Introducing organosilicone source into the synthetic system of polyoxovanadates: two novel {V15Si6O48}-based extended chains

Abstract

Two novel extended chains based on rare {V^IV₁₅Si₆O₄₈} have been prepared under hydrothermal conditions by introducing an organosilicone source into the synthetic system of the polyoxovanadates. Single-crystal X-ray diffraction analyses show that the neighboring {V^IV₁₅Si₆O₄₈} clusters are linked by a pair of V^VO₂ fragments via the coordination bonds of (Si–)O–V–O(–Si) to give rise to a zig-zag chain in compound 1, which is the first example of V(IV,V) mixed valence states successfully synthesized in {V₁₅Si₆O₄₈}-containing POMs. While in 2 the linkages are changed to [Co(pdn)₂(H₂O)]²⁺ (pdn = 1,3-propanediamine) cations instead of {V^VO₂} fragments, to generate another comparable 1-D infinite chain, which demonstrates the first organic-inorganic vanadosilicon hybrid linked by a second transition-metal complex. The possible hydrolysis mechanism of tetraethyl orthosilicate as the Si source is postulated to afford a feasible protocol to synthesize a new type of vanadosilicate cluster. The magnetic properties of the two compounds have also been investigated.