Novel dioxomolybdenum(VI) and oxomolybdenum(V) complexes with pyridoxal thiosemicarbazone ligands: Synthesis and structural characterisation

New molybdenum complexes were prepared by the reaction of [MoVIO2(acac)2] or (NH4)2[MoVOCl5] with different N-substituted pyridoxal thiosemicarbazone ligands (H2L1 = pyridoxal 4-phenylthiosemicarbazone; H2L2 = pyridoxal 4-methylthiosemicarbazone, H2L3 = pyridoxal thiosemicarbazone). The investigation of monomeric [MoO2L1(CH3OH)] or polymeric [MoO2L1–3] molybdenum(VI) complexes revealed that molybdenum is coordinated with a tridentate doubly-deprotonated ligand. In the oxomolybdenum(V) complexes [MoOCl2(HL1–3)] the pyridoxal thiosemicarbazonato ligands are tridentate mono-deprotonated. Crystal and molecular structures of molybdenum(VI) [MoO2L1(CH3OH)]·CH3OH, and molybdenum(V) complexes [MoOCl2(HL1)]·C2H5OH, as well as of the pyridoxal thiosemicarbazone ligand methanol solvate H2L3·MeOH, were determined by the single crystal X-ray diffraction method.