Ionothermal synthesis and crystal structure of a new layered nickel(II) diphosphate, DRM-1

A new layered ammonium nickel(II) diphosphate, (NH4)2[Ni3(P2O7)2(H2O)2], has been synthesized ionothermally in the ionic liquid 1-butyl-3-methyl imidazolium bromide and characterized by powder X-ray diffraction, elemental analysis, scaning electron microscopy, thermogravimetry etc. The results of the characterization show that the crystal adopts the monoclinic space group P21/a with the lattice constants a = 9.23529(2) Å, b = 7.98489(2) Å, c = 9.40772(2) Å, β = 100.2608(2)° and Z = 2. Its structure consists of chains of cis- and trans-edge-sharing [NiO6]-octahedra linked via [P2O7] units to form layers of [Ni3(P2O7)2(H2O)2]2− in the ab plane. Adjacent layers are separated in the c-direction by ammonium ions.