Synthesis and structure of 1,3-bis(hydroxysilyl)-2,4-dimethyl-2,4- diphenylcyclodisilazane

Article abstract of DOI:10.1016/j.jorganchem.2011.07.002

Trans-silylation reactions of (Me₃Si)₂NH with PhRSiCl₂ (R = Me, Ph) gave HN(SiMePhCl)₂ (1) or ClMePhSiNHSiPh₂Cl (2). The treatment of 1,3-dichlorodisilazane (1 or 2) with an equimolar amount of n-BuLi

Full text of DOI:10.1016/j.jorganchem.2011.07.002

Journal of Organometallic Chemistry 696 (2011) 3245e3250
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Synthesis and structure of 1,3-bis(hydroxysilyl)-2,4-dimethyl-2,
4-diphenylcyclodisilazane
,
,
Yan Zheng a b, Yongxia Tan a, Lina Dai a, Zhijie Zhang a
*
a Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
b Graduate School of Chinese Academy of Sciences, Beijing 100049, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Trans-silylation reactions of (Me3Si)2NH with PhRSiCl2 (R ¼ Me, Ph) gave HN(SiMePhCl)2 (1) or ClMePh-
SiNHSiPh2Cl (2). The treatment of 1,3-dichlorodisilazane (1 or 2) with an equimolar amount of n-BuLi led
to the formation of 1,3-bis(chloro-silyl)-2,4-dimethyl-2,4-diphenylcyclodisilazane (ClSiMePh)2(NSiMePh)2
(3) or (ClSiPh2)2(NSiMePh)2 (4), which was allowed to hydrolyze to form 1,3-bis(hydroxysilyl)-2,4-
dimethyl-2,4-diphenylcyclodisilazane (HOSiMePh)2(NSiMePh)2 (5) or (HOSiPh2)2(NSiMePh)2 (6), respec-
tively. The cyclodisilazane monomers were characterized by elemental analysis, NMR and IR spectroscopy.
Compound 3 was obtained as a 4:6 cis/trans mixture while 4 adopted trans-structure considering the
hindrance of pendent groups. In addition, the molecular structures of trans-5 and trans-6 were determined
by X-ray crystallographic analysis and discussed in detail.
Received 15 April 2011
Received in revised form
27 June 2011
Accepted 5 July 2011
Keywords:
Cyclodisilazane
Mixed phenyl
Crystal structure
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
absorption as indication of the presence of Si4N2 skeleton. However,
no further evidence was described and its molecular structure
Owing to their specific structural features, N-silyl-substituted
cyclodisilazanes have attracted increasing attention as potential
complements to silicone rubber in high-temperature applications
[1e6]. Despite their striking thermal stability, few reports deal with
such applications due to the inherent hydrolytic instability of the
silicon-nitrogen bond [7]. It has been found that the existence of
bulky substituents on the silicon atoms increases the thermal and
hydrolytic stability of cyclodisilazanes. Therefore, phenyl-
substituted cyclodisilazanes are expected to be introduced into
the backbone of linear polysiloxane chains to synthesize thermally
resistant elastomers [8,9]. An important goal in this area is the
synthesis of cyclodisilazane monomer [10e16] with a feasible
structure. While several cyclodisilazanes bearing phenyl groups
have been reported [3,17,18], few works refer to the mixed phenyl-
substituted cyclodisilazanes which exhibit unique structural char-
acteristic. The molecular structure of these cyclodisilazanes with
phenyl substituents can be described as XR2Si[NSiMePh]2SiR2X. We
have recently demonstrated that these cyclodisilazanes possess
favorable thermal stability with good prospects. Breed and Bao
[19,20] respectively reported the preparation of (ClSiMePh)2(NSi-
MePh)2, which was simply characterized by 1H NMR and IR
remained so far unknown.
In this paper, we report the improved synthesis of 1,3-
bis(hydroxysilyl)-2,4-dimethyl-2,4-diphenylcyclodisilazane (5 and
6) and the molecular structure of trans isomer (trans-5 and trans-6).
In particular, the stepwise reactions are analyzed by the inspection
of 29Si NMR spectra.
