Molybdenum chemistry has received the intense attention because of its relevance to the active sites of molybdoenzymes. The presence of the cis-dioxo-, in the oxidized forms of certain molybdoenzymes has stimulated both the search for new structures in which this moiety is coordinated to ligands containing nitrogen, oxygen and/or sulfur donors and also the study of their chemical, spectroscopic, electrochemical and structural properties.
1-5Tridentate ONS-chelating ligands derived from thiosemicarbazide or dithiocarbazate of salicylaldehyde have been widely used in much of this work.
6-9The tautomerism (Scheme 1) of these ligands as well as the well known tendency of sulfur donors to act as bridging ligands allows various structural possibilities for the corresponding metal complexes.As part of our studies on the coordination chemistry of d-block metal complexes with Schiff base ligands, we have earlier described the synthesis and spectroscopic and electrochemical properties for the molybdenum(VI) complexes, such as [MoO