Modelling nucleophilic substitution at silicon using hypervalent silicon compounds based on di and tri halosilanes

The Si-29- and C-13-NMR spectral parameters of a range of N-(amidomethyl)-p olyhalosilanes have been measured in solution and the extent of Si-O bond f ormation and pentacoordination determined. The larger the number of electro negative groups attached to the silicon the greater the extent of pentacoor dination achievable by the silicon. Thus with trichlorosilanes a 'tight' pe ntacoordinate silicon is observed where the Si-O bond is almost fully forme d. (C) 2000 Published by Elsevier Science S.A. All rights reserved.