Facile syntheses, structural characterizations, and isomerization of disiloxane-1,3-diols

Article abstract of DOI:10.1016/j.jorganchem.2003.10.030

In the hydrolysis reaction of dichlorosilanes having an intramolecular coordinating atom, dcisiloxane-1,3-diols, [(OH){o-(CH₃) ₂NCH₂-C₆H₄}RSi]₂ O(R=CH₂=CH (1), C₆H

Full text of DOI:10.1016/j.jorganchem.2003.10.030

Journal of Organometallic Chemistry 689 (2004) 471–477
www.elsevier.com/locate/jorganchem
Facile syntheses, structural characterizations,
and isomerization of disiloxane-1,3-diols
Hyeon Mo Cho, Sea Ho Jeon, Han Kuk Lee, Jung Hoon Kim,
*
*
Sangwoo Park, Moon-Gun Choi , Myong Euy Lee
Department of Chemistry, Graduate School, Yonsei University, Seoul 120-749, Republic of Korea
Received 23 July 2003; accepted 7 October 2003
Abstract
In the hydrolysis reaction of dichlorosilanes having an intramolecular coordinating atom, disiloxane-1,3-diols, [(OH)
{o-(CH3)2NCH2-C6H4}RSi]2O (R ¼ CH2@CH (1), C6H5 (2), o-(CH3)2NCH2C6H4 (3), Me (4)), were obtained in high yields. The
results of the crystal structure analyses of meso-2, rac-2a, rac-2b and 3 are reported. They showed strong intramolecular hydrogen
bondings between the hydroxy group and the nitrogen atom. We have also found that the diastereomeric isomerization of meso-2 to
rac-2 in CDCl3 solvent containing moisture occurred to result in the 55:45 equilibrium mixtures of the isomers and vice versa.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Silanol; Disilanol; Intramolecular hydrogen bonding; Diastereomer
1. Introduction
solvent, and substituent should be considered. For ex-
ample, O(Ph2SiOH)2 was synthesized using pH con-
trolled hydrolysis of Ph2SiCl2 [7]. The reaction of
dichlorodiphenylsilane (1.0 mol) with water (108 mol)
and ammonium carbonate (1.4 mol) for 2.5 h gave
diphenylsilanediol, while the mixture of dichlorodiphe-
nylsilane (1.5 mol), water (1.5 mol), and ammonium
carbonate (2.1 mol) in diethylether was heated at reflux
for 12 h to yield tetraphenyldisiloxane-1,3-diol and
hexaphenyltrisiloxane-1,5-diol. Recently, we synthesized
the diastereomeric disiloxane-1,3-diols, 1,3-dihydroxy-
1,3-bis[2-(dimethylaminomethyl)phenyl]-1,3-divinyldisil-
oxanes, 1, in high yield from the hydrolysis reaction
of [2-(dimethylaminomethyl)phenyl]vinyldichlorosilane
having an intramolecular coordinating arm [8]. In an
extension of this work, we have investigated a new
synthetic method of disiloxane-1,3-diols devoid of usual
tedious processes. An introduction of intramolecular
donor atom provides a convenient way to synthesize
disiloxane-1,3-diols. In the hydrolysis reaction of di-
chlorosilanes having intramolecular coordinating atoms,
silanediols might be formed first as an intermediate,
which could be partially condensed to give disiloxane-
1,3-diols because of the enhancement of the reactivity of
Disiloxane-1,3-diols are known as primary sources
for the support of metal complexes within metal-
lasiloxanes, and for the preparation of polysiloxanes
and heterosiloxanes [1]. A variety of disiloxane-1,3-diols
of general formula (OHR2Si)2O (R ¼ Me [2], Et [3],
Pr [4], Bu [4,5] or Ph [6]) have been synthesized and
structurally investigated. The simplest disiloxane-1,3-
diol, (OHMe2Si)2O, is one of the basic units from which
polydimethylsiloxanes are built.
The syntheses of disiloxane-1,3-diols are not easy
because of their tendency to undergo further conden-
sation to polysiloxanes or the tendency not to be con-
densed from silanediols because of the size or the
electronic effect of substituents at silicon atom [1b].
Many trials and errors are needed to obtain disiloxane-
1,3-diols without silanediols and without further con-
densed silanols. Various reaction conditions such as
reaction temperature, reaction time, hydrolysis reagent,
* Corresponding authors. Fax: +82-33-760-2182.
