Exploration of Br···O halogen bonding interactions in dinuclear vanadium(V) complexes with schiff base ligands

Abstract

An oxo-bridged dinuclear vanadium(V) complex, (µ-O)2[V(O)(L)]2, [where HL = 2-((2-(methylamino)ethylimino)methyl)-4-bromo-6-methoxyphenol] has been synthesized and characterized by elemental and spectral analysis. Structure of the complex has been determined by single crystal X-ray diffraction study. The complex generates an infinite 1D chain governed by Br···O halogen bond involving the oxygen atoms of the VO2+ unit as electron donor and the σ-hole at the halogen as electron acceptor. The molecular electrostatic potential (MEP) surface of the complex has been computed, which indicates that the most electron rich part corresponds to the oxygen atoms of the VO2+ unit and the existence of a σ-hole (+9.4 kcal/mol) around Br atom, and therefore justifies the formation of a directional halogen bonding interaction. The interaction in the complex has also been characterized energetically by using the Bader´s quantum theory of "atoms in molecules" (QTAIM). The contribution of the halogen bond is found to be ∼ ?6.3 kcal/mol, which is in the range of typical halogen bonds. The results have been compared with the energies of Br···O halogen bond interactions in a structurally similar oxo-bridged dinuclear vanadium(V) complex.