2. Results and discussion
2.1. Synthesis
1,3-Dichlorodisilazanes (1, 2) required for the formation of
cyclodisilazanes were prepared via the trans-silylation reactions
[21,22] of (Me3Si)2NH with dichlorosilane (Scheme 1). The reaction
of (Me3Si)2NH with MePhSiCl2 proceeded smoothly to give the
expected 1,3-dichlorodisilazane 1. The reaction could be acceler-
ated while large excess of MePhSiCl2 was used at high temperature.
The intermediate mixed disilazane by substitution of one trime-
thylsilyl group was also obtained in the condition of a lower
temperature or using a deficient amount of dichlorosilane. The
procession was carried out easily to bring the intermediate
compound of Me3SiNHSiRPhCl (1a, 1b) which was expected to be
valuable for the synthesis of designed 1,3-dichlorodisilazane. The
signal of the chloro-silyl group was observed with a high-field
chemical shift in the 29Si NMR spectrum (1a: 6.56, 1.56 ppm; 1b:
* Corresponding author. Tel.: þ86 010 62554494.
E-mail address: zhangzj@iccas.ac.cn (Z. Zhang).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.07.002

3246
Y. Zheng et al. / Journal of Organometallic Chemistry 696 (2011) 3245e3250
temperature for the chlorine-terminated disilazane which resulted
in a series of rearrangements [18]. As a result, 1 or 2 provided with
reactive chloro-silyl groups could further undergo self-
redistribution or react with each other. All the possible intercon-
versions accounting for the presence of several dichlorosilazanes in
the remaining crude are illustrated in Scheme 2 (inspected by 29Si
NMR). Moreover, such side reactions even continued during the
distillation of 2. Therefore, 2 was isolated possibly with little
admixture of dichlorosilane and 1.
Generally, the use of butyllithium provides an advantageous
route to a variety of cyclodisilazane monomers. The mechanism
features primary metalation at nitrogen of a 1,3-dichlorodisilazane
followed by a bimolecular condensation to a trisilylamine structure
with subsequent ring closure [19]. The 1,3-bis(chloro-silyl)-2,4-
dimethyl-2,4-diphenylcyclodisilazane 3 and 4 were synthesized
by stepwise reactions as shown in Scheme 3. We found that nearly
quantitative conversion to such cyclodisilazanes could occur at
70 ꢁC which offered a mild condition compared to the previously
reported work [19,20]. When the ring-closure reaction of 1 or 2 was
performed using an equivalent of n-BuLi in toluene, 3 was obtained
in large quantities as a mixture of cis/trans isomers while 4 was
formed as trans-cyclodisilazane. However, the mixed isomers of 3
turned out to be hydrolytically unstable, our attempt to isolate the
cis and trans-structures by crystallization failed.
For these mixed phenyl-substituted cyclodisilazanes, isomeric
structures probably appeared as a result of the transmission of
substituent effects throughout the Si4N2 skeleton which indicated
that long-range coupling could occur through silicon in the struc-
ture C6H5SiCH3 [19]. Of particular interest was the spectrum of 3,
the mixture of cis/trans isomers was clearly observed in the 29Si and
13C NMR spectra.
Scheme 1.
5.92, ꢀ8.23 ppm). However, our initial attempt to obtain 2 by
replacing another trimethysilyl group of the intermediate
compound with dichlorosilane (either route A or B) was unsuc-
cessful. Instead, a mixture of symmetrical 1,3-dichlorodisilazane
(either HN(SiMePhCl)2 or HN(SiPh2Cl)2) and unreacted 1a or 1b
was were found as the principal product of conversion. The varied
substitution product revealed that there was
a competition
between SiMe3 and SiRPhCl group for the trans-silylation reaction
of the intermediate compound Me3SiNHSiRPhCl (1a or 1b). From
the observed reactivity, we presumed that the exchange reaction of
the intermediate compound was accessible to SiRPhCl group since
nucleophilic attack of SieN bond occurred more easily when
electron-withdrawing chlorine atom was attached to silicon atom.
