A combined experimental and theoretical study of covalent vs noncovalent dimer formation in vanadium(V) complexes with Schiff base ligands

Abstract

This manuscript reports the synthesis, spectroscopic and X-ray characterization of three new vanadium(V) complexes, namely [VO2L1] (1), (μ-O)2[V(O)(L2)2]·2CH3CN (2) and (μ-O)2[V(O)(L3)2]·CH3CN (3) [HL1 (2-ethoxy-6-((quinolin-8-ylimino)methyl)phenol), HL2 (2-(1-(2-(methylamino)ethylimino)propyl)phenol) and HL3 (2-(1-(2-(ethylamino)ethylimino)propyl)phenol)]. Complex 1 is a mononuclear dioxovanadium(V) system containing a five coordinated metal center, whilst complexes 2 and 3 are centrosymmetric dinuclear systems with two [(L)V = O] moieties [(L2)- for 2 and (L3)- for 3], which are linked together through asymmetrically bridging oxygen atoms. DFT calculations have been used to rationalize the different behavior of complex 1, that is related to the lack of strong H-bond donors and strong ability to self-assemble via electrostatically enhanced π-stacking interactions. Moreover, the strength of π–π and CH–π interactions has been evaluated and the interactions have been characterized by several computational tools like MEP, QTAIM and NCI Plot.