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.