Different reaction behaviour of molybdenum and tungsten - Reactions of the dichloro dioxo dimethyl-bispyridine complexes with thiophenolate

摘要

The reaction of the metal complexes MO2Cl2(mebipy) (M = Mo, W) with two equivalents thiophenol by the exact same procedure leads to two different products for molybdenum [Mo2O4(SPh)(2)(mebipy)(2)] and tungsten [WO2(SPh)2(mebipy)]. To understand why this is the case the redox potentials of the starting materials were measured showing that the redox potential for thiophenol is lower than the redox potentials (M-v <-> M-vi) for both of the metal precursors. A reduction of the metal and oxidation of the sulfur should be possible for both reactions but occurs only for the molybdenum compound. Theoretical calculations show that different metal-sulfur bond strengths are as well and equally responsible for the differing reaction behaviour as are the redox potentials. (C) 2007 Elsevier B.V. All rights reserved.