Pillared Layered Structures Based upon M(III) Ethylene Diphosphonates: The Synthesis and Crystal Structures of MIII(H2O)(HO3P(CH2)2PO3) (M = Fe, Al, Ga)

A three-dimensional iron(III) diphosphonate, FeIII(H2O)(HO3P(CH2)2PO3), I, has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group Pbca (no. 61) where a = 9.739(5) (angstrom), b = 9.498(5) (angstrom), c = 15.940(8) (angstrom), V = 1474.4(1) (angstrom)^3, Z = 8, and R1 = 0.0380. The structure consists of inorganic sheets pillared by the 1,2-ethylenediphosphonate groups. The sheets are composed of Fe(H2O)O5 octahedra connected through PO3C tetrahedra. The corresponding isostructural aluminum (II) and gallium (III) compounds were also synthesized and indexed: II, a = 9.534(1) (angstrom), b = 9.255(2) (angstrom), c = 15.724(1) (angstrom), V = 1387.5(1) (angstrom)3; III, a = 9.670(1) (angstrom), b = 9.357(2) (angstrom), c = 15.862(4) (angstrom), V = 1435.4(1) (angstrom)^3.