Mixed-Valence and Neutral Framework Inorganic−Organic Hybrid Materials: Synthesis, Characterization, and Magnetic Properties of [{Co(N(CH)4N)}(V2O5)2] and [{Co(N(CH)4N)}V2O6

Abstract

Two inorganic−organic hybrid materials [{Co(N(CH)4N)}(V2O5)2] (1) and [{Co(N(CH)4N)}V2O6] (2) have been synthesized and characterized by FT-IR spectroscopy, thermogravimetric analysis, elemental analysis, manganometric titration, temperature-dependent magnetic susceptibility measurement, bond valence sum calculations, and single-crystal X-ray diffraction analyses. The neutral framework materials were prepared by the amalgamation of vanadium oxide chains and layers with metal−organoamine coordination polymers. The three-dimensional framework structures of the crystals in 1 and 2 are composed of vanadium oxide layers (1) and chains (2) combined with {Co(N(CH)4N)}2+ motifs that cross-link the reduced vanadium oxide layers (containing mixed-valent vanadium centers) in 1 and oxovanadium chains in 2. Besides crosslinking the metal oxide chains and layers in these materials, cationic metal−pyrazine polymers provide charge balance leading to the neutral framework in these solids. The compounds show good thermal stability. Crystal data for 1 is as follows: C4H4N2O10CoV4, orthorhombic space group Cmcm, a = 14.3071(6), b = 6.9965(3), c = 11.4510(5) Å, V = 1146.24(9) Å3, Z = 4, Dcalcd = 2.913 Mg·m-3, R1 = 0.0385 (all data), wR2 = 0.1019. Crystal data for 2 are as follows: C4H4N2O6CoV2, orthorhombic space group Pnna, a = 10.2524(8), b = 11.5653(9), c = 7.4719(6) Å, V = 885.96(12) Å3, Z = 4, Dcalcd = 2.526 Mg·m-3, R1 = 0.0199 (all data), wR2 = 0.0547.