The First Neutral Dinuclear Vanadium Complex Comprising VO and VO₂ Cores: Synthesis, Structure, Electrochemical Properties, and Catalytic Activity

Abstract

Abstract A neutral dinuclear vanadium complex containing both oxido and dioxidovanadium cores with hydrazone based ligand, [VO(OCH 3 )(CH 3 OH)(HL)VO 2 ] ( 1 ) {H 4 L = bis[( E )‐ N ′‐(5‐bromo‐2‐hydroxybenzylidene)]‐carbohydrazide}, was synthesized and fully characterized by X‐ray crystallography and spectroscopic methods (IR, UV/Vis, NMR). The ligand acts as a trinegative hexadentate N 3 O 3 donor ligand to form a dinuclear complex and during the reaction V 4+ is oxidized to V 5+ . The coordination polyhedra are a VO 5 N distorted octahedron for the mono‐oxidovanadium core and a VO 3 N 2 trigonal bipyramid for the dioxidovanadium core. The results of catalytic reactions indicate that 1 is a highly active catalyst in the clean epoxidation reaction of cis ‐cyclooctene using aqueous hydrogen peroxide in acetonitrile. Cyclic voltammetric experiments of 1 in DMSO reveal two quasi‐reversible peaks due to the VO 3+ –VO 2+ and VO 2 + –VO 2 couples.