E-mail addresses: choim@yonsei.ac.kr (M.-G. Choi), melee@
dragon.yonsei.ac.kr (M.E. Lee).
0022-328X/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.10.030

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H.M. Cho et al. / Journal of Organometallic Chemistry 689 (2004) 471–477
[O(Si(ferrocenyl)2OH)2] [11], 5.67 ppm [Cp*Si(OH)3]
[12], and 4.30–5.30 ppm (aminosilanetriols) [13].
The reaction of bis[2-(dimethylaminomethyl)phen-
yl]dichlorosilane [10,14] with 2 equiv of water in the
presence of triethylamine at room temperature for 1 h
gave 1,3-dihydroxy-1,1,3,3-tetrakis[2-(dimethylaminom-
ethyl)phenyl]disiloxane, 3, to be recrystallized from n-
hexane. The 1H NMR resonance of hydroxy group for 3
was observed at 9.98 ppm. The similar reaction was
carried out in the absence of an acid acceptor by Auner
et al. [15] to give disiloxane-1,3-diolÕs salt, 3 ꢀ 2HCl re-
crystallized from n-pentane. Belzner [16] also synthe-
Scheme 1.
the hydroxy group opposite to donor atoms caused by
the intramolecular electron donation from donor atoms
to silicon (Scheme 1) [9].
Herein, we report on the syntheses, detailed structural
characterizations, and the water-induced diastereomeric
isomerization of [(OH)o-(CH3)2NCH2-C6H4RSi]2O (R¼
C6H5 (2), o-(CH3)2NCH2C6H4 (3), Me (4)).
Table 1
1H NMR of OH (CDCl3, ppm, rt)
meso-1
rac-1
meso-2
rac-2
3
4
OH
9.90
9.98
10.37
10.37
9.98
9.53
2. Results and discussion
2.1. Syntheses of 2, 3 and 4
An introduction of (dimethylaminomethyl)phenyl
group into the silicon center was achieved by the reaction
of ortho-lithiated (dimethylaminomethyl)phenyl with Cl3
RSi. The reaction of [2-(dimethylaminomethyl)phenyl]
phenyldichlorosilane [10] with 2 equiv of water in the
presence of triethylamine, as an acid acceptor, at room
temperature for 1 h afforded diastereomeric isomers, 1,
3-dihydroxy-1,3-bis[2-(dimethylaminomethyl)phenyl]-1,
3-diphenyldisiloxane, 2, as crystalline in 72% isolated
yield. Meso-2 was recrystallized from diethylether at
room temperature. Interestingly, rac-2a was recrystal-
lized from the mixture of n-hexane and methylenechloride
at room temperature, and rac-2b, which is the confor-
mational isomer of rac-2a, was recrystallized from di-
ethylether at )30 °C (Scheme 2).
1
In the H NMR spectra of 2, the broad proton ab-
sorption of the hydroxy group resonated at 10.37 ppm
similar to those (9.98 and 9.90 ppm) of diastereomeric
isomers, 1. This data indicates that 2 has a very strong
intramolecular hydrogen bonding in solution. In con-
trast, the 1H NMR resonance of OH for silanols having
intermolecular hydrogen bonding appeared at 2.66 ppm
OH
R
N
2 H2O / 2 Et3N
Et2O, 0 oC - rt
N
O
Cl
R
Si
Si
Si
Cl
N
R
OH
1, 78%, R = vinyl [8]
2, 72%, R = phenyl
3, 65%, R = dimethylaminomethylphenyl
4, 68%, R = methyl
Fig. 1. ORTEP drawing of meso-2, showing with 30% thermal ellip-
soids. H atoms are omitted for clarity.
Scheme 2. Syntheses of 1–4.

H.M. Cho et al. / Journal of Organometallic Chemistry 689 (2004) 471–477
473
Fig. 2. ORTEP drawing of rac-2a, showing with 30% thermal ellip-
soids. H atoms are omitted for clarity.
