Synthesis, Crystal Structures and Insulin-Enhancing Activity of Vanadium(V) Complexes with Hydrazone Ligands

Two new isostructurally mononuclear vanadium(V) complexes, [VO(L1)(OMe)(MeOH)] (I) and [VO(L2)(OMe)(MeOH)] (II), where L1 and L2 are the dianionic form of 2-chloro-N'-(3,5-dibromo-2-hydroxybenzylidene)benzohydrazide and 2-bromo-N'-(3,5-dibromo-2-hydroxybenzylidene)benzohydrazide, respectively, have been prepared. The complexes have been characterized by physico-chemical methods and single crystal X-ray determination (CIF files CCDC nos. 1824513 (I) and 1824514 (II)). The V atoms in both complexes are coordinated by the three donor atoms of the hydrazone ligands, two O atoms from one deprotonated methanol ligand and one neutral methanol ligand, and one oxo group, forming octahedral coordination. Insulin-mimetic tests on C2C12 muscle cells using biovision glucose assay indicates that the complexes significantly stimulated cell glucose utilization with cytotoxicity at 0.15 g L–1.