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, BF 4 , CF 3 SO 3 , CF 3 CO 2 ) to complexes [PtPh 2 (NN)] (NN = bu 2 bpy = 4,4'-di-tert-butyl-2,2'-bipyridine) and [PtPh(NCN)] (NCN = 2,6-C 6 H 3 (CH 2 NMe 2 ) 2 ) at –78 °C gave the corresponding phenyl(hydrido)platinum(IV) complexes [PtX(H)Ph 2 (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 [PtHCl 2 Ph(NN)], which decomposed above –10 °C, to give benzene and [PtCl 2 (NN)]. The reaction of DBF 4 in the presence of excess CD 3 OD with [PtPh 2 (NN)] led to formation of C 6 H 5 D and C 6 H 4 D 2 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.