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

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 51V 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 CH3CN 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.

Graphical abstractThe absolute configuration on the vanadium atom in five new chiral dioxidovanadium Schiff base complexes derived from l-valine, l-leucine, l-histidine, l-threonine and d-threonine is discussed by the means of X-ray single crystal analysis, electronic and vibrational circular dichroism.Figure optionsDownload full-size imageDownload as PowerPoint slide