On the basis of these results, we focused our attention to the
exchange reaction of 1,3-dichlorodisilazane with dichlorosilane
[23]. If a large quantity of 2 was desired, this would be the method
of choice. The reaction of 1 with Ph2SiCl2 (molar ratio ¼ 1:1.1)
successfully afforded 2, where heating the reaction mixture over
160 ꢁC under distilling off MePhSiCl2 is required. The yield of 2 was
greater than 60%, as determined by 29Si NMR of the crude reaction
mixture.
The 29Si NMR spectrum of 3 showed a chloro-silyl resonance
at ꢀ2.38 ppm. As shown in Fig. 1, two stereoisomers of 3, which are
called cis and trans isomers are based on the configuration of two
phenyl groups on the Si2N2 ring. The two phenyl groups are
oriented in the same direction, the diastereomer is referred to as cis,
whereas, when the phenyl substituents are oriented in opposing
directions, the diastereomer is referred to as trans. Accordingly, the
mixture of cis/trans isomers gave rise to two sets of signals for the
endocyclic silicon atoms. The silicon resonance of cis-3 (ꢀ3.10 ppm)
in which the silicon-attached phenyl groups are on the same face of
the Si2N2 ring, shifted downfield relative to the corresponding
silicon atoms in trans-3 (ꢀ3.46 ppm) [26] with the integrated area
ratio of 4:6. The 13C NMR analysis also revealed the presence of
mixed isomers (cis/trans ¼ 40/60). For cis-3, the different substitu-
ents on the pendent silicon could influence the methyl groups on
the Si2N2 ring which are oriented in the same direction to give two
However, the asymmetrical 1,3-dichlorosilazane 2 remained
thermally unstable and could further undergo redistribution reac-
tions which result in a lower yield (33%) [24,25]. In fact side reac-
tions of SieN bond cleavage became appreciable at high
Scheme 2.

Y. Zheng et al. / Journal of Organometallic Chemistry 696 (2011) 3245e3250
3247
Scheme 3.
separate singlets (cis-3: 0.76, 1.36 ppm) in the 13C NMR spectra
possibly due to the coplanar geometry, whereas single sharp
resonance assigned to the trans isomer (trans-3: 1.05 ppm). In
contrast, the 29Si and 13C NMR spectrum of 4 showed only one
singlet resonance for endocyclic silicon atoms (ꢀ14.80 ppm) and
methyl carbon (1.40 ppm) which indicated the chemical equiva-
lency for the trans isomer.
In order to explain these observations, we have considered that
the nature of the substituents on the exocyclic silicons seems to
have great effect on the formation of stereoisomers. The steric
factors appear to influence the observed structure, particular in 3
and 4. A mixture of cis/trans isomers was obtained in 3 as compared
to 4, where only trans isomer was formed. For 3, the existence of
less bulky methyl groups on the exocyclic silicons allows for less
influence of steric hindrance on cyclodisilazane formation and
thereby can display cis/trans isomerism. On the other hand, steric
constraints around the pendent silicons with substitution of both
phenyls in 4 favor the formation of trans configuration.
Compound 3 (mixed isomers) and 4 were subsequently con-
verted into 1,3-bis(hydroxysilyl)-2,4-dimethyl-2,4-diphenylcy-
clodisilazane 5 and 6 by hydrolysis in the presence of aqueous
ammonia. The substitution of two chlorine atoms was detected by
29Si and 13C NMR spectra which also indicated only trans isomers
were obtained. The 29Si NMR spectrum for 5 and 6 showed the silyl
hydroxyl signals at ꢀ20.10 and ꢀ31.70 ppm and endocyclic-Si
signals at ꢀ5.66 and ꢀ4.37 ppm, respectively. The integration
ratio of the exocyclic-Si signal was fully consistent with the
endocyclic-Si in the spectrum. The 13C NMR spectrum of 5 exhibited
single peak for methyl carbons on the ring, which can be inter-
preted that only trans isomer was left after hydrolysis.
