Crystal chemistry of inorganic compounds based on chains of oxocentered tetrahedra III. Crystal structure of georgbokiite, Cu5O2(SeO3)2Cl2 1

The monoclinic crystal structure of georgbokiite, a new mineral with the chemical composition Cu5O2(SeO3)2Cl2 (a = 6.030(1) Å), b = 13.744(3) Å, c = 5.562(1) Å, β = 95.75(1)°, V = 458.6(2) Å3, Z = 2, P21/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, 1χ 1} [O2Cu5] running parallel to the c axis which are composed of [OCu4] oxocentered copper tetrahedra linked through corners and edges in turn. The pyramidal (SeO3) groups are in “face-to-face” positions relative to the [OCu4] tetrahedra and together with the oxocentered chains form the more complex chains {[O2Cu5](SeO3)2} lying side by side in the (010) plane. The chloride anions are located between the chains to link them into a three-dimensional framework. The main structural features of other inorganic compounds based on single chains of oxocentered condensed copper tetrahedra are discussed in comparison.