Fig. 3. ORTEP drawing of rac-2b, showing with 30% thermal ellip-
soids. H atoms are omitted for clarity.
sized compound 3 using a different method of the hy-
drolysis of hexakis[(2-dimethylaminomethyl)phenyl]cy-
clotrisilane. In manners similar to the synthesis of 2 and
3, diastereomeric 1,3-dihydroxy-1,3-bis[2-(dimethylami-
nomethyl)phenyl]-1,3-dimethyl-disiloxanes, 4 were ob-
tained as colorless oil. We were unable to separate
isomers (60:40) because of isomerization between them
in liquid state. The 1H NMR resonance of hydroxy
group for 4 was observed at 9.53 ppm. The OH reso-
nances of 2, 3, and 4 were not dependent on the con-
centration of solution in CDCl3 (Table 1).
2.2. X-ray structures of 2 and 3
X-ray crystallographic analyses of 2 and 3 reveal their
structures, as shown in Figs. 1–4. The Si–O–Si angles
(152°–159°) of 2 are similar to those of simple disilox-
i
ane-1,3-diols, O(SiR2OH)2 (R ¼ Me [17], Et [18], Pr
[19], Phenyl [20]), whose Si–O–Si angles are in the range
of 141°–163° (Tables 2 and 3). But the Si–O–Si angle of
Fig. 4. ORTEP drawing of 3, showing with 30% thermal ellipsoids. H
atoms are omitted for clarity.

474
H.M. Cho et al. / Journal of Organometallic Chemistry 689 (2004) 471–477
Table 2
Crystal data and structure refinement for meso-2, rac-2a and rac-2b
Table 3
Crystal data and structure refinement for 3
meso-2
rac-2a
rac-2b
3
Empirical
formula
C30H36N2O3Si2
Empirical formula
Formula weight
Temperature (K)
C36H50N4O3Si2
642.98
298(2)
0.71069
Formula weight
Temperature (K)
528.79
233(2)
ꢀ
Wavelength (A)
ꢀ
Wavelength (A)
0.71073
triclinic
Crystal system
Space group
triclinic
ꢁ
Crystal system
Space group
triclinic
ꢁ
orthorhombic
Iba2
P1
ꢁ
P1
P1
Unit cell dimensions
ꢀ
Unit cell dimensions
ꢀ
a (A)
9.3020(10)
13.878(2)
15.505(2)
106.40(2)
100.200(10)
93.020
ꢀ
a (A)
9.5536(19)
9.931(2)
15.931(3)
86.994(4)
86.635(4)
76.943(4)
1468.8(5)
2
9.2917(8)
11.1847(9)
14.6458(12)
81.124(2)
84.490(2)
85.139(2)
1493.1(2)
2
19.212(9)
8.985(4)
16.867(8)
90
b (A)
ꢀ
ꢀ
b (A)
c (A)
ꢀ
c (A)
a (°)
b (°)
c (°)
a (°)
b (°)
c (°)
90
90
3
ꢀ
Volume (A )
1878.6(4)
2
1.137
3
ꢀ
Volume (A )
2912(2)
4
1.206
Z
Z
Calculated density (Mg/m3)
Calculated
density (Mg/m3)
Absolute
1.196
1.176
Absolute coefficient (mmꢁ1
)
0.132
692
F ð000Þ
0.153
0.151
0.154
Crystal size (mm3)
h range for data collection (°)
Index ranges
0.73 ꢂ 0.58 ꢂ 0.41
1.54–27.50
ꢁ12 6 h 6 10, ꢁ18 6 k 6 17,
0 6 l 6 20
coefficient
(mmꢁ1
)
F ð000Þ
564
Crystal size (mm3) 0.52 ꢂ 0.24
ꢂ 0.18
564
0.58 ꢂ 0.07
ꢂ 0.05
1128
0.62 ꢂ 0.52
ꢂ 0.38
Number of reflections collected 8546
Number of independent 8546 (0.0000)
reflections (Rint
Completeness to hmax (%)
Refinement method
Number of data/restraints/
parameters
Goodness-of-fit on F 2
Final R indices [I > 2rðIÞ]
R indices (all data)
h range for data
collection (°)
Index ranges
1.28–25.54
1.41–20.00
2.12–25.52
)
99.1
full-matrix least-squares on F 2
8546/0/412
ꢁ11 6 h 6 11, ꢁ8 6 h 6 8,
ꢁ10 6 k 6 12, ꢁ10 6 k 6 9,
