Syntheses, magnetic properties, and reactivity of dinuclear oxovanadium (IV) and copper (II) complexes with (μ-diphenylphosphinato)-bridges

Novel dinuclear oxovanadium (IV) complexes having the formula [(VO)2(dpp)3(bpy)2]NO3·2H2O (1), [(VO)2(dpp)3(phen)2]-NO3·H2O (2), [(VO)2(bmp)3(bpy)2]NO3·H2O (3), and [(VO)2(bmp)3(phen)2]NO3·H2O (4), and copper (II) complexes having the formula [Cu2(bmp)2(phen)2](NO3)2·MeOH·H2O (5), and [Cu2(bmp)2(bpy)2](NO3)2 (6) (where Hdpp=diphenylphosphinic acid, Hbmp=bis(4-methoxyphenyl)phosphinic acid, bpy=2,2′-bipyridine, and phen=1,10-phenanthroline) with (μ-phosphinato)-bridges, 1–6, have been prepared and characterized. Crystal structure of complex 2 reveals that two vanadium ions are linked by tris(μ-phosphinato)-bridges. The magnetic susceptibility data for 1–3, and 6 conform to the usual dimer equation with −2J values of 16–24 cm−1, indicating a weak antiferromagnetic interaction between vanadium(IV) ions. The oxidation of cinnamyl alcohol was studied using complexes 1–6 as catalyst and molecular oxygen as an oxidant. In the presence of complex 3 as a catalyst, cinnamyl alcohol was oxidized to cinnamaldehyde 61% yield in 7 h. Consequently, complex 3 activates oxygen, and then alcohol was quite efficiently oxidized by activated oxygen.