Interactions of cobalt tetrasulfophthalocyanine with thiolate anions in dimethylformamide

• Published in: Journal of porphyrins and phthalocyanines 2001-04, Vol.5 (4), p.405-414
• Main Authors: Tyapochkin, Eduard M., Kozliak, Evguenii I.
• Format: Article
• Language: English
• Subjects: autoxidation; cobalt tetrasulfophthalocyanine; Merox process; thiolates
• ISSN: 1088-4246; 1099-1409
• DOI: 10.1002/jpp.341

Thiolate complexes of cobalt tetrasulfophthalocyanine (CoTSPc), possible intermediates of the industrial removal of mercaptans from oil fractions (Merox process), were studied in dimethylformamide, dimethylsulfoxide, and other polar aprotic solvents by UV‐vis, 1H NMR, and ESR spectroscopy. All thiolates react with CoIITSPc under anaerobic conditions with 1:1 stoichiometry. All tested aliphatic thiolates, regardless of their basicity, reduce CoIITSPc to form CoITSPc derivatives. Low‐basicity thiolates also form unstable non‐reduced (RS−)CoIITSPc complexes as dead‐end products. Indirect kinetic evidence was obtained for electron transfer from the axial ligand to metal via the phthalocyanine equatorial ligand. 1H NMR and binding studies revealed sulfur–cobalt interactions in the CoITSPc product, thus indicating an axial ligand attachment to CoITSPc. Low‐basicity aromatic thiolates (pentachloro‐ and pentafluorobenzenethiolate) form (RS−)CoIITSPc complexes, which are stable toward intramolecular metal reduction. This effect is indicative of possible π‐stacking between the aromatic thiolate and phthalocyanine ring. Copyright © 2001 John Wiley & Sons, Ltd.