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

New molybdenum complexes were prepared by the reaction of [(MoO2)-O-VI(acac)(2)] or (NH4)(2)[(MoOCl5)-O-V] 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)]center dot CH3OH, and molybdenum(V) complexes [MoOCl2(HL1)]center dot C2H5OH, as well as of the pyridoxal thiosemicarbazone ligand methanol solvate H2L3 center dot MeOH, were determined by the single crystal X-ray diffraction method. (C) 2009 Elsevier B. V. All rights reserved.