A new approach to structural description of complex polyhedra containing polychalcogenide anions

Abstract

Because of the occurrence of polyanionic groups, in particular of (X₂)²⁻ pairs, that are found along with the monoatomic ligands, rather complex coordination groups (M(X_i)_mX_n) (with i=2 in most cases) are encountered in transition metal chalcogenide families. In order to facilitate the classification and the description of most phases of those families, a general method to generate and to classify (M(X_i)_mX_n) polyhedra is introduced. With this method it is possible to visualize the links between coordination groups, either directly through common coordination anions or indirectly through polyanionic bridges. It is shown how the proposed procedure simplifies the understanding of the structural array of numerous complex compounds, in particular in the organo-halogeno-chalcogenides, halogeno-chalcogenides and chalcogeno-phosphates of transition metals. Furthermore, the way the developed method allows comparative studies and offers the possibility of conceiving new phases is exposed.