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Defined crystalline amino-substituted organosilanes were prepared by reaction of N-methylaniline with 1,1,2,2-tetrachloro-1,2-dimethyldisilane. It is possible to selectively prepare mono-, di-, and triaminodisilanes depending on the reactant ratio. The X-ray structure analyses of 1,2-dichloro-1,2-dimethyl-1,2-bis(N-methylanilino)disilane (2), 1-chloro-1,2-dimethyl-1,2,2-tris(N-methylanilino)disilane (3), and 1,2-dimethyl-1,1,2,2-tetrakis(N-methylanilino)disilane (4) were performed. The absolute structure of 2 was determined by crystallographic methods. Compound 2 is a useful reagent for preparing a variety of other aminoorganodisilanes like

Disproportionation reactions of chlorosilane compounds in the presence of boron trichloride yield the compound H[B(SiCl 3 ) 4 ]. Spectroscopic analyses of the yellow-whitish solid with IR-, Raman-, and NMR-spectroscopy ( 29 Si, 11 B) show the presence of a highly symmetric anion containing boron, which is fourfold coordinated with silicon. Due to the high symmetry 1 J( 11 B, 29 Si) and even 1 J ( 10 B, 29 Si) couplings can be observed in the NMR spectra of the dissolved compound. The crystal structure analysis with a crystal obtained from toluene solution proves the existence of a highly symmetric borate anion, which is stabilized by four trichlorosilyl groups. The molecular structure consists of a para-protonated toluene cation and the weakly coordinating borate anion [B(SiCl 3 ) 4 ] À . Quantum chemical analysis of the tetrakis(trichlorosilyl)borate ion shows a negatively charged boron atom and the presence of polar SiÀ Cl and SiÀ B bonds. Highly reactive compounds [E(SiCl 3 ) n ] À which are stabilized solely by trichlorosilyl groups have been prepared with E=C, Si, Ge, P, S in recent years. The superacid H[B(SiCl 3 ) 4 ] represents a new member in this elusive compound family.

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