Syntheses of Au(III) and Au(I) Complexes of 3,4,5,6-Tetraphenyl-2,2´-bipyridine

Treatment of the ligand 3,4,5,6-tetraphenyl-2,2´-bipyridine (LH) VIII with HAuCl4 in acetonitrile afforded the cyclometallated square-planar Au(III) complex [LAuCl]ClO4 (7) containing the anionic tridentate (N∧N∧C) ligand, via orthometallation. Treatment of (7) with 4-dimetylaminopyridine (DMAP) and AgClO4 in acetonitrile produced [LAu(DMAP)][ClO4]2 (8), showing the same coordination mode. Analogous complex [LAu(PPh3)][ClO4]2 (9)was prepared by using PPh3 instead of DMAP. Reaction of VIIIwith HAuCl4 at room temperature in aqueous acetonitrileresulted the non-cyclometallated Au(III) complex [(LH)AuCl2]Cl(10), in which VIII is a bidentate (N∧N) ligand. Treatment of VIIIwith the filtrate obtained by mixing [AuCl(PPh3)] and AgO2CCF3 in acetone resulted the non-cyclometallated Au(I) complex[(LH)Au(PPh3)]O2CCF3 (11) having bidentate (N∧N) ligand. Abovecomplexes were adequately characterized by a combination ofelemental analysis, IR, Mass and NMR spectroscopy. The X-raycrystal structures of (7) and (8) were determined.