A new iron (II) hydroxyphosphate containing linear ammonium chloride chains : (NH4Cl)Fe14(OH)6(PO4)6(HPO4)2

A new iron (II) hydroxyphosphate, (NH4Cl)Fe14(OH)6(PO4)6(HPO4)2, has been synthesized using hydrothermal technique. It crystallizes in the monoclinic C2/m space group with a = 16.573(5) Å, b = 6.309(1) Å, c = 16.623(4) Å and β = 115.434(17)° (V = 1569.7(4) Å3, Z = 2). The unique structure of this compound is built up from phosphate and hydroxyphosphate tetrahedra sharing apices and edges with three different types of iron coordination polyhedra : octahedra, trigonal bipyramids and tetrahedra. The resulting 3D host lattice [Fe14(OH)6(PO4)6(HPO4)2]∞ is electrically neutral and forms large eight-sided tunnels containing linear chains of ammonium chloride.

Projection of the 3D structure of (NH4Cl)Fe14(OH)6(PO4)6(HPO4)2 along [010], showing the different types of iron polyhedra (blue polyhedra) which connexions delimit octagonal tunnels containing NH4+ and Cl− ions aligned along b.Figure optionsDownload as PowerPoint slide