Synthesis and Characterization of Palladium(II) and Platinum(II) Adducts and Cyclometalated Complexes of 6,6′-Dimethoxy-2,2′-bipyridine: C(sp3)–H and C(sp2)–H Bond Activations

Reactions of 6,6′-dimethoxy-2,2′-bipyridine (bipy2OMe) with palladium(II) and platinum(II) chlorides or acetates afforded either neutral, [M(bipy2OMe)Cl2], and cationic, [Pt(bipy2OMe)2][Pt(DMSO)Cl3]2, adducts or cyclometalated derivatives [M(bipyOMe,OCH2)X] and [M(bipy2OMe-H)X]2 (M = Pd, X = OAc, Cl; M = Pt, X = Cl) arising from respectively C(sp3)–H and C(sp2)–H bond activation, depending on the metal precursor, solvent, and other reaction conditions. Cyclometalated complexes of the new ligand 6-hydroxy-6′-methoxy-2,2′-bipyridine (bipyOMe,OH), arising from monodemethylation of bipy2OMe, were also formed as coproducts under certain reaction conditions. The crystal structures of [Pt(bipy2OMe)2][Pt(DMSO)Cl3]2 and of [Pd(bipy2OMe-H)(OAc)]2 have been solved by X-ray crystallography.