Covalent Co–O–V and Sb–N Bonds Enable Polyoxovanadate Charge Control

The formation of [{Co^II(teta)₂}­{Co^II₂(tren)­(teta)₂}­V^IV₁₅Sb^III₆O₄₂(H₂O)]·ca.9H₂O [teta = triethylenetetraamine; tren = tris­(2-aminoethyl)­amine] illustrates a strategy toward reducing the molecular charge of polyoxovanadates, a key challenge in their use as components in single-molecule electronics. Here, a V–O–Co bond to a binuclear Co²⁺-centered complex and a Sb–N bond to the terminal N atom of a teta ligand of a mononuclear Co²⁺ complex allow for full charge compensation of the archetypal molecular magnet [V₁₅Sb₆O₄₂(H₂O)]^6–. Density functional theory based electron localization function analysis demonstrates that the Sb–N bond has an electron density similar to that of a Sb–O bond. Magnetic exchange coupling between the V^IV and Co^II spin centers mediated via the Sb–N bridge is comparably weakly antiferromagnetic.