The vanadyl or oxovanadium(IV) cation, VO2+,[1] is a functional group that is common in the coordination chemistry of vanadium. Complexes containing this functional group are characteristically blue and paramagnetic. A triple bond is proposed to exist between the V4+ and O2− centers.[2] The description of the bonding in the vanadyl ion was central to the development of modern ligand-field theory.[3]