SummaryThe catalytic activity of homogeneous and silica-supported rhodium(I) complexes has been investigated for the reaction of tertiary silanols with a series of mono-, di-and triorganosubstituted hydridosilanes. The reaction is very sensitive to the electronic effects of substituents attached to silicon in the hydridosilane. The nature of the catalyst ligands and the structure of organosilanols seem to have little effect on the reaction rate. A mechanism involving rapid activation of the organosilicon hydride in the oxidative addition step followed by nucleophilic attack of the silanol on silicon complexed to rhodium is proposed. The system investigated has also been found to efficiently catalyse the reaction of oligomeric ~,(,)-dihydridopolydinlethylsiloxane with l-~olydimethylsilox-ane-(t,m-diols giving cvclic conapounds. Silica-supported complexes showed lower activity than their homogeneous counterparts.

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