Synthesis and characterization of organically templated metal arsenates with a layer structure: [NH₃(CH₂)₃NH₃]_0.5[M(OH)AsO₄] (M = Ga, 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 characterized by single-crystal X-ray diffraction and ⁷¹Ga NMR spectroscopy. The two compounds are isostructural and crystallize in the orthorhombic space group Fdd2 (No. 43) with a = 9.5584(7) Å, b = 41.593(3) Å, c = 5.6438(4) Å, V = 2243.8(3) ų, and Z = 16 with R₁ = 0.0302 for the Ga compound, and a = 9.7301(2) Å, b = 41.5035(2) Å, c = 5.7411(1) Å, V = 2318.45(8) ų, and Z = 16 with R₁ = 0.0228 for the Fe compound. The structure consists of two-dimensional anionic sheets of metal arsenate in the ac plane with charge-compensating propanediammonium cations between the sheets. The sheets are constructed from infinite chains of cis-corner-sharing MO₆ octahedra, which are joined by arsenate ligands. This work is one of the few studies concerning organically templated metal arsenates. (C) 2000 Academic Press.