Oxidative Addition of Ph2TeCl2 to a Dimethylplatinum(II) Complex: Effects of Secondary Bonding in the Platinum-Tellurium Products

In the first example of oxidative addition of tellurium-halide bonds to a transition-metal complex, Ph2TeCl2 reacts with [PtMe2(bu2bpy)], 1, bu2bpy = 4,4ʹ-di-tert-butyl-2,2ʹ-bipyridine, to give an organoplatinum(IV) complex that can be formulated as an ionic diphenyl telluride complex [PtClMe2(TePh2)(bu2bpy)]Cl or as a neutral chlorodiphenyltelluryl complex [PtClMe2(TePh2Cl)(bu2bpy)]; the complex contains an unusually long Te···Cl bond length of 3.43 (angstrom). The weakly bound chloride ligand is easily removed by reaction with AgO3SCF3 to give the cationic complex [PtClMe2(TePh2)(bu2bpy)](CF3SO3) in which the triflate anion is not coordinated to tellurium. This complex reacts with a second 1 equiv of AgO3SCF3 to give the aqua complex [PtMe2(OH2)(TePh2..O3SCF3)(bu2bpy)](CF3SO3), in which a triflate anion forms secondary bonds with both the aqua and TePh2 ligands. In these platinum(IV) complexes, the magnitude of the coupling constant 1J(PtTe) is strongly influenced by the presence of the weakly bonded Te···X groups.