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)

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 V2O5, 2,2‘-bipyridine,
an appropriate Zn or Cu starting material, and H2O under a variety of conditions yielded the organic−inorganic
hybrid materials [{Zn(2,2‘-bpy)}2V4O12] (1) and [Cu(2,2‘-bpy)V4O10.5] (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)V2O6] (3) and [{Zn(terpy)}2V6O17] (4). The structure of 1 is
a two-dimensional zinc vanadate layer, composed of rings containing four corner-sharing {VO4} 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 {CuV2O6}, 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.