Inorganic-organic hybrid materials:: Hydrothermal synthesis and characterization of the metal diphosphonates M2(O3PCH2C6H4CH2PO3)•2H2O(M = Mn, Ni, Cd)

The three isostructural transition metal diphosphonates M-2(O3PCH2C6H4CH2PO3) . 2H(2)O (M = Mn, Ni, Cd) were hydrothermally synthesized using p-xylenediphosphonic acid and the corresponding metal salts. The structures were refined in the orthorhombic space group Pca2(1) from X-ray powder diffraction data: Mn-2(O3PCH2C6H4CH2PO3) . 2H(2)O (1): a = 983.71(7), b = 582.72(4), c 2173.5(2) pm, V = 1245.8(1) 10(6) pm, Z = 4, wR(P) = 0.079, R-P = 0.062, R-F = 0.081; Ni-2(O3PCH2C6H4CH2PO3) . 2H(2)O (2): a = 951.18(3), b = 562.31(2), c = 2178.47(6) pm, V = 1165.2(1) 10(6) pm, Z = 4, wR(P) = 0.072, R-P = 0.054, R-F = 0.095; Cd-2(O3PCH2C6H4CH2PO3) . 2H(2)O (3): a = 1005.19(3), b = 594-37(2), c 2186.08(8), V = 1304.3(1) 10(6) pm, Z = 4, wR(P) = 0.067, R-P 0.052, R-F = 0.059. The structures are built up from corner-linked [MO6] polyhedra (M = Mn, Ni, Cd) forming inorganic metal oxide layers. These layers are linked by the organic diphosphonic acids acting as pillars. Magnetization measurements of 1 confirm the presence of divalent ions and indicate antiferromagnetic ordering at low temperatures. Thermogravimetric as well as IR spectroscopic studies are also presented. (C) 2002 Elsevier Science (USA).