Osmium(II) bipyridine (bpy) complexes containing O,O-donor ligands and X-ray crystal structure of the acetylacetonato(acac) complex [Os(bpy)2(acac)](PF6)

The new complexes [Os11(bpy)2L](PF6) [bpy = 2,2′-bipyridine; HL = acetylacetone (Hacac), trifluoroacetylacetone (Htfacac), hexafluoroacetylacetone, dibenzoylmethane or tropolone] have been prepared and the chemical oxidation of the [OsII(bpy)2L]+ species (L = acac or tfacac) by aqueous S 2 O 8 2 - solution in the presence of (NH4)PF6 gave the reddish brown complexes [OsIII(bpy)2L](PF6)2. These complexes were characterized by spectroscopic measurements and also investigated by cyclic voltammetry. The X-ray crystal structure of [Os(bpy)2(acac)](PF6) (1) has been determined and showed that the complex has a distorted octahedral geometry in an environment of N4O2 donors. The reactivity toward oxidation of benzyl alcohol by complex (1) using H2O2 or other co-oxidants has been studied and compared with that of the related ruthenium(II) complexes.