Non-covalent interactions in hexanuclear polyoxidometalates [VIV6B20O50H8]8−. An experimental and theoretical approach

A complete study of the optical and magnetic properties three new {V6-type} polyoxidometalates (NH3CH2CH2CH2NH3)4{V6B20O50H8}·4H2O 1, K2(NH3CH2CH2NH3)2.5(NH3CH2CH2NH2){V6B20O50H8}·2H2O 2, K2(NH3CH2CH2CH2NH3)2(H3O)2{V6B20O50H8}·8H2O 3 is presented. Using TD-DFT calculations, assignment experimental UV–Visible spectra was established with four absorption bands: a higher in energy assigned to metal-to-metal charge transfer remaining associated principally d-d transitions, demonstrating that {V6IVO18}12− ring principal chromophore for these systems surrounding packing does not have an influence on it. On other hand, differences observed are caused by non-covalent interactions between potassium ions some oxygen atoms VIV coordination spheres, thus modifying VIV-VIV exchange coupling. This effect demonstrated using simplified binuclear DFT model predicts antiferromagnetic coupling when K cations become closer bridge link centres ring.