Synthesis and characterization of novel V/O/SO4 chains incorporating 2,2′-bipyridine ligands:: Crystal structure of [V2O2(OH)2(SO4)(2,2′-bpy)2]

The hydrothermal reaction of a mixture of vanadyl acetylacetonate (VO(acac)(2)), Na2SO4, 2, 2'-bipyridine (2, 2'-bpy), and H2O for 48 h at 160 degrees C gives brown crystals of [V2O2(OH)(2)(SO4)(2, 2'-bpy)(2)] (1) in 70% yield. The structure of 1 consists of ribbons constructed from the infinite inorganic chains, [-{V2O2(OH)(2)}-mu(2)-SO4{V2O2-(OH)(2)}-SO4](infinity), incorporating organic (2, 2'-bipyridine) ligands. The inorganic chains are composed of the pairs of edge-sharing octahedra joined by {SO4} tetrahedra through octahedral-tetrahedral corner sharing. The octahedral geometry around each vanadium(IV) ion is defined by {VO2(OH)(2)N-2} with each V-IV center coordinated to a terminal oxo group, two mu(2)-OH groups, two nitrogen donor atoms from a chelating 2, 2'-bipyridine ligand, and an oxygen donor atom from a mu(2)-SO42- ligand. Crystal data for 1: monoclinic space group P2(1)/n (No. 14), a = 11.7937(2) Angstrom, b = 12.1161(3) Angstrom, c = 15.5763(2) Angstrom, beta = 93.750(2)degrees, Z = 4. 1 constitutes the first example of a fully reduced vanadosulfate (V/O/SO4) based solid incorporating both the organic and inorganic ligands. The novel solid exhibits Curie-Weiss paramagnetism at high temperature (T > 140 K) and short-range antiferromagnetic coupling between the V-IV centers at lower temperature.