NMR and theoretical study on the coordination interactions between peroxovanadium(V) complex and bisubstituted pyridine ligands

To understand the substitution effects of pyridine ligands on coordination equilibrium, the coordination interactions between a series of bisubstituted pyridine ligands and peroxovanadium(V) [OV(O-2)(2)(D2O)](-)/[OV(O-2)(2)(HOD)](-) in solution have been investigated by multinuclear (H-1, C-13, and V-51) magnetic resonance and HSQC. A series of new six-coordinate peroxovanadate complexes [OV(O-2)(2)L] (n) (-) (L=2, 3, 4, n=1 or 3) have been observed, and the coordination ability of the bisubstituted pyridines to peroxovanadium(V) is 3,4-dimethylpyridine (2)>3,5-dimethylpyridine (3)>pyridine-3,5-dicarboxylate (4)>> 2,3-dimethylpyridine (1). The coordination interactions among title system have been further studied by DFT (density functional theory) calculations, and the results indicate that solvent may play an important role in these coordination interactions.