Amino Alcohol-Derived Reduced Schiff Base VIVO and VV Compounds as Catalysts for Asymmetric Sulfoxidation of Thioanisole with Hydrogen Peroxide

TLDR: Computational and spectroscopic studies were carried out to assist in the understanding of the mechanistic aspects and the reasons behind such marked differences in activity and enantioselectivity of the amino alcohol-derived reduced Schiff base ligands and their related Schiff base variants.

Abstract: We report the synthesis and characterization of several amino alcohol-derived reduced Schiff base ligands (AORSB) and the corresponding VIVO and VV complexes Some of the related Schiff base variants (amino alcohol derived Schiff base = AOSB) were also prepared and characterized With some exceptions, all compounds are formulated as dinuclear compounds {VIVO(L)}2 in the solid state Suitable crystals for X-ray diffraction were obtained for two of the AORSB compounds, as well as a rare X-ray structure of a chiral VIVO compound, which revealed a dinuclear {VIVO(AOSB)}2 structure with a rather short V–V distance of 3053(9) A Electron paramagnetic resonance (EPR), 51V NMR, and density functional theory (DFT) studies were carried out to identify the intervenient species prior to and during catalytic reactions The quantum-chemical DFT calculations were important to determine the more stable isomers in solution, to explain the EPR data, and to assign the 51V NMR chemical shifts The V(AORSB) and V(AOSB) compl