Crystal structure of a [(dihydrogen pyrophosphato-K2O,O′) bis(1,10-phenanthroline-N, N′)nickel(II)]2.5-hydrate [Ni(H2P2O7)(C12H8N2)2]·2.5H2O

Coordination nickel pyrophosphate [Ni(H2P2O7)(C12H8N2)2]•2.5H2O (I) is hydrothermally synthesized and characterized by single crystal X-ray diffraction. The title compound crystallizes in the triclinic system, space group P-1, with cell parameters M = 640.07, a = 10.285(2) Å, b = 10.510(3) Å, c = 12.775(3) Å, α = 88.06(2)°, β = 77.87(2)°, γ = 89.26(2)°, V = 1349.2(5) Å3, Z = 2, R1[I > 2σ(I)] = 0.0438, wR2[I > > 2σ(I)] = 0.1244. This compound displays a new structure of ladder-like 2D layers parallel to (010) consisting of [Ni(H2P2O7)(phen)2] entities with the distorted octahedral NiN4O2 coordination geometry arising from two chelating 1,10-phenanthroline ligands and diphosphate [H2P2O7] ligand bridged through π•••π stacking interactions between the neighboring 1,10-phen ligands with interplanar distances of 4.425 Å and 4.525 Å. In the compound, the phen ligands bind in a bidentate fashion to the metal atoms and the ladder-like structure of the compound extends into a three-dimensional supramolecular array via hydrogen bonds (O4–H17…O5) between diphosphate groups, which delimits b axis tunnels where water molecules are located.