Preparation and electrochemistry of six-coordinate monooxo molybdenum(VI) complexes containing bidentate catecholate and tridentate NOS-donor Schiff base ligands

Abstract

The preparation, characterization and electrochemical properties are reported for monooxo Mo(VI) complexes, MoO(cat)(ssp), containing bidentate catecholate (cat 2 = 3,5-di-tert-butylcatecholate, naphthalene-1,2-diolate, phenanthrene-9,10-diolate) and tridentate NOS-donor Schiff base (ssp 2 = N-salicylidene-2-aminobenzenethiolate) ligands. The intensely colored compounds are formed by oxo abstraction from MoO 2(ssp) with EtPh 2P in THF followed by oxidative addition of the appropriate quinone. Oxo abstraction leads to a mixture of MoO(ssp) and Mo 2O 3(ssp) 2 rather than either of these single products under the experimental conditions. The six-coordinate MoO 4+ species exhibit reversible Mo(VI/V) electrochemistry at a potential ∼0.1 V more positive than that for analogous complexes with the NOO′-donor Schiff base ligand N-salicylidene-2-aminophenolate (sap 2−).