One-electron oxidations and reductions of organomercurials and organotins
Do, Sang Rok
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Single ectron-transfer (SET) oxidations of alkylmetals in the lead, mercuiy and tin series have been studied extensively by Kochi and co-workers. Substantial evidence for both iimer and outer electron transfer in oxidations by, for example, hexachlo[oiridate(IV) and tris(l,10-phenanthroline)iron(III) complexes, leading to the fcvmation of alkyl radicals, has been provided. Recently, Shine and co-workers have found evidence for SET in reactions of thianthrene cation radical perchlorate fTh'''*G04~) with aiyllithiums, aryl- and alkyl Grignard reagents,2 dialkylmercurials, and tetraalkyl- and tetraaiyltins.^ In contrast, it was also found from more recent work that reactions of diarylmercurials with Th'*'*Q04~ showed the lack of signs of radical formation through SET. The objective of this study was to characterize the chemistry of electron transfer by the reaction of cation radicals of tris(p-bromophenyl)mine, tris(p-chlorophenyl)amine and tris(p-cart>omethoxyphenyl)amine with symmetrical diaiylmercurials (Ar^Hg), in which Ar = phenyl, o-tolyl, p-tolyl, o-anisyl, p-anisyl and o-allyloxyphenyl. In the reactions of tris(l,10-phenanthroline)iron(III) complex with diarylmercurials such as diphenylmercury, di(o-alIyloxyphenyl)mercuiy and di(2-allyloxy-4,5-dimethylphenyl)mercury, the object was to find if one-electron oxidation by a transition metal complex could generate aryl radicals, and whether the aryl radicals could be trapped or scavenged. The purpose of studying the reactions of tetranitromethane with diaryhnercurials was to probe the validity of the aiyl radical mechanism which had been proposed earlier for the formation of aromatic hydrocarbons in the reactions of tetranitromethane and halogenotrinitromethanes with diphenyl- and dimesitylmercury) and with tetraphenyltin.