Oxidative addition to diplatinum(II) complexes: Stereoselectivity and cooperative effects

The stereochemistry of oxidative addition of MeI and MeO3SCF3 to binuclear dimethylplatinum(II) complexes containing bis(bidentate) ligands such as cis- and trans-1,2-C6H10-(N=CH-2-C5H4N)(2), 1 and 2a, has been studied. Oxidative addition of the Me-X bond (X = I or CF3SO3) occurred at both dimethylplatinum centers, often with high stereoselectivity, to give bis(trimethylplatinum(IV)) complexes. Two types of adducts were formed, either neutral complexes containing {PtMe3X}(2) groups or ionic complexes containing [(PtMe3)2(mu-X)]X-+(-) groups. When X = iodide, both forms were detected, but when X = triflate, the ionic form with one bridging triflate ligand dominated. The triflate ligand was easily displaced by water to give an aqua complex, and reaction of NaBH4 with cis-1,2-[C6H10{N=CH-2-C5H4N(PtMe3)}(2)(mu-O3SCF3)][O3SCF3] gave the platinum(IV) borohydride complex cis-1,2 [C6H10{N=CH-2-C5H4N(PtMe3)}(2)(mu-BH4)][O3SCF3] as a single diastereomer. Addition of PPh3, to trans-1,2-[C6H10{N=CH-2-C5H4N(PtMe3)}(2)(mu-OSCF3)][O3SCF3] gave C-2-symmetric trans1,2-[C6H10{N=CH-2-C5H4N(PtMe3PPh3)}(2)][O3SCF3](2,) with a change in absolute configuration.