Inorganic−Organic Hybrid Materials Containing Porous Frameworks: Synthesis, Characterization, and Magnetic Properties of the Open Framework Solids [{Co(4,4‘-Bipy)}V2O6] and [{Co2(4,4‘-Bipy)3(H2O)2}V4O12]·2H2O

Abstract

Synthesis of two novel porous framework hybrid materials, [Co(4,4‘-bipy)V2O6] (1) and [{Co2(4,4‘-bipy)3(H2O)2}V4O12]·2H2O (2), and their characterization by infrared spectroscopy, thermogravimetry, elemental analysis, manganometric titration, surface area measurement, bond valence sum calculations, temperature-dependent magnetic susceptibility measurement, and single-crystal X-ray structure analyses is described. Both compounds exhibit remarkable thermal stability. The three-dimensional structures of 1 and 2 are composed of fused {VO4} motifs linked by {Co(4,4‘-bipy)} coordination polymers. The structure of 1 is comprised of {CoO3N2} trigonal bipyramids, linked in two dimensions by corner-sharing {VO4} tetrahedra and in the third dimension by the 4,4‘-bipyridine ligands. In the bimetallic layers, the cobalt centers are bridged alternately by {VO4} and {V2O7} units, generating alternating eight-membered {Co2V2O4} and twelve-membered {Co2V4O6} rings. The crystal structure of 2 consists of a novel three-dimensional network containing two types of octahedral Co2+ ions linked by a {V2O7} group. The cobalt centers in 2 are linked in three dimensions by bridging 4,4‘-bipyridine ligands. The structure contains rather large channels parallel to the c-axis. A disordered water molecule of crystallization is present in the channels. Crystal data for C10H8N2O6CoV2, 1: triclinic space group P1̄ (No. 2), a = 8.1517(4) Å, b = 8.5794(4) Å, c = 10.1233(5) Å, α = 87.0170(10)°, β = 75.9610(10)°, γ = 75.1740(10)°, V = 663.94(6) Å3, Z = 2, Dcalcd = 2.066 Mg·m-3, R1 = 0.0252 (all data), wR2 = 0.0669. Crystal data for C15H16N3O8CoV2, 2: monoclinic space group C2/c (No. 15), a = 30.4457(13) Å, b = 11.3540(5) Å, c = 11.5836(5) Å, β = 106.5390(10)°, V = 3838.6(3) Å3, Z = 8, Dcalcd = 1.824 Mg·m-3, final R1 = 0.0447 (all data), wR2 = 0.1259.