J. Am. Chem. Soc. 2001, 123, 8117-8118
8117
Communications to the Editor
Amine-Promoted Disproportionation and
Redistribution of Trichlorosilane: Formation of
Tetradecachlorocyclohexasilane Dianion1
Seok-Bong Choi, Beon-Kyu Kim, Philip Boudjouk,* and
Dean G. Grier
Center for Main Group Chemistry
Department of Chemistry
North Dakota State UniVersity
Fargo, North Dakota 58105
ReceiVed August 1, 2000
Amine-promoted redistributions and disproportionations of
2
chlorosilanes have been known for several decades. Typically,
the product mixtures from such reactions are complex, defying
unambiguous characterization. Recently, we demonstrated that
aliphatic diamines and triamines, when reacted with trichlorosi-
3
4
lane, produced neutral and cationic hexacoordinated complexes
of silicon in high yields and with narrow product distributions.
Here we report an unexpected and unique result: the amine-
promoted oligomerization of trichlorosilane to form the novel
2-
inverse sandwich dianion, Si
to form highly functionalized polysilanes is unprecedented.
We recently reported that the reaction of HSiCl with pedeta
in CH Cl immediately followed by the addition of hexane gave
pedeta‚H
that, if instead of adding hexane, we refluxed the solution of
HSiCl and pedeta in CH Cl at 40-45 °C for 48 h we produce
the novel complex [pedeta‚H
6
Cl14 . Efficient catenation of silanes
3
2
2
Figure 1. ORTEP diagram of 1 showing atom-labeling scheme. Some
of hydrogens are omitted for clarity. Selected bond distances (Å) and
angles (deg): Si(1)-Cl(1B), 2.070(3); Si(1)-Cl(1A), 2.087(3); Si(1)-
Si(2), 2.314(2); Si(1)-Si(6), 2.318(3); Si(2)-Cl(2B), 2.073(2); Si(2)-
Cl(2A), 2.083(2); Si(2)-Si(3), 2.323(2); Si(7)-N(5), 2.009(5); Si(7)-
N(6), 2.082(6); Si(7)-N(4), 2.092(6); Si(7)-Cl(7), 2.216(2); Cl(1B)-
Si(1)-Cl(1A), 101.72(12); Cl(1B)-Si(1)-Si(2), 108.73(10); Cl(1A)-
Si(1)-Si(2), 107.07(11); Cl(1B)-Si(1)-Si(6), 109.07(12); Cl(1A)-
Si(1)-Si(6), 109.27(12); Si(2)-Si(1)-Si(6), 119.51(10); N(5)-Si(7)-
N(6), 85.3(2); N(5)-Si(7)-N(4), 85.3(2); N(6)-Si(7)-N(4), 169.7(2);
N(5)-Si(7)-Cl(7), 178.1(2); N(6)-Si(7)-Cl(7), 93.03(16); N(4)-Si-
+
-
4
[
2
SiCl] Cl in high yield within 5 min. Here we report
3
2
2
+
2 6
SiCl ] [Si
Cl14 ] (1) (eq 1).5
2-
2
(
7)-Cl(7), 96.26(17).
positions. All of the Si-N bond distances are in the range of
Analysis of the X-ray data for 1 shows two intermolecularly
hexacoordinated cations in which the silicon atoms are at the
center of slightly distorted octahedra and a dianion comprised of
a planar cyclohexasilane ring bonded to 14 chlorine atoms forming
an “inverse sandwich structure”. To the best of our knowledge,
this structural type is unique in group 14 chemistry (Figure 1).
