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Synthesis and Catalytic Properties of Molybdenum(VI) Complexes with tridentate Schiff base ligands

Mononuclear [MoO2(L)(D)], and dinuclear [MoO2(L)]2 dioxomolybdenum(VI) complexes have been prepared by the reaction of tridentate Schiff-base ligands L with [MoO2(acac)2]. The Schiff-base ligands have been synthesized from salicylaldehyde (I-III), 2- hydroxy-3-methoxybenzaldehyde (IV-VI) and 2- hydroxy-1-naphthaldehyde (VII-VIII) with 2-amino- 4-methyphenol, 2-amino-5-methylphenol and 2- aminophenol. All prepared complexes consist of cis-MoO22+ core coordinated by dianionic tridentate Schiff base ligand ligand through two deprotonated hydroxyl groups and one imino nitrogen atom. The usual octahedral coordination around the molybdenum atoms is completed by the neutral ligand D (methanol). All compounds were characterized by IR spectroscopy, TGA measurments and powder diffraction. In addition, crystal and molecular structure was determined by single X-ray diffraction. Molybdenum(VI) compounds were used as (pre)catalysts for olefin epoxidation with TBHP under solvent free conditions with 0.5% Mo loading versus olefin. Used olefins were: cis-cyclooctene, cyclohexene and limonene.

epoxidation; homogeneus catalysis; molybdenum; Schiff base ligands; solvent-free conditions; olefins

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