ꢁ22 6 h 6 23,
ꢁ10 6 k 6 10,
ꢁ19 6 l 6 17
ꢁ14 6 l 6 12 ꢁ10 6 l 6 20
Number of
reflections
collected
7878
5102
7330
1.125
R1 ¼ 0:0964, wR2 ¼ 0:1710
R1 ¼ 0:1906, wR2 ¼ 0:2271
Number of
independent
reflections (Rint
Completeness to
hmax (%)
5418 (0.0281) 2753 (0.0678) 2051 (0.0614)
Table 4
Selected bond distances (A) and angles (°) for compounds 2 and 3
)
ꢀ
98.7
99.0
100.0
meso-2
rac-2a
rac-2b
3
Refinement
method
full-matrix least-squares on F 2
Si–O of Si–O–Si 1.626(2)
1.620(2)
1.618(3)
1.610(3)
1.612(4)
1.612(4)
159.3(2)
2.661(6)
2.696(7)
166(6)
1.6224(13)
1.617(3)
1.624(3)
1.622(3)
1.620(4)
174.4(2)
2.646(5)
2.731(5)
171(6)
Number of
data/restraints/
parameters
Goodness-of-fit
on F 2
Final R indices
[I > 2rðIÞ]
R indices
5418/1/342
2753/0/478
1.021
2051/1/172
1.032
Si–O of Si–OH 1.608(2)
1.617(2)
1.618(3)
Si–O–Si
N–O
152.27(14)
2.692(3)
2.745(3)
172(3)
152.1(2)
2.651(4)
0.859
R1 ¼ 0:0478,
R1 ¼ 0:0581, R1 ¼ 0:0484,
N–H–O
H–O
175(5)
wR2 ¼ 0:1001 wR2 ¼ 0:1282 wR2 ¼ 0:1216
163(3)
1.817(18)
1.82(3)
160(5)
1.89(5)
1.92(5)
172(6)
1.89(6)
1.92(6)
R1 ¼ 0:1250,
R1 ¼ 0:0937, R1 ¼ 0:0528,
1.69(6)
(all data)
wR2 ¼ 0:1319 wR2 ¼ 0:1505 wR2 ¼ 0:1247
3 is larger (174.4(2)°). The selected bond distances and
angles are listed in Table 4. Noteworthy in the structures
of 2 and 3 is the strong intramolecular hydrogen
bonding between the hydroxy group and nitrogen atom,
in contrast to the intermolecular hydrogen bonding of
known disiloxane-1,3-diols [17–21]. In meso-2, the O(2)–
H(1)–N(1) angle is 172(3)°; the N(1)–H distance is
of rac-2 and 3 are in the range of the normal hydrogen
bonding distance.
2.3. Isomerization of 2
We observed that the diastereomeric isomerization
of meso-2 in non-dried CDCl3 solvent occurred to re-
sult in the 55:45 equilibrium mixture of meso-2 and rac-
ꢀ
ꢀ
1.817(18) A and the N(1)–O(2) distance 2.692(3) A,
1
which is within the normal distance for hydrogen
ꢀ
bonding (2.62–2.93 A) [22]. Similarly, the N–O distances
2 and vice versa, which was monitored by H NMR, as
was the case for isomerization of meso-1 to rac-1 [8].

H.M. Cho et al. / Journal of Organometallic Chemistry 689 (2004) 471–477
475
AP
Si
H2O
(trace in CDCl3)
4.2. Synthesis of 2
AP
AP
Ph
OH
OH
HO
HO
Ph
Ph
To a mixture of H2O (1.8 ml, 0.10 mol) and triethyl-
amine (14 ml, 0.10 mol) in Et2O was added slowly [2-
(dimethylaminomethyl)phenyl]phenyldichlorosilane (15
g, 0.049 mol) in Et2O at 0 °C during 50 min. The reaction
mixture was allowed to warm slowly to room tempera-
ture and stirred for 1 h. After filtration of the precipitated
Et3NHCl, volatiles were distilled under vacuum. The
residue was recrystallized to give meso-2 and rac-2 (55:45)
as colorless crystals (9.3 g, 72%). Meso-2: m.p.: 137–138
°C. 1H NMR (CDCl3, 500 MHz): d 2.13 (s, 12H,
Si
dry CDCl3
Ph
meso-2
AP
(AP= dimethylaminomethylphenyl)
rac-2
Fig. 5. Isomerization of 2.
On the other hand, in dry CDCl3, meso-2 or rac-2 was
stereochemically rigid and did not isomerize (Fig. 5).
