Synthese, Charakterisierung und strukturchemische Aspekte von Kupfer- und Silberchalkogenohalogeniden sowie von Halogeno- und Oxochalkogenaten(IV)

The main focus of the present work was the synthesis and characterization of copper-
and silverchalcogenohalides as well as chalcogenates(IV). All compounds except the
oxoselenates(IV) were obtained by “hydrothermal synthesis with concentrated
hydrohalide acids”. The following new compounds were prepared: Ag6GeS4X2 (X =
Cl, Br, I), AgICh3 (Ch = Se, Te), CuTe3.75I16, Cs2SeBr6, 4CoSeO3×3H2O, Co(HSeO3)2,
Cs2Co(HSeO3)2Cl2, Cs2MII
3(SeO3)4×18H2O (MII = Co, Ni).
While Ag6GeS4I2 is a typical member of the argyrodite family, the equally composed
compounds Ag6GeS4Cl2 and Ag6GeS4Br2 crystallize in a new structure type. The
anionic partial structure is closely related to the AlB2-structure.
The compounds AgICh3, which crystallize isotypically to CuBrSe3, consist of
formally neutral, cyclohexane-analogue Ch6 rings embedded in a matrix of AgI. In
addition to the structural investigations, density functional tight binding calculations
were performed.
CuTe3.75I16 can be described on the basis of a hexagonal close packing of iodine. The
characteristic of this compound is a highly anisotropic, not fully occupied Teposition
caused by a positional disorder.
Contrary to the compound 4CoSeO3×3H2O, which crystallizes isotypically to the Mn
and Cd species, Cs2Co(HSeO3)2Cl2 represents a new structure type.
So far the solids Cs2MII
3(SeO3)4×18H2O are the only known quasi-ternary oxoselenates(
IV), where the metal-cations are exclusively coordinated by the oxygen atoms
of the water molecules of crystallization.