Platinum(II), palladium(II) and gold(III) adducts and cyclometalated derivatives of 6-methoxy-2,2′-bipyridine: A comparative study.

Reaction of 6-methoxy-2,2′-bipyridine (bpy 6OMe ) with the electron-rich platinum(II) complex [Pt(Me) 2 (DMSO) 2 ] gave the rollover cyclometalated complex [Pt(κ 2 -N,C-bpy 6OMe -H) (Me) (DMSO)] under mild conditions. The occurrence of rollover cyclometalation was demonstrated by single crystal X-ray diffraction structure determination. In contrast, reaction of bpy 6OMe with [Pt(Ph) 2 (DMSO) 2 ] and [Pt(Cl) 2 (DMSO) 2 ] under mild conditions gave only adduct species of the type [Pt(X) 2 (bpy 6OMe )] (X = Ph, Cl). Under harsher conditions, activation of a C H bond in the methoxy substituent yielded the terdentate cyclometalated complex [Pt (κ 3 -N,N,C-bpy 6OMe -H)Cl]. Finally, reaction of Pd(II) and Au(III) derivatives invariably gave adduct species, with the exception of the dimeric complex [Pd(κ 2 -N,C-bpy 6OMe -H) (OAc)] 2 , which, however, was not isolated in pure form. The reactivity of bpy 6OMe , as emerged from this study, was compared with that of the corresponding disubstituted ligand 6,6′-dimethoxy-2,2′-bipyridine, previously studied by us. [ABSTRACT FROM AUTHOR]