An isotope experiment using H128O was conducted in
order to prove the mechanism of the isomerization. The
isomerization of meso-2 in the presence of H128O oc-
curred to give partly 18O labeled disiloxane-1,3-diol
identified by FAB MS. This indicates that meso-2
isomerization is induced by nucleophilic attack by wa-
ter at silicon. It is rare that the hydrolysis of silanol
occurred by water under a neutral condition in the
absence of a base or an acid. The detailed discussion
about the isomerization of silanol was reported in our
previous paper [8].
2
N(CH3)2), 3.23, 3.62 (AB-system, J(H, H) ¼ 12.4 Hz,
4H, PhCH2), 7.08–7.73 (m, 18H, C6H4, C6H5), 10.37 (s,
2H, OH). 13C NMR (CDCl3, 125 MHz): d 43.93 (NMe2),
64.65 (CH2N), 126.97, 127.51, 129.35, 129.62, 130.81,
134.78, 135.66, 136.27, 137.82, 142.06 (C6H4, C6H5). IR
(film, cmꢁ1, KBr): 3420 (OH), 1094 (Si–O–Si). Anal.
Calc. for C30H36N2O3Si2: C, 68.14; H, 6.86; N, 5.30.
Found: C, 68.17; H, 6.86; N, 5.34. Rac-2: m.p.: 145–146
°C. 1H NMR (CDCl3, 500 MHz): d 2.20 (s, 12H,
2
N(CH3)2), 3.17, 3.52 (AB-system, J(H, H) ¼ 12.4 Hz,
4H, PhCH2), 7.07–7.72 (m, 18H, C6 H4, C6H5), 10.37 (s,
2H, OH). 13C NMR (CDCl3, 125 MHz): d 43.83 (NMe2),
64.58 (CH2N), 126.94, 127.48, 129.34, 129.56, 130.74,
134.68, 135.67, 136.23, 137.77, 142.06 (C6H4, C6H5). IR
(film, cmꢁ1, KBr): 3420 (OH), 1094 (Si–O–Si).
3. Conclusion
In this work, we have observed that an introduction
of intramolecular donor atom provided a convenient
way to synthesize disiloxane-1,3-diols, [(OH)o-
{(CH3)2NCH2-C6H4}RSi]2O (R ¼ CH2@CH (1) C6H5
(2), o-{(CH3)2NCH2}C6H4 (3), Me (4)), in high yields.
In the structural studies of meso-2, rac-2a, rac-2b and 3,
we found strong intramolecular hydrogen bondings
between the hydroxy group and the nitrogen atom,
which is consistent with the 1H NMR resonances of
hydroxyl groups observed at down fields. We have also
observed that the diastereomeric isomerization of meso-
2 in CDCl3 solvent containing moisture occurred to
result in the 55:45 equilibrium mixtures of meso-2 and
rac-2, as was the case for the isomerization of meso-1 to
rac-1.
4.3. Synthesis of 3
To a mixture of H2O (0.11 ml, 6.1 mmol) and tri-
ethylamine (0.90 ml, 6.5 mmol) in Et2O was added
slowly bis[2-(dimethylaminomethyl)phenyl]dichlorosi-
lane (1.10 g, 3.0 mmol) in Et2O at 0 °C. In similar
manners to synthesis of 2, 3 as colorless crystals was
1
obtained in 65% yield (0.63 g). 3: m.p.: 111–112 °C. H
NMR (CDCl3, 500 MHz): d 2.20 (s, 24H, NMe2), 3.32,
3.58 (AB-system, 2J(H, H) ¼ 13.0 Hz, 8H, PhCH2),
7.12–7.76 (m, 16H, C6H4), 9.98 (s, 2H, OH). 13C NMR
(CDCl3, 125 MHz): d 41.1 (NMe2), 61.1 (PhCH2),
126.6, 128.6, 129.5,133.5, 135.5, 143.6 (C6 H4). Anal.
Calc. for C36H50N4O3Si2: C, 67.25; H, 7.84; N, 8.71.
Found: C, 67.25; H, 7.79; N, 8.68%.