(842) cmꢀ1 [13,19]. The peaks at 1015 (1018) cmꢀ1 and 697 (699)
cmꢀ1 are typical for asymmetric stretching of SieNeSi and SieC
symmetric stretching, respectively. The spectrum exhibits CeH
stretching in the phenyl group at 3003, 3050 and 3069 cmꢀ1. A
strong peak at 1427 cmꢀ1 and three weak peaks at 1826, 1895 and
1960 cmꢀ1 are associated with the phenyl-Si vibration. It shows
a similar spectrum to its corresponding cyclosilazane with extra
absorption peaks at 503 (510) and 532 (541) cmꢀ1 for the
stretching of SieCl and 3585 cmꢀ1 for SieOH.
As reported, bulky groups such as phenyl greatly decreased the
reactivity of hydrolysis under acidic or basic conditions and left the
Si2N2 ring intact [7]. However, the structure of Si2N2 with mixed
phenyl groups especially for cis-3 apparently had little effect on the
hydrolysis [27]. Further reaction involving the cleavage of endo-
cyclic SieN bonds occurred to produce the siloxane derivatives
(MePhSiO)3,4 which were detected by 29Si NMR spectra and this
accounted for the low yield (47%) of compound 5. Trans-5 was
formed predominantly during the hydrolysis reaction since trans-3
is supposed to have greater hydrolytic stability, whereas cis-3 was
hydrolytically unstable and underwent complete hydrolysis with
The FT-IR spectra of the cyclodisilazane monomers (3, 4, 5 and
6) are shown in Fig. 2. The cyclic Si4N2 skeleton is confirmed by
the existence of absorption peaks at 1116 (1118) cmꢀ1 and 829
Fig. 1. Isomeric structures of cis-3 and trans-3.
Fig. 2. FT-IR spectra of cyclodisilazane monomers (3, 4, 5 and 6).

3248
Y. Zheng et al. / Journal of Organometallic Chemistry 696 (2011) 3245e3250
the decomposition of the Si2N2 ring. Consequently, we have
considered that the predominant formation of trans-5 is apparently
attributed to the influence of steric hindrance of oriented phenyls
in trans-3 which could largely shield the Si2N2 ring from hydrolytic
cleavage.
2.2. Molecular structures
The molecular structures of trans-5 and trans-6 are illustrated in
Figs. 3 and 4. Selected bond and angle parameters are listed in the
caption of the figure. The structures of trans-5 and trans-6 con-
sisting a mixed substituted Si2N2 ring are almost similar. The
cyclodisilazane forms a planar Si2N2 heterocycle with N-SieN and
SieNeSi angles of 89.18ꢁ, 90.82ꢁ in trans-5 and 89.23ꢁ, 91.77ꢁ in
trans-6, respectively. Such values are in good agreement with the
symmetrical substituted Si2N2 ring determined previously [28e32].
The geometry around the nitrogen atom is coplanar to within
ꢁ
ꢀ
0.04 A and the sum of the valency angles is approximately 360 . The
planarity of the nitrogen atom attached to the ring indicates
Fig. 4. X-ray crystal structure of trans-6. Hydrogen atoms are omitted for clarity.
ꢁ
ꢀ
delocalization of its unshared electron pair as a result of dpepp
Selected bond distances [A] and angles [ ]: Si(1)eO(1) 1.627(2), Si(1)eN(1) 1.710(3),
Si(2)eN(1) 1.754(3), Si(4)eN(1) 1.730(3), Si(2)eC(13) 1.855(4), Si(2)eC(14) 1.864(4),
Si(2)eN(1)eSi(4) 91.77(15), N(1)eSi(2)eN(1A) 88.22(15), Si(1)eN(1)eSi(4) 132.62(18),
Si(1)eN(1)eSi(2) 132.98(18), N(1)eSi(2)eC(13) 113.30(16), N(1)eSi(2)eC(14)
113.84(16), C(13)eSi(2)eC(14) 107.27(17).
