Chiral oxidovanadium(V) complexes with tridentate Schiff bases derived from S(+)-2-amino-1-propanol: Synthesis, structure, characterization and catalytic activity

摘要

A series of vanadium(V) complexes with chiral tridentate Schiff base ligands, obtained by a single condensation of S(+)-2-amino-1-propanol with salicylaldehyde and its derivatives, were prepared. The complexes were characterized by elemental analysis and by their IR, CD, UV-Vis, 1D (~1H, ~(51)V) and 2D (COSY, gHSQC) NMR spectra. The X-ray analysis of μ-oxido-bis({S(+)-2-[(1-oxidopropyl)iminomethyl]-4- nitrophenolato-κ ~3N,O,O′}oxidovanadium(V)), V _2O _3(C _(10)H _(10)N _2O 4) _2, 7, revealed oxido-bridged dinuclear structure with, unexpectedly, two five-coordinate square-pyramidal geometries about metal atoms. The two O-bonded oxidovanadium units are in the twist-angular configuration with the V ~V-O-V ~V angle of 107.05(11)° and V-O distances of 1.794(2) and 1.826(2) ?. The vanadium(V) complexes have ability to catalyze the oxidation of sulfides [PhSR (R = Me, Bz)] in good yields and enantiomeric excesses, utilizing aqueous 30% hydrogen peroxide or cumene hydroperoxide (CHP) as oxidant.