Synthesis, Characterization, and Catalytic Performance in Oxidation of Styrene and α-Methyl Styrene of a Nickel(II) Complex Derived from a Schiff Base Ligand

A tetrahedrally-distorted square-planar nickel(II) complex of tetradentate Schiff base ligand derived from 2-hydroxypropiophenone and 2,2'-dimethylpropandiamine [bis(2-hydroxypropiophenone) 2,2'-dimethylpropylenediimine] (H2L) was prepared and used as catalyst for oxidation of styrene and a-methyl styrene with tert-butylhydroperoxide (TBHP). Oxidation of styrene with TBHP gave benzal-dehyde and styrene oxide, but in the case of alpha-methylstyrene a mixture of a-methylstyrene oxide and acetophenone was obtained. The structure of nickel(II) complex (NiL) was determined by X-ray crystallography. Crystal data for NiL at -173 degrees C: orthorhombic, space group P2(1)2(1)2(1), a = 907.7(1), b = 1289.4(1), c = 1752.4(1) pm, Z = 4, R-1 = 0.0454.