REACTIVITY STUDIES OF SULFUR-BRIDGED MOLYBDENUM DIMERS CONTAINING ELECTRON-WITHDRAWING DITHIOLATE SUBSTITUENTS

New complexes of the formula (Cp'Mo(mu-S))2S2CHR, where R = CO2Me (3) and CO2Na (4) (Cp' = C5H5, CH3C5H4), have been synthesized and characterized spectroscopically. Their reactions have been compared to those of the parent compound, where R = H (1). The synthesis of 3 involved the alkylation of (MeCpMo)2(mu-S2) (mu-S)2 with BrCH2CO2Me to form [(MeCPMO)2-(mu-S2)(mu-S)(mu-SCH2CO2Me)]Br (2(Br)). Complex 2 crystallized in space group P2(1)/c with a = 10.379(2) angstrom, b = 20.820(6) angstrom, c = 9.597(2) angstrom, beta = 102.56-degrees, V = 2024.3(8) angstrom3, and Z = 4. An X-ray diffraction study of 2 confirmed that a mu-sulfido ligand was the site of alkylation and the mu-S2 ligand remained intact. Complex 2 was deprotonated on an alumina column to form 3. The water-soluble complex 4 was synthesized by the reaction of [Cp'Mo(mu-S)(mu-SH)]2 With Br2-CHCO2Na in the presence of base. The reactivities of 3 and 4 are similar to that of 1 in most cases. Unlike 1, complex 3 reacts with triflic acid to cleave a C-S bond of the dithiolate ligand and form the triflate salt of 2. Complex 4 differs from 1 in that it undergoes an observable reaction with hydrogen in neutral or basic aqueous solution. Spectroscopic data for the hydrogen addition product are consistent with the formulation (CpMo)2(mu-S)2(mu-SH)(mu-SCH2CO2Na) (7). The catalytic activity of 4 and 7 for D2-H2O exchange and for the hydrogenation of C = N and N = N bonds in two-phase aqueous/organic solvent systems has been studied.