(pentabenzylcyclopentadienyl)molybdenum complexes : Synthesis, structures and redox properties

[MCpBz(CO)3]2 (M = Mo 3, W 4; CpBz = pentabenzylcyclopentadienyl) complexes were prepared by reaction of Li[MCpBz(CO)3] [M = Mo (1), W (2)] with FeIII. [MoCpBz(CO)2]2 (5) can be prepared by thermal elimination of CO from 3 and also by reaction of 1 with C3H5Br. The steric bulk of the CpBz ligands causes all the dimers to exist either in the solid state or in solution as the trans isomers. The hydrido complexes [MH(CpBz)(CO)3] [M = Mo (6), W (7)] were prepared by reactions of 1 and 2 with H+. Cyclic voltammetry and controlled potential coulometry of 5 in CH2Cl2, thf and CH3CN were performed and mechanisms for the redox behaviour are proposed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)