X-ray structure analysis, electronic and vibrational circular dichroism of chiral-at-metal dioxidovanadium(V) complexes with amino acids derived Schiff base ligands

摘要

Five new chiral dioxidovanadium Schiff base complexes derived from L-valine, L-leucine, L-histidine, L-threonine and D-threonine were synthesized and characterized by elemental analysis, ~1H and ~(51)V NMR and IR spectra. The absolute configurations of the complexes were determined by X-ray single crystal analysis in solid state and by electronic and vibrational circular dichroism in CH_3CN solution. The L-threoninato complex, which contains two stereogenic centers in the amino acid site, does not show epimerization of the amino acid, in contrast with the analogical isoleucine-derived complexes reported recently. Conglomerate crystallization was observed in racemic DL-valine- and DL-threonine-derived complexes.