New cyclic stannyloligosilanes

Article abstract of DOI:10.1016/S0022-328X(97)00755-9

The synthesis of new cyclic stannyloligosilanes [R₂Sn(SiMe₂)_n] (2a, n=5, R=Ph; 2b, n=5, R=Me; 3a, n=6, R=Ph; 3b, n=6, R=Me) is reported. The compounds are fully characterised by mass spectrometry and NMR spectroscopy and i

Full text of DOI:10.1016/S0022-328X(97)00755-9

Journal of Organometallic Chemistry 556 (1998) 165–167
New cyclic stannyloligosilanes
C. Kayser, R. Klassen, M. Schu¨rmann, F. Uhlig *
Anorganische Chemie II, Uni6ersita¨t Dortmund, Otto-Hahn-Straße 6, D-44221, Dortmund, Germany
Received 2 October 1997; received in revised form 17 November 1997
Abstract
The synthesis of new cyclic stannyloligosilanes [R2Sn(SiMe2)n] (2a, n=5, R=Ph; 2b, n=5, R=Me; 3a, n=6, R=Ph; 3b,
n=6, R=Me) is reported. The compounds are fully characterised by mass spectrometry and NMR spectroscopy and in the case
of 2a also by X-ray analysis. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Cyclic stannylsilanes; 29Si-, 119Sn-NMR spectroscopy; Crystal structure
b are colourless, crystalline compounds. They are stable
on air for hours and soluble in common organic sol-
vents such as acetone, n-alkanes and ethers. The 29Si-
and 119Sn-NMR data are given in Table 1. The molecu-
lar structure of 2a is shown in Fig. 1.
1. Introduction
Cyclic silanes are well known as reagents in
organometallic chemistry and material science [1].
However, to the best of our knowledge, only one cyclic
organostannylsilane, i.e. decaphenylcyclostannatetrasi-
lane 1, is known [2].
Crystal data and structure solution of 2a:
C22H40Si5Sn, M=563.68, orthorhombic, Pbca, a=
˚
14.853(1), b=13.686(1), c=30.555(1) A, V=6211.2(6)
In a previous paper, we reported an Si–Sn-coupling
reaction from triorganochlorostannanes with mono-
fluorosilanes and magnesium [3]. Here we describe first
results on reactions of h,ꢀ-difluorosilanes with diorgan-
odichlorostannanes and magnesium to form the cyclic
monostannylsilanes 2a, 2b, 3a, 3b in moderate yields
(Scheme 1).
The 1,2,3,4,5-pentasila-6-stanna-cyclohexanes 2a, b
and the 1,2,3,4,5,6-hexasila-7-stanna-cycloheptanes 3a,
* Corresponding author. Fax: +49 231 7553797.
Scheme 1. Synthesis of cyclic stannyloligosilanes 2 and 3.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(97)00755-9

