Solid-state coordination chemistry: Structural influences of copper-phenanthroline subunits on oxovanadium organophosphonate phases. Hydrothermal synthesis and structural characterization of the two-dimensional materials [Cu(phen)(VO)(O₃PCH₂PO₃)(H₂O)]

The hydrothermal reactions of CuCl₂·2H₂O, Na₃VO₄, 1,10-phenanthroline, and the appropriate organodiphosphonate ligand yield [Cu(phen)(VO)(O₃PCH₂PO₃)(H₂O)] (1), [{Cu(phen)}₂(V₂O₅) (O₃PCH₂CH₂PO₃)] (2), [{Cu(phen)}₂(V₃O₅) (O₃PCH₂CH₂CH₂ PO₃)₂ (H₂O)] (3), and [{Cu(phen)}₂(V₃O₅) (O₃PCH₂PO₃)₂(H₂O)] (4). Compounds 1-3 exhibit two-dimensional structures. The structures exhibit distinct vanadium building blocks: square pyramidal, mononuclear V(IV) sites in 1, a binuclear unit of corner-sharing V(V) tetrahedra in 2, and a trinuclear unit of corner-sharing V(V) square pyramids and a V(IV) octahedron in 3. The network structures of 1 and 2 are constructed from one-dimensional oxovanadium-diphosphonate chains linked by Cu(II) square pyramids into two-dimensional layers. In contrast, compound 3 exhibits a two-dimensional oxovanadium-organodiphosphonate network, with Cu(II) sites decorating the surfaces. Compound 4 is unique in exhibiting a framework structure, which may be described as a three-dimensional oxovanadium-organodiphosphonate substructure with {Cu(phen)}²⁺ subunits covalently attached to the surface of channels running parallel to the a-axis. The magnetic properties of 1-4 are also correlated to the structural characteristics. The magnetic behavior of 2 is thus dominated by antiferromagnetic interactions. The magnetic behavior of 1 and 4 is consistent with the presence of two distinct paramagnetic metal ions, Cu(II) and V(IV). In contrast, 3 does not exhibit ferrimagnetic behavior, but rather weak antiferromagnetic coupling. Crystal data: 1, C₁₃H₁₀N₂CuP₂VO₈, monoclinic P2₁/c, a = 9.0656(5) Å, b = 8.6584(5) Å, c = 20.934(1) Å, β = 97.306(1)°, Z = 4; 2, C₂₆H₂₀N₄Cu₂ P₂V₂O₁₁, triclinic P1, a = 10.6096(5) Å, b = 11.6951(5) Å, c = 13.1796(6) Å, α = 71.369(1)°, β= 70.790(1)°, γ = 80.738(1)°, Z = 2; 3, C₃₀H₂₈N₄Cu₂ P₄V₃O₁₈, triclinic P1, α = 9.4356(6) Å, b = 10.6556(6) Å, c = 11.0354(7) Å, α = 118.187(1)°, β= 91.416(1)°, γ = 107.821(1)°, Z = 1; 4, C₂₆H₂₀N₄ Cu₂P₄V₃O₁₈, monoclinic, P2₁/c a = 8.3947(3) Å, b = 16.8401(7) Å, c = 11.9144(5) Å, β = 93.903(1)°, Z = 2.