Structure and fluxional behaviour of the adducts of orthoquinones with organotin halides. An electron spin resonance study

Abstract

Free radicals observed in reactions of acenaphthoquinone (AQ) and benzo[2,1-b;3,4-b′]dithiophen-4,5-dione (TQ) with the series of compounds Sn Ph_nX_4–n(n= 3, XH, Cl;n= 2, XCl,n= 0, XCl) have been characterised by e.s.r. spectroscopy. Coupling to only a single chlorine nucleus is detectable in radical adducts containing two or three chlorine atoms. The implications of this observation are discussed in terms of structures involving a five-coordinate tin atom. Activation parameters are reported for the intramolecular migration of SiPh₃ and GePh₃ groups between the oxygen atoms of TQ.