166
C. Kayser et al. / Journal of Organometallic Chemistry 556 (1998) 165–167
Table 1
x
119Sn- and 29Si-NMR data for 2a, b and 3a, b (l [ppm] and JSi-119/117Sn [Hz])
119Si-NMR
29Sn-NMR
Sib
Sia
1JSi-119/117Sn
2JSi-119/117Sn
Sic
3JSi-119/117Sn
2aa
2b
−223.05
−242.6
−224.1
−243.6
−34.9
−38.8
−34.4
−38.5
368/350
387/370
370/354
390/373
−38.4
−39.2
−38.7
−39.1
99/94
93/88
94/90
92/88
−41.5
−42.1
−41.4
−41.5
24
—
30
—
b
3a
3bc
b
a 1J(Sia–Sib) 61.3 Hz; 2J(Sia–Sic) 9.8 Hz; 1J(Sib–Sic) 62.5 Hz.
b Not found.
c 1J(Sia–Sib) 60.3 Hz; 2J(Sia–Sic) 9.2 Hz; 1J(Sib–Sic) 61.6 Hz; 2J(Sib–Sic) 8.9 H.
3
A , Z=8, Dcalc. =1.206 g cm−3; (Mo–Kh)=0.71069
crude product is purified by recrystallisation or Kugel-
rohr distillation.
˚
˚
A, F(000)=2336, T=291(1) K. The data were col-
lected to a maximum u of 20.84° with 360 frames via
ꢀ-rotation (D/ꢀ=1°) two times 10 s per frame on a
NONIUS KappaCCD diffractometer. The structure
was solved by direct methods SIR92 [6] and refined by
full-matrix least squares calculations using all measured
F2 data and SHELXL93 [7]. All non-H atoms were
refined anisotropically. The H atoms were placed in
geometrically calculated positions and refined with
2.1.1. 6,6-diphenyl-decamethyl-1,2,3,4,5-pentasila-6-
stanna-cyclohexane 2a
Starting materials: 2.09 g (6 mmol) F–(SiMe2)5–F,
2.17 g (6 mmol) Ph2SnCl2. For 2a the residue is ex-
tracted with hexane. The crude product is purified by
recrystallisation with acetone to afford the product in a
yield of 1.35 g (40%). m.p. 180–182°C.
MS(EI): m/e 564 [M+], 487 [PhSn(SiMe2)5+], 429
[PhSn(SiMe2)4+], 414 [PhSn(SiMe2)3SiMe+], 352 [Sn
(SiMe2)4+], 294 [Sn(SiMe2)3+]. 1H-NMR [ppm]: 7.15 (m,
˚
common isotropic temperature factors (C–Haryl 0.93 A,
3
3
˚
˚
˚
Uiso 0.135(7) A ; C–Halkyl 0.96 A, Uiso 0.154(4) A ).
R1=0.0245 for 1964 [I\2 (I)] and wR2=0.0564 for
3206 independent reflections. The maximum and mini-
mum residual electron densities were 0.334 and −0.167
3
10H, 2×Ph); 0.31 (s, 12H, SiaMe); JSn-H=33.2/31.9
Hz; 0.07 (s, 18H, SibMe, SicMe). Found: C 46.85, H
7.14. C22H40Si5Sn. Calc.: C 47.3, H 7.8.
e A−3. Full details have been deposited with the Cam-
˚
bridge Crystallographic Data Centre and are also avail-
able in CIF format from the author.
Preliminary investigations show that 1,3-difluoro-
hexamethyltrisilane and 1,4-difluoro-octamethyltetrasi-
lane, respectively, react with R2SnCl2 under formation
of cyclic stannylsilanes with more than one tin atom.
2. Experimental
All syntheses were carried out using Schlenk-tech-
niques to exclude oxygen and moisture. Solvents were
dried by known methods. h,ꢀ-difluorooligosilanes were
obtained from dichloro- or dibromooligosilanes [4] and
[Bu4N][Ph3SnF2] [3,5].
2.1. General procedure
In
a typical reaction one equivalent h,ꢀ-difl-
uorooligosilane, one equivalent R2SnCl2 and three
equivalents Mg (50% excess) are stirred in THF at
room temperature. After a few hours the mixture turns
to green–black indicating the start of the reaction.
Stirring is continued for 5–8 days. After removing the
solvent in vacuo, the residue is extracted with n-hexane
or CH2Cl2. The solvents are removed in vacuo. The
Fig. 1. General view of a molecule of (1) showing 30% probability
displacement ellipsoids and atom numbering (SHELXTL-PLUS) [8].
Important parameters: Sn–Si(1) 2.5670(13), Sn–Si(5) 2.5701(13), Sn–
C(21) 2.136(5), Sn–C(11) 2.156(4), Si(1)–Sn–Si(5) 108.45(13), Si(5)–
Sn–C(21) 112.5(2), Si(1)–Sn–C(21) 110.9(2).

