Synthesis and structure of silicon compounds intramolecularly coordinated by hydrazino groups

Organosilicon compounds bearing the 2-(trimethylhydrazincmethyl)phenyl and 2-(trimethylhydrazino)phenyl substituent have been prepared by treatment of the corresponding aryllithium with Me3SiCl and SiCl4. Subsequent reactions of chlorositanes 10, 15, 18, and 22 afforded a variety of functionalized silanes. NMR spectroscopic data of most 2-(trimethylhydrazino)phenyl substituted silanes indicate a highly coordinated silicon center in solution. Diethoxy compound 20 is hexacoordinate in the solid state due to interaction with the hydrazino groups of both aromatic substituents, whereas in dichlorosilane 22 only the amino group of the 2-(trimethylhydrazino)phenyl substituent coordinates to the silicon center. The coordinating ability of the 2-(trimethylhydrazino)phenyl substituent has been used to stabilize silyl cations by formation of pentacoordinate siliconium ions 33 and 34. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.