Olefin epoxidation catalyzed by novel nickel(II)-complexes containing tridentate Schiff-base ligands

Abstract

Novel Schiff base complexes of nickel(II), [NiL₁(H₂O)] (<b>1</b>)

{H₂L₁= N-(2-hydroxyphenyl)salicylaldimine}, [NiL₂(H₂O)] (<b>2</b>)

{Happ = N-(2-hydroxyphenyl) pyridine-2-carboxaldimine}, [NiL₃(H₂O)] (<b>3</b>) {N-(2-carboxyphenyl )salicylald imine}and [NiL₄(H₂O)] (<b>4</b>) {N-(2-carboxyphenyl)pyridine-2-carboxaldimine ) have been prepared and characterized by physico-chemical analysis. Complexes <b>1-4</b> are found to be active in catalyzing hydrocarbon oxidation in the presence of single oxygen atom donors. Efficiency of NiL complex towards catalysing epoxidation of olefins in the presence of various oxidants viz. NaOCl, KHSO₅, H₂O₂, pyridine N-oxide (PyO), <i>t</i>-BuOOH, etc., has been examined and it is found that the complexes <b>1-4</b> can effectively catalyze the epoxidation of olefins in the presence of NaOCl and KHSO₅.