Interactions of cobalt tetrasulfophthalocyanine with thiolate anions in dimethylformamide

Thiolate complexes of cobalt tetrasulfophthalocyanine (CoTSPc), possible in termediates of the industrial removal of mercaptans from oil fractions (Mer ox process), were studied in dimethylformamide, dimethylsulfoxide, and othe r polar aprotic solvents by UV-vis,H-1 NMR, and ESR spectroscopy. All thiol ates react with Co(II)TSPe under anaerobic conditions with 1:1 stoichiometr y. All tested aliphatic thiolates, regardless of their basicity, reduce (Co TSPc)-T-II to form (CoTSPc)-T-I derivatives. Low-basicity thiolates also fo rm unstable non-reduced (RS-)Co(II)TSPe complexes as dead-end products. Ind irect kinetic evidence was obtained for electron transfer from the axial li gand to metal via the phthalocyanine equatorial ligand. H-1 NMR and binding studies revealed sulfur-cobalt interactions in the (CoTSPc)-T-I product, t hus indicating an axial ligand attachment to (CoTSPc)-T-I. Low-basicity aro matic thiolates (pentachloro- and pentafluorobenzenethiolate) form (RS-)Co( II)TSPe complexes, which are stable toward intramolecular metal reduction. This effect is indicative of possible pi -stacking between the aromatic thi olate and phthalocyanine ring. Copyright (C) 2001 John Wiley & Sons, Ltd.