Structural study of cadmium hydroxide sulfates. VI. The layer structure ofCd4SO4(OH)(6).1.5H(2)O studied from X-ray powder and single-crystal diffraction data

The crystal structure of the layered cadmium hydroxide sulfate Cd4SO4(OH)(6 ).1.5H(2)O has been solved from X-ray powder diffraction data. The compound crystallizes with hexagonal symmetry, a = 9.145(1) Angstrom, c = 15.099(3) Angstrom, V = 1093.5 Angstrom (3), Z = 4, space group P6(3). Due to the un usual environment of one cadmium atom and to the fact that a suitable thin tabular crystal could be found later, a single-crystal X-ray diffraction ex periment was also carried out. In both cases the structure was solved apply ing direct-methods. The refinements converged to the residual factors R-wp = 0.152 and R-F = 0.059 from the powder data and R-1 = 0.058 and wR = 0.165 for the single crystal data case. The structure is built from brucite-type layers based on CdO6 octahedra, in which one-seventh of the octahedral sit es are empty. Directly above and below these empty sites, two additional oc tahedrically coordinated Cd atoms are located. The crystal chemistry of the cadmium hydroxide sulfate family is discussed. (C) 2001 International Cent re for Diffraction Data.