Reactions of Five-Coordinate Platinum(IV) Complexes with Molecular Oxygen

The reactions of various five-coordinate Pt­(IV) complexes with molecular oxygen have been studied. In arene solution, the complexes (tBuMe2nacnac)­PtMe3 (1; tBuMe2nacnac– = [((4-tBu-2,6-Me2C6H2)­NC­(CH3))2CH]−), (Me3Me-nacnac)­PtMe3 (2; Me3Me-nacnac– = [((2,4,6-Me3C6H2)­NC­(CH3))2CCH3]−), and (tBu2PyPyr)­PtMe3 (3; tBu2PyPyr– = 3,5-di-tert-butyl-2-(2-pyridyl)­pyrrolide) reacted immediately with oxygen to form peroxo species in which two oxygen atoms bridge between the metal center and a carbon atom in the ligand backbone. In contrast, no reaction between (iPr2AnIm)­PtMe3 (4a; iPr2AnIm– = [o-C6H4-{N­(C6H3iPr2)}­(CHNC6H3iPr2)]−) or (Me3AnIm)­PtMe3 (4b; Me3AnIm– = [o-C6H4-{N­(C6H2Me3)}­(CHNC6H2Me3)]−) and oxygen was observed. As activation of oxygen by five-coordinate Pt­(IV) species was found to involve cooperation between the metal center and the ligand, the ability of the ligand to participate in the oxygen binding appears to be a vital component. Oxygen atom transfer reactions of the novel peroxo species are also presented.