Studies in Group IV organometallic chemistry XXIII. Mechanism of the hydrostannolysis of tin---element bonds

Abstract

The mechanism of the reaction of organotin hydrides with compounds containing a tin---element bond (Sn---N, Sn---P, Sn---As, Sn---O, Sn---S) has been investigated using IR spectroscopic techniques. In reactions involving formation of a tin---tin bond (hydrostannolysis reactions) a polar mechanism is operative as appears from the lack of activity of free radical generators or scavengers and from the influence of the polarity of the solvent on the rate of reaction. Kinetics, isotope effect and the influence of substituent attached to tin and nitrogen on the rate of hydrostannolysis of organotin---nitrogen derivatives indicate electrophilic attack of the organotin hydride hydrogen on nitrogen as the first and rate-determining step. Substituent effects strongly favor an identical mechanism for the hydrostannolysis of organotin---oxygen derivatives.

Exchange reactions predominate hydrostannolysis, if the hetero atom is a second or third row element (S, P, As). The nature of this reaction, which has been studied more closely for organotin---nitrogen derivatives using NMR spectroscopy is discussed.