New Molybdenum(VI) Complexes with Thiosemicarbazone Ligands Containing 4-hydroxy-2-pyrone Ring

Višnja Vrdoljak,^a,* Biserka Prugovečki,^a Marina Cindrić,^a Dubravka Matković-Čalogović^a and Ana Brbot-Šaranović

^a Laboratory of General and Inorganic Chemistry, Chemistry Department, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000 Zagreb, Croatia.
* Corresponding author: E-mail: visnja@chem.pmf.hr
Fax:+385-1-4606341

Abstract
New molybdenum(VI) complexes have been prepared by the reaction of [MoO₂(acac)₂] (acac = acetylacetonate ion) with the thiosemicarbazone ligands derived from dehydroacetic acid and thiosemicarbazide (H₂L¹) or 4-phenylthiosemicarbazide (H₂L²). All complexes consist of the MoO₂²⁺ core with molybdenum coordinated by ligand L via three donor atoms: pyran-4-ol-oxygen, imine-nitrogen and thiol-sulphur. Unlike the monomeric complexes [MoO₂L²D], where the octahedral coordination around the molybdenum atom is achieved by additional coordination of one neutral solvent molecule D (methanol in 2a or ethanol in 2b), in the polymeric complexes [MoO₂L]_n (1 and 2) the octahedral coordination is accomplished by an intermolecular metaloxygen interaction (metal...oxygen//Mo=O···Mo=O). All compounds were characterized by means of elemental analyses, IR spectra, thermal analysis and some of them by X-ray crystallography (ligand HL¹ and complex 2b).

Keywords: Molybdenum(VI) complexes; dehydroacetic acid, thiosemicarbazone; pyrone; crystal structure