Synthesis and Characterization of Palladium(II) and Platinum(II) Adducts and Cyclometalated Complexes of 6,6 '-Dimethoxy-2,2 '-bipyridine: C(sp(3))-H and C(sp(2))-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.