Synthesis and characterization of organically templated metal arsenates with a layer structure: [NH3(CH2)(3)NH3](0.5)[M(OH)AsO4] (M = Ca, Fe)

Two organically templated metal arsenates, [NH3(CH2)(3) NH3](0.5)[M(OH)AsO4 ] (M = Ga, Fe), have been synthesized under hydrothermal conditions and cha racterized by single-crystal X-ray diffraction and Ga-71 NMR spectroscopy. The two compounds are isostructural and crystallize in the orthorhombic spa ce group Fdd2 (No, 43) with a = 9.5584(7) Angstrom, b = 41.593(3) Angstrom, c = 5.6438(4) Angstrom, V = 2243.8(3) Angstrom (3), and Z = 16 with R-1 = 0.0302 for the Ga compound, and a = 9.7301 (2) Angstrom, b = 41.5035(2) Ang strom, c = 5.7411(1) Angstrom, V = 2318.45(8) Angstrom (3), and Z = 16 with R-1 = 0.0228 for the Fe compound. The structure consists of two-dimensiona l anionic sheets of metal arsenate in the ac plane with charge-compensating propanediammonium cations between the sheets, The sheets are constructed f rom infinite chains of cis-corner-sharing MO6 octahedra, which are joined b y arsenate ligands, This work is one of the few studies concerning organica lly templated metal arsenates. (C) 2000 Academic Press.