Dioxo and oxo-peroxo molybdenum(VI) complexes bearing salicylidene 2-picoloyl hydrazone: Structures and catalytic performances

چکیده مقاله

Molybdenum complexes bearing a salicylidene 2-picoloyl hydrazone ligand have been synthesized and characterized. The salicylidene 2-picoloyl hydrazone ligand (H2sal-phz) was prepared by reaction of picoloyl hydrazine with salicylaldehyde. Reaction of H₂sal-phz with MoO₂(acac) ₂ generates the dioxo molybdenum complex MoO₂(sal-phz) (CH₃OH). Treatment of MoO₃ in the presence of H ₂O₂ with H₂sal-phz produces the oxo-peroxo molybdenum(VI) complex MoO(O₂)(sal-phz)(CH₃OH). The new compounds were characterized by ¹H NMR and IR spectroscopies, and elemental analysis. The complexes were also characterized by single crystal X-ray diffraction crystallography. The complexes were evaluated for epoxidation catalysis with tert-butyl hydroperoxide (tert-BuOOH). The MoO ₂(sal-phz)(CH₃OH) complex exhibited high catalytic activity for the epoxidation of olefins, whereas the peroxo analogue is inert to reaction with olefins, thus ruling out the peroxide compound as the intermediate responsible in the [MoO₂(sal-phz)(CH₃OH)]- catalyzed epoxidation with tert-BuOOH. © 2013 Elsevier Ltd. All rights reserved.