Crystal chemistry of inorganic compounds based on chains of oxocentered tetrahedra - III. Crystal structure of georgbokiite, Cu5O2(SeO3)(2)Cl-2

The monoclinic crystal structure of georgobokiite, a new mineral with the c hemical composition Cu5O2(SeO3)(2)Cl-2 (a = 6.030(1) Angstrom), b = 13.744( 3) Angstrom, c = 5.562(1) Angstrom, beta = 95.75(1)degrees, V = 458.6(2) An gstrom(3), Z = 2, P2(1)/c) has been refined to an R index of 0.043 (wR = 0. 108). The structure is similar to that previously determined for synthetic Cu5Se2O8Cl2 It is based on the unbranched zweier chains {uB, 1(infinity)(1) } [O2Cu5] running parallel to the c axis which are composed of [OCu4] oxoce ntered copper tetrahedra linked through corners and edges in turn. The pyra midal (SeO3) groups are in "face-to-face" positions relative to the [OCu4] tetrahedra and together with the oxocentered chains form the more complex c hains {[O2Cu5](SeO3)(2)} lying side by side in the (010) plane. The chlorid e anions are located between the chains to link them into a three-dimension al framework. The main structural features of other inorganic compounds bas ed on single chains of oxocentered condensed copper tetrahedra are discusse d in comparison.