Synthesis and characterization of an organic-inorganic hybrid crystal: 2[Co(en)3](V4O13)·4H2O.

Organic-inorganic hybrid crystals have diverse functionalities, for example in energy storage and luminescence, due to their versatile structures. The synthesis and structural characterization of a new cobalt-vanadium-containing compound, 2[Co(en)₃]³⁺(V₄O₁₃)^6-·4H₂O (1) is presented. The crystal structure of 1, consisting of [Co(en)₃]³⁺ complexes and chains of corner-sharing (VO₄) tetrahedra, was solved by single-crystal X-ray diffraction in the centrosymmetric space group P1. Phase purity of the bulk material was confirmed by infrared spectroscopy, scanning electron microscopy, elemental analysis and powder X-ray diffraction. The volume expansion of 1 was found to be close to 1% in the reported temperature range from 100 to 300 K, with a volume thermal expansion coefficient of 56 (2) × 10^-6 K^-1. The electronic band gap of 1 is 2.30 (1) eV, and magnetic susceptibility measurements showed that the compound exhibits a weak paramagnetic response down to 1.8 K, probably due to minor Co^II impurities (<1%) on the Co^III site.