CHEMISTRY OF MOLYBDENUM WITH HARD-SOFT DONOR LIGANDS .3. OXOMOLYBDENUM(VI) AND CIS-DIOXOMOLYBDENUM(VI) MIXED-LIGAND COMPLEXES

The syntheses and characterization of a number of oxomolybdenum(VI) and cis-dioxomolybdenum(VI) complexes with 4-substituted thiosemicarbazides in the form of 4-phenyl, 4-(p-methylphenyl) and 4-(p-chlorophenyl)thiosemicarbazide (represented as LH) as the NS donor metal binding substrates are described. The oxomolybdenum(VI) complexes are of the type MoO(NS)2X2 and MoO(NS)2(OO) (where X = Br or SCN and OO = oxalate or malonate) with a pentagonal bipyramidal geometry. The cis-dioxomolybdenum(VI) complexes are mixed chelate complexes, MoO2(NS)L′, where L′H is either a monoprotic NO donor like oxine, 2-methyloxine or a NS donor such as 2-aminobenzenethiol, 2-aminocyclopent-1-ene-1-dithiocarboxylic acid and its methyl ester. The electrochemical behaviour of these complexes along with cis-MoO2(NS)2 and MoO(NS)2Cl2 complexes are discussed. © 1990.