Co-ordination of the chiral N, O-ligand 2-[(1S, 2S, 5R)(-)-menthol]-pyridine to molybdenum(VI) and vanadium(IV) oxo complexes Crystal structures of [MoO_2{2-(-)-menthol-pyridine}_2] and [VO{2-(-)-menthol-pyridine}_2]

摘要

Reaction of the chiral 1-pyridin-2-yl-menthol ligand (1) with [VO(acac)_2] and [MoO_2(acac)_2] results in the formation of the metal-oxo complexes [VO(N-O)_2] (2) and [MoO_2(N-O)_2] (3), where N-O = 2-[(-)-menthol]-pyridine. The molecular structures of (2) and (3) have been determined by single-crystal X-ray diffraction, which revealed the expected square-pyramidal geometry for (2) with the pyridine ring nitrogens mutually trans, and the expected slightly distorted octahedral arrangement of (3) with cis di-oxo ligands. Both metal-oxo compounds (2) and (3) have demonstrated the ability to catalyse the asymmetric oxidation of prochiral olefins and sulfides with H_2O_2 or tBuOOH as the oxidant.