Synthesis, Characterization, and Crystal Structures of Dioxomolybdenum(VI) Complexes Derived from Similar Tridentate Hydrazone Compounds with Catalytic Property

Abstract

Two hydrazone compounds 2-chloro-N'-(2-hydroxy-4-methoxybenzylidene)benzohydrazide (H₂L¹) and N'-(2-hydroxy-4-methoxybenzylidene)-3-methylbenzohydrazide (H₂L²) were prepared and characterized by IR, UV-Vis and ¹H NMR spectra. Based on the hydrazone compounds, two new structurally similar dioxomolybdenum(VI) complexes, [MoO₂L¹(CH₃OH)] (I) and [MoO₂L²(CH₃OH)] (II), were prepared and characterized by IR and UV-Vis spectra, and single crystal X-ray diffraction (CIF files nos. 1566491 (I) and 1566492 (II)). Complex I crystallizes as the triclinic space group P\(\bar {1}\) with unit cell dimensions a = 8.0750(5), b = 10.5223(7), c = 10.8110(7) Å, α = 96.975(2)°, β = 97.909(2)°, γ = 104.497(2)°, V = 869.2(1) ų, Z = 2, R₁ = 0.0323, wR₂ = 0.0620, GOOF = 1.089. Complex II crystallizes as the monoclinic space group P2₁/n with unit cell dimensions a = 11.680(1), b = 10.496(2), c = 14.879(2) Å, β = 98.862(2)°, V = 1802.2(4) ų, Z = 4, R₁ = 0.0270, wR₂ = 0.0675, GOOF = 1.111. X-ray analysis indicates that the complexes are mononuclear dioxomolybdenum(VI) species with the Mo atoms in octahedral coordination. The complexes were studied for their catalytic oxidation property on some olefins with tert-butyl hydrogen peroxide as oxidant.