Activation of a C−H Bond in a Pyridine Ring. Reaction of 6-Substituted 2,2‘-Bipyridines with Methyl and Phenyl Platinum(II) Derivatives: N‘,C(3)-“Rollover” Cyclometalation

Abstract

The reaction of the electron-rich derivatives cis-[Pt(R)2(DMSO)2] (R = Me, Ph) with a series of 6-substituted-2,2‘-bipyridines, HL, occurs with loss of methane or benzene, respectively, to yield cyclometalated platinum(II) species [Pt(R)(L)(DMSO)] where L is an anionic ligand N‘,C(3) coordinated. The unusual C−H activation entails a consecutive reaction process through a detectable intermediate. The reaction is peculiar of 6-substituted ligands: for comparison no reaction occurs with 6,6‘-Me2-2,2‘-bipy and an adduct, [Pt(R)2(HL)], is obtained with 5-Me-2,2‘-bipy.