| Abstract: | AgCo3H2(AsO4)3 and AgZn3H2(AsO4)3. Preparation and Crystal Structure. Another New Structure Type of an Arsenate AgCo3H2(AsO4)3 ( 1 ) and AgZn3H2(AsO4)3 ( 2 ) were prepared by heating of As2O5, AgNO3, CoSO4 · 7H2O, ZnSO4 · 7H2O, respectively, and water in a sealed tube at 300°C and investigated with X-rays. Both compounds are isotypic and crystallize in the monoclinic space group C2/c with 4 formula units per cell. The lattice parameters are ( 1 ): a = 1215.9(6), b = 1243.8(7), c = 678.2(3) pm, β = 113.16(3)° ( 2 ): a = 1216.9(2), b = 1249.5(3), c = 675.5(1) pm, β = 112.77(1)°. The structure contains chains of edge-shared CoO6 or ZnO6 octahedra, respectively, which are connected by AsO4 tetrahedra and silver oxygen ribbons with square planar coordinated silver forming a framework. Based on the charge balances derived from the geometrical data and the IR spectra the occurence of hydrogen bonds is discussed. |
