Hydrothermal Syntheses and Structural Characterizations of Organic-Inorganic Hybrid Materials of the M(II)-Ligand/Vanadium Oxide System (M(II)=Cu(II) and Zn(II); Ligand=2,2'-Bipyridine and 2,2':6',2'-Terpyridine

摘要

Investigation into the incorporation of complex transition metal-organic units into vanadium oxide structures has resulted in the preparation of several novel composite materials. Hydrothermal reactions of V_2O_5,2,2'-bipyridine, an appropriate Zn or Cu starting material, and H_2O under a variety of conditions yielded the organic-inorganic hybrid materials [{Zn(2,2'-bpy)}_2V_4O_12](1) and [Cu(2,2'-bpy)V_4O_10.5](2). Blocking an additional coordination site on the secondary metal center by using a tridentate organonitrogen ligand, 2,2':6',2"-terpyridine in place of 2,2'-bipyridine, allowed the isolation of [Cu(terpy)V_2O_6] (3) and [{Zn(terpy)}_2V_6O_17] (4). The structure of 1 is a two-dimensional zinc vanadate layer, composed of rings containing four corner-sharing {CO_4} vanadium(V) tetrahedra linked through six zinc square pyramids, with the 2,2'-bipyridine groups attached to the zinc centers and directed above and below the plane of the layer. In contrast to 1, the layer of 2 is based on a two-dimensional vanadium oxide substructure composed of vanadium(IV) square pyramids and vanadium(V)tetrahedra with copper square pyramids attached through corner-sharing interactions with vanadium tetrahedra such that the bipyridine ligands attached to the copper sites form staggered stacks above and below the plane of the layer. Compound 3 consists of one-dimensional vanadium oxide chains of corner-sharing tetrahedra linked through copper-terpyridine units into a two-dimensional bimetallic oxide of composition {CuV_2O_6}, while the layer structure of 4 contains more complex one-dimensional vanadium oxide chains composed of fused rings of six corner-sharing vanadium oxide tetrahedra which are linked into a layer through {Zn(terpy)}~(2+) units.