4. Experimental
4.4. Synthesis of 4
4.1. General comments
To a mixture of H2O (0.11 ml, 6.1 mmol) and triethyl-
amine (0.85 ml, 6.1 mmol) in Et2O was added slowly [2-
(dimethylaminomethyl)phenyl]methyldichlorosilane [23]
(0.74 g, 3.0 mmol) in Et2O at 0 °C. In similar manners to
synthesis of 2, 4 was obtained in 68% yield (0.41 g). 4: 1H
NMR (CDCl3, 500 MHz): d 0.27, 0.30 (s, 6H, SiCH3),
2.05, 2.06 (s, 12H, NMe2), 3.06–3.66, 3.06–3.71 (m, 4H,
PhCH2), 7.01–7.55 (m, 8H, C6H4), 9.53 (s, 2H, OH).
13C NMR (CDCl3, 125 MHz): d )1.34, )1.32 (SiCH3),
43.91 (NMe2), 64.65, 64.66 (PhCH2), 127.0, 129.2, 130.8,
In all reactions where air-sensitive chemicals were
used, the reagents and solvents were dried prior to use.
Diethylether was distilled from Na/Ph2CO. Other
starting materials were purchased in reagent grade and
used without further purification. 1H and 13C NMR
spectra were recorded on a Bruker DPX 250 FT-NMR
spectrometer and Bruker AMX 500 NMR spectrometer
and referenced to residual protons of the solvent with
chemical shifts being reported as d ppm.

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H.M. Cho et al. / Journal of Organometallic Chemistry 689 (2004) 471–477
134.8, 134.9, 139.2, 141.7 (C6H4). Anal. Calc. for
C20H32N2O3Si2: C, 59.36; H, 7.97; N, 6.92. Found: C,
59.32; H, 8.02; N, 6.90%.
5. Supplementary material
Crystallographic data for the structure analyses have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 215352 for compound meso-2,
No. 215353 for compound rac-2a, No. 215354 for com-
pound rac-2b, and No. 215355 for compound 3. Copies of
this information may be obtained from the Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax:
+44-1233-336033; e-mail: deposit@ccdc.cam.ac.uk or
www: http://www.ccdc.cam.ac.uk).
4.5. Isomerization of 2 in the presence of H128O
To meso-2 (30 mg) in 1.0 ml of CDCl3 in an NMR tube
was added 3.0 ll of H128O at room temperature. The
isomerization of meso-2 to rac-2 was monitored by H
1
NMR spectroscopy. It took about 10 days to reach the
equilibrium (55:45). The partly 18O labeled disiloxane-
1,3-diol 2 was identified by FAB-MS and compared with
the FAB-MS of meso-2. FAB-MS: m=z (relative intensity)
18O labeled 2: 528 (100), 530 (55); meso-2: 528 (100), 530
(22).
Acknowledgements
This work was supported by Korea Research Foun-
dation (KRF-2000-BSRI DP0228), a postdoctoral grant
(2002) to Hyeon Mo Cho from Natural Science Re-
search Institute, Yonsei University. We are also grateful
to Professor Uk Lee (Pukyong National University) for
crystallographic analyses.
4.6. Crystallographic experimental section
Crystals (compound 2) were selected and attached to
the tip of a glass fiber, transferred to a Bruker SMART
diffractometer/CCD area detector and centered under
liquid nitrogen in the beam at 233(2) K. The crystal
evaluation and data collection were performed on a
Bruker CCD diffractometer with Mo Ka (k ¼ 0:71073
References
ꢀ
A) radiation employing 2 kW sealed tube X-ray source
operating at 1.6 kW and the diffractometer to crystal
distance of 4.9701 cm. Preliminary orientation matrix
and cell constants were determined from three series of
x scans at different starting angles. Each series consisted
of 10 frames collected at intervals of 0.3° x scan with
the exposure time of 10 s per frame. A single crystal
(compound 3) was used for data collections on a
STOE STADI4 four-circles-diffractometer with graphite
monochromatized Mo Ka radiation at room tempera-
ture. Cell parameters and an orientation matrix for data
collections were obtained from least-squares refinement,
using the 36 reflections in 19:0 < 2h < 21:5. Intensities
were collected x–2h scan technique. During data col-
lection three standard reflections were measured every
hour and showed no significant. The intensity data were
collected for Lorentz and polarization effect, and ab-
sorption correction was not applied.
[1] (a) For a review on disiloxane-1,3-diols, see: R. Murugavel, A.
Voigt, M.G. Walawalkar, H.W. Roesky, Chem. Rev. 96 (1996)
2205;
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