HALOMETHYLMETAL COMPOUNDS .17. MECHANISM OF DICHLOROCARBENE INSERTION INTO SI-H BOND BY MERCURIAL ROUTE

The reaction of phenyl(bromodichloromethyl)mercury with triethylsilane in benzene at 39.0° was found to be about first order in mercurial and zero order in triethylsilane, and the mechanism shown by eq 6 and 7, which involves a dichlorocarbene intermediate, was suggested. A Hammett study of the reaction of this mercurial reagent with substituted aryldimethylsilanes gave relative rate constants which showed good correlation with and gave a ρ value of -0.632 ± 0.032. Electrophilic attack by CCl2 at the Si-H bond in which there is not high separation of charge in the transition state is indicated. The reaction of triethyldeuteriosilane with PhHgCCl2Br in benzene and in methylene chloride solution gave only Et3SiCCl2D. These observations and others made by Sommer and Ritter and by us in previous studies lead us to favor transition state III for the insertion of CCl2 into the the Si-H bond. © 1968, American Chemical Society. All rights reserved.