The chlorine atom in each cation is coplanar with the three
nitrogen atoms of pedeta and the hydrogens occupy trans
typical ionic hexacoordinate silicon compounds (The average
4
distance for Si-N in 1 is 2.069 Å). The chlorine atoms are of
(
5) Trichlorosilane (34 g, 250 mmol) was added to a clear, colorless solution
of pedeta (24 g, 100 mmol) in dry CH Cl (150 mL). A slight warming of the
reaction vessel contents occurred upon addition. After stirring for 48 h at
5-40 °C, white crystals precipitated. Filtration followed by washing with
CH Cl
(50 mL × 3) gave 9 g of 1 as a white crystalline powder. Anal. Calcd
for [(H SiCl‚pedeta) Si Cl14] (1): C, 26.22; H, 5.50; N, 6.55. Found: C, 26.25;
H, 5.42; N, 6.45. X-ray structure determination of 1: X-ray quality crystals
Si (1) were grown from a concentrated CH Cl solution at
2
2
3
2
2
2
2
6
(1) Some preliminary results have been presented: (a) Kim, B.-K. Ph.D.
of C28
70
H C
l16
N
6
8
2
2
Thesis, North Dakota State University, Fargo, North Dakota, 1998. (b)
Boudjouk, P.; Choi, S.-B.; Kim, B.-K. Presented at the Organosilicon
Symposium, Gunma, Japan, November 4-5, 1999. (c) Boudjouk, P.; Choi,
S.-B.; Kim, B.-K. Proceedings of the 32nd Great Lakes Regional Meeting of
the American Chemical Society, Fargo, North Dakota, June 4-6, 2000;
Abstract 67. (d) Boudjouk, P.; Choi, S.-B.; Kim, B.-K. Proceedings of the
room temperature. A single crystal of 1 was mounted in a thin-walled glass
capillary tube and sealed under argon. The space group is Pbca, orthorhombic,
with unit-cell dimensions a ) 19.7106(18) Å, b ) 22.1508(19) Å, c ) 27.130-
3
3
(2) Å, V ) 11845.0 (18) Å , Z ) 8, fw ) 1282.82, dcalc ) 1.439 Mg/m , F
-1
(000) ) 5312 and abs. coeff. ) 0.941 mm . Intensity data were collected at
295(2) K on a Siemens CCD SMART diffractometer with Mo KR radiation
and a graphite monochromator. A total 57160 unique reflections were
measured, and 10437 [R(int) ) 0.0570] having I > 2σ(I) were independent.
An absorption correction was applied using spherical harmonics with the
program SADABS, a component of Bruker’s SAINT package used for
reduction of area detector data. The structure was solved by direct methods
3
3rd Organosilicon Symposium, Saginaw, Michigan, April 6-8, 2000; Abstract
No. A-1.
(
2) (a) Fleischer, H.; Hensen, K.; Stumpt, T. Chem. Ber. 1996, 129, 765.
(
b) Benkeser, R.; Li, G. S.; Mozdezen, E. J. Organomet. Chem. 1971, 178,
2
1. (c) Urry, G. J. Inorg. Nucl. Chem. 1964, 26, 414. (d) Urry, G.; Nuss, J.
2
W. Angew. Chem., Int. Ed. Engl. 1964, 26, 435. (e)Wiberg, E.; Neumaier, A.
Angew. Chem., Int. Ed. Engl. 1962, 1, 517. (f) Urry, G.; Kaczmarczyk, A.;
Millard, M. J. Inorg. Nucl. Chem. 1961, 17, 186. (g) Urry, G.; Kaczmarczyk,
A. J. Am. Chem. Soc. 1960, 82, 751.
and refined by the full-matrix least-squares techniques on F using the
SHELXTL program (10437 data and 539 parameters). All hydrogen atoms
except hydrogen H71, H72, H81, and H82 were treated as idealized
contributions. All software sources of the scattering factors are contained in
(
3) Boudjouk, P.; Kloos, S. D.; Kim, B.-K.; Page, M.; Thweatt, D. J. Chem.
Soc., Dalton Trans. 1998, 877.
4) Kim, B.-K.; Choi, S.-B.; Kloos, S. D.; Boudjouk, P. Inorg. Chem. 2000,
9, 728.
the SHELXTL v5.1 library (Siemens X-ray Diffraction, 1998, Madison, WI).
2
Final R ) 0.0638, R
w
) 0.1579, and Goodness-of-fit on F ) 1.045 (for all
(
reflections, R ) 0.1329, R ) 0.1967). Full details can be found in the
w
3
Supporting Information.
1
0.1021/ja002831a CCC: $20.00 © 2001 American Chemical Society
Published on Web 07/27/2001