Synthesis, Characterization and X-Ray Crystal Structures of cis-Dioxomolybdenum(VI) Complexes of Similar Tridentate Aroylhydrazone Schiff Bases with Catalytic Epoxidation Activity

Abstract

Two new cis-dioxomolybdenum(VI) complexes with general formula [MoO₂LMeOH], where L = L¹ = N’-(3,5-dibromo-2-hydroxybenzylidene)-4-trifluoromethylbenzohydrazide for complex (1), and L = L¹ = N’-(3-bromo-5-chloro-2-hydroxybenzylidene)-4-trifluoromethylbenzohydrazide for complex (2), have been synthesized and fully characterized on the basis of elemental analysis, FT-IR, molar conductivity, and electronic spectra. Structures of the complexes have been accomplished by single crystal X-ray diffraction. The complexes have distorted octahedral structures in which the aroylhydrazones behave as binegative ligands. It is also revealed from the crystal structures that the Mo(VI) center adopts NO₅ donor environment, and the octahedral coordination is furnished by two oxido groups and oxygen atoms of methanol or deprotonated methanol molecules. The catalytic properties were investigated for epoxidation of cyclooctene using aqueous tert-butyl hydroperoxide as the oxidant.