Solid state coordination chemistry: secondary metal–ligand influences on the structures of vanadium oxides. Hydrothermal syntheses and structures of [Zn(tpytrz)2V2O6], [Zn3(tpytrz)2(H2O)2V6O18]·6H2O and [Cu3(tpytrz)2(H2O)2V8O23]·3H2O (tpytrz = 2,4,6-tri(4-pyridyl)-1,3,5-triazine)

Abstract

The hydrothermal reactions of Zn(SO₄)·5H₂O, V₂O₅ and 2,4,6-tri(4-pyridyl)-1,3,5-triazine (tpytrz) yield [Zn(tpytrz)₂V₂O₆] (1) at pH 6.5 and [Zn₃(tpytrz)₃(H₂O)₂V₆O₁₈]·6H₂O (2·6H₂O) at pH 3.5. Substitution of Cu(II) as the secondary metal in the reaction of Cu(SO₄)·5H₂O, V₂O₅ and tpytrz yields [Cu₃(tpytrz)₂(H₂O)₂V₈O₂₃]·3H₂O (3·3H₂O). The structure of 1 consists of a bimetallic oxide layer, decorated on both surfaces by monodentate tpytrz groups. The structure of 2 is three-dimensional and constructed from a 3-D bimetallic oxide framework with the organic subunit entrained within larger channels in the oxide scaffolding. While the structure of 3 is grossly similar to that of 2, the different coordination preferences of Zn(II) and Cu(II) are manifested in the detailed structural features. Thus, while the vanadate substructure of 2 is one-dimensional, that of 3 is two-dimensional. Similarly, 2 exhibits both tetrahedral and octahedral secondary metal sites, while 3 possesses only ‘4 + 2’ axially distorted Cu(II) sites.