interaction with Si(1), Si(2) and Si(2A)/Si(4). The Si(2) adopts
a distorted tetrahedral geometry that ranges from a rather acute
intraannular N-SieN angle (trans-5: 88.81ꢁ, trans-6: 89.23ꢁ) to
a
comparatively obtuse extraannular CeSieC angle (trans-5:
110.31ꢁ, trans-6: 109.97ꢁ). The orientation of the phenyl groups on
the ring is represented by the torsion angle of CeSi(2)eSi(2A)/
Si(4)eC (trans-5: 171.5ꢁ, trans-6: 178.5ꢁ). As expected, the plane of
the phenyl groups forms trans-structure among the planar Si2N2
reaction of the intermediate compound Me3SiNHSiRPhCl is acces-
sible to SiRPhCl group. Owing to the mixed phenyl substituents
attached to the Si4N2 skeleton, cyclodisilazane 3 was confirmed as
a mixture of cis/trans isomers by 29Si, 13C NMR analysis. Trans-5 was
obtained by hydrolysis of the isomeric mixture of 3. The molecular
structures of trans-5 and trans-6 show that the geometrical
parameters are nearly identical, which exhibit similar characteristic
for the cyclodisilazane molecules of this type. Further work will
concentrate on obtaining the cis-5 in order to have a further
understanding of its hydrolytic stability.
ꢀ
ꢀ
ring. The Si(1)eN(1) bond length (trans-5: 1.712 A, trans-6: 1.699 A)
is significantly shorter than the Si(2)eN(1) or Si(4)eN(1) bond
length (trans-5: 1.742, 1.753 A; trans-6: 1.730, 1.754 A). The endo-
ꢀ
ꢀ
cyclic silicon atoms approach strikingly to each other that the
ꢀ
ꢀ
transannular Si/Si distance (trans-5: 2.48 A, trans-6: 2.50 A) goes
ꢀ
near to van der Waals radii of the SieSi bond (2.32 A in Si2Cl6).
3. Conclusion
We have synthesized 1,3-dichlorodisilazane 1 and 2 via a trans-
silylation reaction. The inspection indicates that the exchange
4. Experimental
4.1. General
All manipulations were carried out under exclusion of moisture
in an inert nitrogen atmosphere and solvents were dried
adequately and distilled prior to use. The NMR spectra were
recorded on Bruker AVANCE 400 (1H, 13C 400 MHz) and DMX300
(
29Si 300 MHz) spectrometers. All chemical shifts are reported as
d
values (ppm) relative to residual chloroform (dH 7.26), the central
peak of CDCl3 dC 77.0) and tetramethylsilane (dSi 0.0). Elemental
(
analyses were performed using a FLASH EA 1112 Microanalytical
analyzer. Fourier transfer infrared spectra (FT-IR) were recorded
with a Bruker TENSOR-27 IR spectrometer. GC-MS (EI) was
measured by SHIMADZU (GC-MS-QP2010). Melting point was
carried out in a WRS-1A digital melting point apparatus.
4.2. Synthesis of 1,3-dichloro-1,3-dimethyl-1,3-diphenyldisilazane (1)
A mixture of 80.5 g (Me3Si)2NH, (0.5 mol) and 191.1 g (1.0 mol)
MePhSiCl2 was stirred at 120 ꢁC under distillation of Me3SiCl for
over 12 h. After Me3SiCl was totally distilled out, the mixture was
cooled to room temperature. The crude product was distilled under
vacuum (0.1 Torr) to give 1 (102.4 g 63%) as a colorless viscous
Fig. 3. X-ray crystal structure of trans-5ꢁ. Hydrogen atoms are omitted for clarity.
ꢀ
Selected bond distances [A] and angles [ ]: Si(1)eO(1) 1.634(3),Si(1)eN(1) 1.712(2),
Si(2)eN(1) 1.742(2), Si(2A)eN(1) 1.753(3), Si(2)eC(8) 1.857(3), Si(2)eC(9) 1.870(3),
Si(1)eN(1)eSi(2) 133.28(15), Si(1)eN(1)eSi(2A) 135.90(15), Si(2)eN(1)eSi(2A)
90.82(12), N(1)eSi(2)eN(1A) 89.18(12), N(1)eSi(2)eC(8) 114.65(14), N(1)eSi(2)eC(9)
113.39(12), C(8)eSi(2)eC(9) 110.31(14).
