PREPARATION AND ELECTROCHEMISTRY OF 6-COORDINATE MONOOXO MOLYBDENUM(VI) COMPLEXES CONTAINING BIDENTATE CATECHOLATE AND TRIDENTATE NOS-DONORSCHIFF-BASE LIGANDS

The preparation, characterization and electrochemical properties are r eported for monooxo Mo(VI) complexes, MoO(cat) (ssp),containing bident ate 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 i ntensely colored compounds are formed by oxo abstraction from MoO2 (ss p) with EtPh2P in THF followed by oxidative addition of the appropriat e quinone. Oxo abstraction leads to a mixture of MoO(ssp) and Mo2O3(ss p)(2) rather than either of these single products under the experiment al conditions. The six-coordinate MoO4+ species exhibit reversible Mo( VI/V) electrochemistry at a potential similar to 0.1 V more positive t han that for analogous complexes with the NOO'-donor Schiff base ligan d N-salicylidene-2-aminophenolate (sap(2-)). (C) 1998 Elsevier Science S.A. All rights reserved.