The mechanism of protonolysis of phenylplatinum(II) bonds in complexes with phenyl trans to nitrogen or carbon donors

Abstract

Addition of acids of the form HX (X = Cl, BF4, CF3SO3, CF3CO2) to complexes [PtPh2(NN)] (NN = bu2bpy = 4,4'-di-tert-butyl-2,2'-bipyridine) and [PtPh(NCN)] (NCN = 2,6-C6H3(CH2NMe2)2) at –78 °C gave the corresponding phenyl(hydrido)platinum(IV) complexes [PtX(H)Ph2(NN)] and [PtX(H)Ph(NCN)], which decomposed by reductive elimination of benzene at about –20 °C to give the platinum(II) complexes [PtXPh(NN)] and [PtX(NCN)]. Further addition of HCl to [PtClPh(NN)] at low temperature gave [PtHCl2Ph(NN)], which decomposed above –10 °C, to give benzene and [PtCl2(NN)]. The reaction of DBF4 in the presence of excess CD3OD with [PtPh2(NN)] led to formation of C6H5D and C6H4D2 but with [PtPh(NCN)] no multiple deuterium incorporation was observed in the product benzene. The mechanisms of these reactions are discussed. Key words: platinum, phenyl, benzene, protonolysis.