liquid. Bp. 152 ꢁC (0.1 Torr): 1H NMR:
7.11e7.97 [m, 10H, Si(C6H5)], 1.95 [s, 1H, HNSi2]. 13C NMR:
d
0.58, 0.65 [s, 6H, Si(CH3)],
3.13 [s,
d

Y. Zheng et al. / Journal of Organometallic Chemistry 696 (2011) 3245e3250
3249
2C, Si(CH3)], 128.16e134.68 [m, 12C, Si(C6H5)]. 29Si NMR:
2Si, ClSi(CH3)(C6H5)].
d
2.66 [s,
calcd for C28H34Si4N2O2 542.17). Anal. Calcd. for C28H34Si4N2O2 (%):
C, 61.94; H, 6.31; N, 5.16. Found (%): C, 61.99; H, 6.51; N, 4.94.
In the same manner described above, 6 was prepared from 4
(105.6 g, 0.15 mol) and isolated as a colorless crystal (87.9 g, 88%).
4.3. Synthesis of 1,3-dichloro-1-methyl-1,3,3-triphenyldisilazane (2)
Mp. 144.8e146.9 ꢁC. 1H NMR:
d 2.17, [s, 2H, SiOH], 0.64 [s, 6H,
N2Si(CH3)], 7.2e7.8 [m, 30H, Si(C6H5)]. 29Si NMR:
d
ꢀ31.70 [s, 2Si,
After a mixture of 50.6 g (0.2 mol) Ph2SiCl2 and 65.2 g (0.2 mol)
1 was maintained at a temperature of 160 ꢁC for 8 h, an attempt to
separate 2 was conducted. When the crude products were frac-
tional distilled, 2 would disproportionate to give a series of frac-
tions containing 1, 1,3-dichlorotetraphenyldisilazane, chlorosilane
and trimeric polysilazane. The distillates of 1, 2 and chlorosilane
were collected and after a second fractional distillation, 26.6 g
(33%) of 2 was ultimately obtained with the purity of 88%, Bp.
Si(C6H5)2OH], ꢀ4.37 [s, 2Si, N2Si(CH3)(C6H5)]. 13C NMR:
d 1.30 [s,
2C, N2Si(CH3)], 127.32e138.73 [m, 36C, Si(C6H5)]. IR (KBr): v
SieOH 3584 cmꢀ1; v Si4N2 843, 1014, 1118 cmꢀ1. GC-MS m/z
666.78 (Mþ, calcd for C38H38Si4N2O2 666.20). Anal. Calcd. for
C38H38Si4N2O2 (%): C, 68.42; H, 5.74; N, 4.20. Found (%): C, 68.84;
H, 5.89; N, 4.09.
186 ꢁC (0.1 Torr): 1H NMR:
d
0.62 [s, 3H, Si(CH3)], 7.19e7.86 [m, 15H,
3.52 [s, 1C, Si(CH3)],
3.20 [s, 1Si,
4.6. Crystal structure determination of trans-5 and trans-6
Si(C6H5)], 2.26 [s, 1H, HNSi2]. 13C NMR:
d
128.24e134.57 [m, 18C, Si(C6H5)]. 29Si NMR:
ClSi(CH3)(C6H5)], ꢀ7.93 [s, 1Si, ClSi(C6H5)2].
d
Single crystal of trans-5 and trans-6 suitable for X-ray crystal-
lographic analyses were grown by slow evaporation of their
respective solution in diethyl ether/n-hexane at room temperature.
The diffraction experiments were carried out at 276 K on a Rigaku
4.4. Synthesis of 1,3-bis(chloromethylphenylsilyl)-2,4-dimethyl-2,4-
diphenylcyclodisilazane (3) and 1,3-bis(chlorodiphenylsilyl)-2,4-
dimethyl-2,4-diphenylcyclodisilazane (4)
RAXIS-RAPID diffractometer with graphite-monochromated Mo K
a
ꢀ
radiation
(l
¼ 0.71073 A). Data were processed using PROC-
ESSAUTO program package, and absorption corrections were
applied by the empirical method [33].
