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 (bipy(2OMe)) with palladium(II) and platinum(II) chlorides or acetates afforded either neutral, [M(bipy(2OMe))Cl-2], and cationic, [Pt(bipy(2OMe))(2)] [Pt(DMSO)Cl-3](2), adducts or cyclo-metalated derivatives [M(bipy(OMe,OCH2))X] and [M(bipy(2OME)-H)X](2) (M = Pd, X = OAc, Cl; M = Pt, X = Cl) arising from respectively C(sp(3))-H and C(sp(2))-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 (bipy(OME,OH)) arising from monodemethylation of bipy(2OME), were also formed as coproducts under certain reaction conditions. The crystal structures of [Pt(bipy(2OMe))(2)] [Pt(DMSO)Cl-3](2) and of [Pd-(bipy(2OMe)-H)(OAc)](2) have been solved by X-ray crystallography.