ELECTROGENERATION OF TRIPHENYLTIN RADICAL, ANION, AND CATION - ELECTROCHEMICAL INITIATION OF TIN HYDRIDE-PROMOTED RADICAL-CHAIN REACTIONS

In our research of precursors of tin radicals able to initiate radical chain reactions under mild conditions, a series of triphenyltin deriv atives Ph(3)SnY (Y = H, I, Cl, OTf, OCHO, SnPh(3), SPh) is investigate d by cyclic voltammetry. The results show that the tin radical Ph(3)Sn (.) is only produced from two compounds: by a one-electron oxidation o f Ph(3)SnH or by a one-electron reduction of Ph(3)SnI. Therefore elect rooxidation of Ph(3)SnH generates Ph(3)Sn(.) which is able to initiate cyclization of haloalkynes. Reduction or oxidation of the other deriv atives affords respectively the anion Ph(3)Sn(-) or the cation Ph(3)Sn (+) because they are generated at potentials where the radical Ph(3)Sn (.) is either reduced or oxidized.