C. Kayser et al. / Journal of Organometallic Chemistry 556 (1998) 165–167
167
2.1.2. Dodecamethyl-1,2,3,4,5-pentasila-6-stanna-
cyclohexane 2b
[MeSn(SiMe2)5+], 367 [MeSn(SiMe2)4+], 348 [(SiMe2)6+],
335 [SnSi4Me7+], 290 [(SiMe2)5+], 232 [(SiMe2)4+], 131
1
Starting materials: 1.96 g (5.95 mmol) F–(SiMe2)5–
F, 1.13 g (5.95 mmol) Me2SnCl2. For 2b the residue is
extracted with hexane. The crude product is purified by
recrystallisation with ether to afford the product in a
yield of 1.17 g (45%). m.p. 120–123°C.
[Me3Si2Me2+], 73 [Me3Si+]. H-NMR [ppm]: 0.23 (s,
3
12H, SiaMe); JSn-H=35/33.3 Hz; 0.12 (s, 6H, SnMe);
−0.07 (s, 24H, SibMe, SicMe). Found: C 33.76, H 8.50.
C14H42Si6Sn. Calc.: C 33.15, H 8.2.
MS(EI): m/e 439 [M+], 424 [MeSn(SiMe2)5+], 367
[MeSn(SiMe2)4+], 352 [Sn(SiMe2)4+], 294 [Sn(SiMe2)3+].
Acknowledgements
3
1H-NMR [ppm]: 0.28 (s, 12H, SiaMe); JSn-H=34/32.4
Hz; 0.15 (s, 6H, SnMe); 0.06 (s, 18H, SibMe, SicMe).
Found: C 32.29, H 8.26. C12H36Si5Sn. Calc.: C 33.1, H
8.42.
The authors thank the Deutsche Forschungsgemein-
schaft for financial support (DFG-project Uh74-3) and
the ASV-innovative Chemie GmbH (Bitterfeld) for the
generous gift of silanes. We are also grateful to Profes-
sor Dr. K. Jurkschat (Universita¨t Dortmund/Germany)
for supporting this investigation.
2.1.3. 7,7-diphenyl-dodecamethyl-1,2,3,4,5,6-hexasila-
7-stanna-cycloheptane 3a
Starting materials: 4.7 g (12.1 mmol) F–(SiMe2)6–F,
4.16 g (12.1 mmol) Ph2SnCl2.
For 3a the residue is extracted with hexane. The
crude product is purified by recrystalisation in n-hex-
ane. Yield 2.41 g (32%). m.p. 131–133°C.
References
[1] (a) E. Hengge, R. Janoschek, Chem. Rev. 95 (1995) 1443. (b) R.
West, in S. Patai, Z. Rappaport (Eds.), The Chemistry of
Organic Silicon Compounds, Wiley Interscience, NY, Ch. 19,
1989. (c) P. Kochs, in: H.R. Kricheldorf (Ed.), Silicon in poly-
mer synthesis, Springer, Berlin, Heidelberg, Ch. 4, 1996.
[2] E. Hengge, U. Brychy, M. Chem. 95 (1966) 1309.
[3] R. Hummeltenberg, K. Jurkschat, F. Uhlig, Phosphorus, Sulfur
and Silicon (1997) in press.
MS(EI): m/z 622 [M+], 564 [Ph2Sn(SiMe2)5+], 549
[Ph2Sn(Si5Me9)+], 491 [Ph2SnSi4Me7+], 428 [PhSn(-
SiMe2)4+], 352 [SnSi4Me8+], 348 [(SiMe2)6+], 309
1
[SnSi3Me7], 73 [SiMe3+]. H-NMR [ppm]: 7.29 (m, 10H,
3
2xPh); 0.36 (s, 12H, SiaMe); JSn-H=32.5/30.9 Hz; 0.08
(s, 12H, SibMe); −0.13 (s, 12H, SicMe). Found: C
46.34, H 7.45. C24H46Si6Sn. Calc.: C 45.6, H 7.7.
[4] H. Gilman, R.L. Harell, J. Organomet. Chem. 14 (1966) 317.
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M.C. Burla, G. Polidori, M. Camalli, SIR92—a program for
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Appl. Crystallogr. 27 (1994) 435.
2.1.4. Tetradecamethyl-1,2,3,4,5,6-hexasila-7-stanna-
cycloheptane 3b
Following the general procedure 3.32 g (8.57 mmol)
F–(SiMe2)6–F, 1.88 g (8.57 mmol) Me2SnCl2 and 0.62
g (25.7 mmol) Mg (50% excess) are stirred in 150 ml
THF at room temperature for 7 days. The residue is
purified by Kugelrohr distillation. We received 0.64 g
(15% yield) of a colourless solid 3b with m.p. 92–98°C.
MS(EI): m/z 498 [M+], 483 [MeSn(SiMe2)6+], 425
[7] G.M. Sheldrick, SHELXL93, Program for Crystal Structure Refin-
ement, University of Go¨ttingen, Germany, 1993.
[8] G.M. Sheldrick, SHELXTL-PLUS. Release 3.4 for Nicolet R3m/V
crystallographic system. An Integrated System for Solving,
Refining and Displaying Crystal Structures from Diffraction
Data. Nicolet Instrument Corporation, Madison, Wisconsin,
USA, 1987.
.