Synthesis, crystal structures, and catalytic oxidation of olefins of dioxomolybdenum(VI) complexes with aroylhydrazone ligands

Abstract

Two Mo(VI) aroylhydrazone complexes, cis-[MoO₂(L¹)(CH₃OH)] (I) and cis-[MoO₂(L²)(CH₃OH)] (II), derived from 2-bromo-N'-(3,5-dibromo-2-hydroxybenzylidene)benzohydrazide (H₂L¹) and 2-bromo-N'-(2-hydroxy-4-methoxybenzylidene)benzohydrazide (H₂L²), respectively, are reported. The complexes were characterized by elemental analyses, infrared and electronic spectroscopy, and single crystal structure analysis (CIF files CCDC nos. 1443679 (I) and 1443678 (II)). The Mo atoms are coordinated by two cis terminal oxygen, ONO from the aroylhydrazone ligand, and methanol oxygen. Complex I crystallized as monoclinic space group P2₁/_c with unit cell dimensions a = 8.075(2), b = 13.905(1), c = 16.448(1) Å, β = 91.282(2)°, V = 1846.5(4) ų, Z = 4, R₁ = 0.0859, wR₂ = 0.2066. Complex II crystallized as triclinic space group P\(\overline 1 \), with unit cell dimensions a = 8.0824(6), b = 10.5919(8), c = 10.7697(8), α = 96.432(2)°, β = 97.438(2)°, γ = 103.119(2)°, V = 880.8(1) ų, Z = 2, R₁ = 0.0271, wR₂ = 0.0571. The complexes were tested as catalyst for the oxidation of olefins and showed effective activity.