After 160 ml (0.4 mol) of 2.5 M n-Butyl lithium in hexane was
added dropwise to a stirred solution of 130.4 g (0.4 mol) 1 in 600 ml
toluene at 0 ꢁC, the reaction mixture was allowed to rise steadily to
refluxing temperature and stayed for 6 h. The precipitate of LiCl was
filtered off quickly and the solvent was evaporated from the filtrate
to give colorless crystal of 3 (85.5 g, 74%). Mp. 118.2e123.9 ꢁC. 1H
The structures were solved by direct method [34] using SIR92
and refined on F2 (with all independent reflections) by the full-
matrix least-squares technique using SHELXL97 program. All non-
hydrogen atoms were refined anisotropically, and hydrogen atoms
were introduced at the positions calculated theoretically and
treated with riding models. Details on crystal and intensity data
collection are given in Table 1.
NMR: d 0.32, 0.34 and 0.36 [s, 6H, N2Si(CH3)], 0.52, 0.63, 0.75 [s, 6H,
Si(CH3)Cl], 7.23e7.89 [m, 20H, Si(C6H5)]. 29Si NMR:
d
ꢀ2.38 [s, 2Si,
Si(CH3)(C6H5)Cl], ꢀ2.98 and ꢀ3.59 [s, 2Si, N2Si(CH3)(C6H5)]. 13C
NMR:
d 0.76, 1.05 and 1.36 [s, 2C, N2Si(CH3)], 2.92 and 3.12 [s, 2C,
Table 1
Si(CH3)Cl], 126.92e136.76 [m, 24C, Si(C6H5)]. IR (KBr): v SieCl 503,
X-ray diffraction data and structure refinement details for trans-5 and trans-6.
532 cmꢀ1 Si4N2 829, 1018, 1115 cmꢀ1
;
v
.
Anal. Calcd. for
Compound
trans-5
28H34N2O2Si4
542.93
Triclinic
P-1
9.512(3)
9.789(3)
16.040(5)
85.19(7)
83.57(7)
87.68(6)
1478.2(8)
2
trans-6
C28H32Si4N2Cl2 (%): C, 58.00; H, 5.56; N, 4.83; Cl, 12.23. Found (%): C,
57.10; H, 5.61; N, 4.86; Cl, 12.45.
In the same manner described above, 4 was prepared from 2
(155.2 g, 0.4 mol) and 2.5 M n-Butyl lithium in hexane (160 ml,
0.4 mol) and isolated as a colorless crystal (91.2 g, 65%). Mp.
Formula
C
C38H38N2O2Si4
667.06
Triclinic
P-1
10.389(2)
16.992(3)
21.085(4)
70.27(3)
84.98(3)
87.40(3)
3489.7(11)
4
fw (g molꢀ1
)
Crystal system
Space group
ꢀ
a (A)
179.6e182.4 ꢁC. 1H NMR:
d
0.53 [s, 6H, N2Si(CH3)], 6.81e7.63 [m,
ꢀ14.80 [s, 2Si, Si(C6H5)2Cl], ꢀ1.90 [s,
ꢀ
b (A)
30H, Si(C6H5)]. 29Si NMR:
d
ꢀ
c (A)
(ꢁ)
(ꢁ)
(ꢁ)
N2Si(CH3)(C6H5)]. 13C NMR:
d 1.40 [s, 2C, N2Si(CH3)], 127.62e137.34
a
b
g
[m, 36C, Si(C6H5)]. IR (KBr): v SieCl 510, 541 cmꢀ1; v Si4N2 828,
1016, 1116 cmꢀ1. Anal. Calcd. for C38H36Si4N2Cl2 (%): C, 64.83; H,
5.25; N, 3.98; Cl, 10.07. Found (%): C, 64.54; H, 5.20; N, 4.05; Cl,
10.39.
