Synthesis and molecular structural studies of racemic chiral-at-vanadium(v) complexes using an unsymmetric achiral phenolic bidentate ligand

Abstract

Mononuclear oxovanadium(V) complexes [V(O)XL (1: X = Ot-Bu, 2: X = Cl)] [H₂L: 2,2′-methylene bis(4,6-di-tert-butylphenol)(4′-tert-butyl-6′-(1-adamantyl)phenol)] directed towards asymmetric catalysis have been synthesised as racemic compounds using an unsymmetric and achiral phenolic bidentate ligand (H₂L), and NMR and UV-vis absorption spectroscopies, single-crystal X-ray diffraction, and IR spectroscopy revealed their racemic chiral-at-vanadium structures in solution and in the crystal. In addition, theoretical calculations revealed that the HOMO–LUMO energy gap is smaller for unsymmetric ligands, which promotes d-orbital splitting of the metal centre.