Catalytic oxidation of organosulfides to sulfoxides using two novel Cu(II) and Ni(II) complexes with aqueous H2O2: Effect of TMAO promoter on oxidation of organosulfides

Two new copper(II) and nickel(II) complexes [Cu(MeOH)(O–NO2)(L)](NO3)·CH3OH (1) and [Ni(L)2(NO3)2]·H2O (2) derived from the 4′-(2-thienyl)-2,2′,6′,2″-terpyridine (L) were synthesized. The ligand and complexes were characterized with elemental analysis, 1H and 13C NMR, IR spectroscopy and finally the solid structure of complexes were determined by X-ray crystallography. Complexes (1) and (2) were tested as homogenous catalysts for sulfoxidation of a variety of organosulfide substrates utilizing hydrogen peroxide in the presence of a catalytic amount of trimethylamine N-oxide (TMAO). Addition of TMAO to the reaction mixture enhanced the conversion and selectivity.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (49 K)Download as PowerPoint slideResearch highlightsCrystal structures of two new copper(II) and nickel(II) complexes were determined. These complexes were shown catalytic activity for sulfoxidation of a variety of organosulfide substrates.