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(Ill) diphosphonate, Fe-III (H2O) (HO3P(CH2)(2)PO3) 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 R-1 = 0.0380. The structure consists of inorganic sheets pillared by the 1,2-ethylenediphosphonate groups. The sheets are composed of Fe(H2O)O-5 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).