Hydrothermal syntheses of materials constructed from vanadium oxide and secondary metal-tetrapyridylpyrazine subunits. Structural consequences of the identity of the secondary metal

Hydrothermal reactions of V₂O₅, tetra-2- pyridylpyrazine (tpyprz) and an appropriate M(II) starting material yield a series of oxides of general composition [{M_x(tpyprz)} _yV₄O₁₂] [x=1, y=2, M=Co(II), Ni(II); x=2, y=2, M=Cu(I); x=2, y=1, M=Zn(II)]. The Co(II) and Ni(II) analogues (1 and 2) are isostructural and consist of one-dimensional ribbons constructed from {V ₄O₁₂}^4- clusters linked through {M(tpyprz)}₂⁴⁺ binuclear units of edge sharing {MO ₃N₃} octahedra. In contrast, the structure of [{Cu ₂(tpyprz)}₂V₄O₁₂] (3) is two-dimensional and constructed of {Cu₂(tpyprz)}_n ²ⁿ⁺ chains linked in the second dimension through the {V ₄O₁₂}^4- clusters. The structure of [{Zn ₂(tpyprz)V₄O₁₂] (4) is also two-dimensional but may be described as {Zn₂V₄O₁₂} chains interconnected through the binucleating tpyprz ligands. The roles of the coordination preferences of the secondary metal cations as well as the nature of the organic components are discussed.