Synthesis and Characterization of Novel V/O/SO4Chains Incorporating 2,2‘-Bipyridine Ligands: Crystal Structure of [V2O2(OH)2(SO4)(2,2‘-bpy)2

Abstract

The hydrothermal reaction of a mixture of vanadyl acetylacetonate (VO(acac)(2)), Na(2)SO(4), 2,2'-bipyridine (2,2'-bpy), and H(2)O for 48 h at 160 degrees C gives brown crystals of [V(2)O(2)(OH)(2)(SO(4))(2,2'-bpy)(2)] (1) in 70% yield. The structure of 1 consists of ribbons constructed from the infinite inorganic chains, [-{V(2)O(2)(OH)(2)}-&mgr;(2)-SO(4){V(2)O(2)(OH)(2)}-SO(4)](infinity), incorporating organic (2,2'-bipyridine) ligands. The inorganic chains are composed of the pairs of edge-sharing octahedra joined by {SO(4)} tetrahedra through octahedral-tetrahedral corner sharing. The octahedral geometry around each vanadium(IV) ion is defined by {VO(2)(OH)(2)N(2)} with each V(IV) center coordinated to a terminal oxo group, two &mgr;(2)-OH groups, two nitrogen donor atoms from a chelating 2,2'-bipyridine ligand, and an oxygen donor atom from a &mgr;(2)-SO(4)(2)(-) ligand. Crystal data for 1: monoclinic space group P2(1)/n (No. 14), a = 11.7937(2) Å, b = 12.1161(3) Å, c = 15.5763(2) Å, beta = 93.750(2) degrees, Z = 4. 1 constitutes the first example of a fully reduced vanadosulfate (V/O/SO(4)) 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.