (2.53 g, 0.025 mol)
in THF (30 mL), and the mixture was refluxed for 1 h, fil-
tered, and evaporated to give the crude 4, followed by dis-
tillation to give 4 (3.40 g, 80%). B.p. 83.0–85.0 ꢁC/
2.0 mmHg; 1H NMR (CDCl3) d 0.04 (s, 6H), 0.10 (s,
18H), 1.27 (s, 18H) ppm; 13C NMR (CDCl3) d ꢀ1.2, 1.7,
31.7, 72.3 ppm; 29Si NMR (CDCl3) d 7.6, ꢀ64.0 ppm;
MS (FAB+) m/z = 427 [M+H]+. Exact mass: calcd for
C16H43O5Si4: 427.2188, Found 427.2205; IR (CCl4) 2975,
(M+ꢀ15); IR (CCl4) 2980, 2280, 1076, 1020 cmꢀ1
.
3.5. Synthesis of 1,3-di-t-butoxy-1,3-dimethyldisiloxane-1,3-
diol (1)
A solution of water (0.72 g, 0.04 mol) and triethylamine
(4.04 g, 0.04 mol) in THF (100 mL) was added to a rapidly
stirred cold (0 ꢁC) solution of 1,3-di-t-butoxy-1,3-diisocy-
anato-1,3-dimethyldisiloxane (6.64 g 0.02 mol) in THF
(30 mL), and the mixture was refluxed for 2 h, filtered,
and evaporated to give the crude 1. Recrystallization from
pentane (50 mL) afforded the pure 1 (4.3 g, 78%). M.p. 78–
79 ꢁC; 1H NMR (CDCl3) d 0.18 (s, 6H), 1.33 (s, 18H), 4.40
(br, 2H) ppm; 13C NMR (CDCl3) d ꢀ1.95, 31.6, 73.0 ppm;
29Si NMR (79.3 MHz, CDCl3) d ꢀ53.1 ppm; MS m/z =
267 (M+ꢀ15); IR (KBr) 3250, 2980, 1280, 1060,
1020 cmꢀ1. Anal. Calc. for C10H26O5Si2: Si, 19.9. Found:
Si, 19.9%.
1549, 1252, 1204, 1061 cmꢀ1
.
3.9. Synthesis of 3,5-di-t-butoxy-1,1,1,7,7,7-hexamethyl-3,5-
divinyltetrasiloxane (5)
A solution of Me3SiCl (2.72 g, 0.025 mol) in THF
(30 mL) was added to a rapidly stirred cold (0 ꢁC) solu-
tion of 2 (3.06 g 0.01 mol) and triethylamine (2.53 g,
0.025 mol) in THF (30 mL), and the mixture was
refluxed for 1 h, filtered, and evaporated to give the
crude 5, followed by distillation to give 5 (3.15 g, 70%).
B.p. 111–112 ꢁC/2.0 mmHg; 1H NMR (CDCl3) d 0.12
(s, 18H), 1.29 (s, 18H), 5.89–5.93 (m, 6) ppm; 13C
NMR (CDCl3) d 1.7, 31.7, 72.5, 133.6, 134.5 ppm; 29Si
NMR (CDCl3) d 8.3, ꢀ79.1 ppm; MS (FAB+) m/z =
451 [M+H]+. Exact mass: calcd for C18H43O5Si4
451.2188, Found: 451.2174; IR (CCl4) 2976, 1549, 1404,
3.6. Syntheses of 1,3-di-t-butoxy-1,3-divinyldisiloxane-1,3-
diol (2)
A solution of water (0.90 g, 0.05 mol) and triethylamine
(5.05 g, 0.05 mol) in THF (100 mL) was added to a rapidly
stirred cold (0 ꢁC) solution of 1,3-di-t-butoxy-1,3-diisocy-
anato-1,3-divinyldisiloxane (8.90 g 0.025 mol) in THF
(30 mL), and the mixture was refluxed for 2 h, filtered,
and evaporated to give the crude 2. Recrystallization from
hexane (50 mL) afforded the pure 2 (4.9 g, 63%). M.p. 76–
78 ꢁC; 1H NMR (CDCl3) d 1.33 (s, 18H), 3.84 (s, 2H), 5.97
(m, 4H), 6.10 (m, 2H) ppm; 13C NMR (CDCl3) d 31.7,
73.6, 132.7, 135.4 ppm; 29Si NMR (CDCl3)d ꢀ67.9 ppm;
MS m/z = 294 (M+ꢀ15); IR (KBr) 3220, 2977, 1241,
1062, 964 cmꢀ1. Anal. Calc. for C12H26O5Si2: Si, 18.3.
