Dioxomolybdenum(VI) tridentate Schiff base complexes: the role of molybdenum(VI) in obtaining novel dissymmetric polydentate Schiff base ligand

Intensive studies have been carried out during the last decade on the biochemical, pharmacological and physicochemical functions of molybdenum. In particular, many kinds of dioxomolybdenum compounds have been synthesized in order to study the catalytic oxygen atom transfer reactions as model of molybdoenzymes. Our investigations on the molybdenum(VI) complexes with salicylaldehyde and (L-asparagine, L-glutamine, L-ornithine hydrochloride) gave results which confirmed possible catalytic role of molybdenum in oxidative decarboxylation of aminoacids. The reaction of [MoO2(sal)2] and L-asparagine resulted in the yellow crystalline product [Mo2O5(sal-L-Asn)2] (1) and coumarine-3-carboxamide, (2) while in the reaction of [MoO2(sal)2] and L-ornithine (in hydrochloride form) a novel dissymmetric polydentate ligand coordinated to the molybdenum atom was obtained (3). All products were characterized by elemental analyses, IR and NMR data and X-ray analysis (3). We performed computational methods in order to investigate a possible mechanism for the reaction of [MoO2(sal)2] and L-ornithine.