3
ꢀ
V (A )
Z
r
(g cmꢀ3
)
1.220
1.270
Crystal size (mm)
0.31ꢂ0.26ꢂ0.20
0.32ꢂ0.28ꢂ0.05
Abs coeff (mmꢀ1
T (ꢁC)
)
0.228
0.207
23
23
4.5. Synthesis of 1,3-bis(hydroxymethylphenylsilyl)-2,4-dimethyl-
2,4-diphenylcyclodisilazane (5) and 1,3-bis(hydroxydiphenylsilyl)-
2,4-dimethyl-2,4-diphenylcyclodisilazane (6)
Radiation
Mo-Ka
ꢀ
(
l¼ 0.71073 A)
graphite-
monochromated
1.28～25.34
ꢀ11 ꢃ h ꢃ 11
ꢀ11 ꢃ k ꢃ 11
ꢀ19 ꢃ l ꢃ 19
14,436
A solution of 124 g (0.15 mol) 3 in 200 ml diethyl ether was
added to 120 ml of a mixture (H2O: aqueous ammonia ¼ 6:1 vol.%)
in 200 ml diethyl ether at 0 ꢁC. After vigorous stirring for 30 min,
the mixture was shaken with water to remove the ammonia chlo-
ride and the solvent was distilled off under reduced pressure. The
residue was recrystallized from the mixed solvent of diethyl ether
and hexane to give 5 (38.21 g 47.0%) as white crystals. Mp.
2
q
range(ꢁ)
Index ranges
1.03～25.38
ꢀ12 ꢃ h ꢃ 11
ꢀ19 ꢃ k ꢃ 20
ꢀ25 ꢃ l ꢃ 25
33,903
12758 (Rint ¼ 8.43%)
Semi-empirical from
equivalents
1.0000/0.7623
12758/0/829
0.0807
No. of reflns collected
No. of indep. reflns.
Absorp. corr.
5402 (Rint ¼ 3.50%)
Numerical
Transmission: tmin/tmax
0.9558/0.9326
5402/0/329
0.0594
0.1677
1.222
106.3e108.2 ꢁC. 1H NMR:
N2Si(CH3)], 0.13 [s, 6H, Si(CH3)OH], 7.09e7.58 [m, 20H, Si(C6H5)].
29Si NMR:
ꢀ20.10 [s, 2Si, Si(CH3)(C6H5)OH], ꢀ5.66 [s, 2Si,
N2Si(CH3)(C6H5)]. 13C NMR:
1.26 [s, 2C, N2Si(CH3)], 0.12 [s, 2C,
d 1.72, [s, 2H, SiOH], 0.60 [s, 6H,
Data/restraints/parameters
R(F2 > 2
s
(F2))
wR(F2)
0.1846
1.081
0.602/ꢀ0.447
d
Goodness-of-fit
Largest diff peak/hole
d
0.506/ꢀ0.403
Si(CH3)OH], 127.32e138.84 [m, 24C, Si(C6H5)]. IR (KBr): v SieOH
ꢀꢀ3
(e A
)
3585 cmꢀ1; v Si4N2 842, 1015, 1118 cmꢀ1. GC-MS m/z 542.96 (Mþ,

3250
Y. Zheng et al. / Journal of Organometallic Chemistry 696 (2011) 3245e3250
[12] L.W. Breed, W.L. Budde, R.L. Elliott, J. Organomet. Chem. 6 (1966) 676e679.
Acknowledgement
[13] L.W. Breed, R.L. Elliott, J.C. Wiley, J. Organomet. Chem. 24 (1970) 315e325.
[14] G.H. Wiseman, D.R. Wheeler, D. Seyferth, Organometallics 5 (1986) 146e152.
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[17] L.W. Breed, R.L. Elliott, J.C. Wiley, J. Organomet. Chem. 31 (1971) 179e185.
[18] W. Fink, Helv. Chim. Acta 51 (1968) 1743e1750.
[19] L.W. Breed, J.C. Wiley, Inorg. Chem. 11 (1972) 1634e1638.
[20] X.J. Bao, M.J. Edirisinghe, J. Mater. Chem. 10 (2000) 395e401.
[21] E. Bacqué, J.-P. Pillot, M. Birot, et al., J. Organomet. Chem. 481 (1994) 167e172.
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We are grateful to the National Natural Science Foundation of
China (No. 50803070) for financial support.
Appendix A. Supplementary material
Crystallographic data for the structural analysis have been
deposited with the Cambridge Crystallographic Data Centre, CCDC-
804075 for trans-6 and CCDC-804076 for trans-5. These data can be
obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif.
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