Found: Si, 18.5%.
1365, 1251, 1202, 1066 cmꢀ1
.
3.10. Synthesis of 1,1,3,3-hexanmethyl-3,5-diphenyl-3,5-
bis(trimethylsiloxy)tetrasiloxane (6)
A solution of Me3SiCl (5.44 g, 0.05 mol) in THF
(30 mL) was added to a rapidly stirred cold (0 ꢁC) solution
of 3 (2.94 g 0.01 mol) and triethylamine (5.06 g, 0.05 mol)
in THF (30 mL), and the mixture was refluxed for 1 h, fil-
tered, and evaporated to give the crude 6, followed by dis-
tillation to give 6 (5.1 g, 89%). 1H NMR (CDCl3) d 0.13 (s,
18 H), 7.33–7.68 (m, 5H) ppm; 13C NMR (CDCl3) d 1.7,
127–134.9 ppm; 29Si NMR (CDCl3) d 9.6, ꢀ79.2 ppm;
MS (FAB+) m/z = 582 [M]+. Exact mass: calcd for
C24H46O5Si6: 582.1961, Found 582.1957; IR (CCl4) 3074,
3.7. Synthesis of 1,3-diphenyldisiloxane-1,1,3,3-tetrol (3)
A solution of 1,1,3,3-tetrachloro-1,3-diphenyldisiloxane
(7.36 g, 0.02 mol) in diethyl ether (40 mL) was added to a
suspension of water (1.44 g, 0.08 mol) and aniline (7.44 g,
0.08 mol) while stirring at 0 ꢁC and kept for 1 h. The reac-
tion mixture was filtered to remove the aniline hydrochlo-
ride. Recrystallization of the filtrate from hexane (40 mL)
afforded 3 (4.5 g, 76%). M.p. 114–115 ꢁC; 1H NMR
(CDCl3) d 5.81 (br, 4H), 7.20–7.72 (m, 10H) ppm; 13C
NMR (CDCl3) d 127.7, 129.7, 135.1, 136.9 ppm; 29Si
NMR (CDCl3) d ꢀ62.1 ppm; IR (KBr) 3200, 1429, 1110,
911 cmꢀ1. Anal. Calc. for C12H14O5Si2: Si, 19.0. Found:
Si, 19.1%.
2959, 1429, 1252, 1132, 1059, 845 cmꢀ1
.
Acknowledgements
We are grateful to N. Igarashi, K. Kitajima, and K.
Yoza (Bruker AXS) for their assistance with the X-ray
crystallography. This work was supported by the High-
Tech Research Center Project for Private Universities
and a matching fund subsidy from MEXT (Ministry of
Education, Culture, Sports, Science and Technology),
2002–2006.

K.-i. Suyama et al. / Journal of Organometallic Chemistry 692 (2007) 2028–2035
2035
(c) G. Prabusankar, R. Murugavel, R.J. Butcher, Organometallics 23
(2004) 2305.
Appendix A. Supplementary material
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CCDC 630785, 630786, 236204, and 630787 contain the
supplementary crystallographic data for 1, 2, gauche-3,
anti-3. These data can be obtained free of charge via
http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from
the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-
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