Synthesis and crystal structure of silver–gold sulfide AgAuS. Four-fold interpenetrated three-dimensional [(Au,Ag)10S8]-networks

Abstract

Crystals of the silver(I) thioaurate(I), AgAuS, were obtained by fusing the elements in stoichiometric amounts. The X-ray diffraction analysis showed that the synthesized phase AgAuS represents a new structural type. The unit cell parameters are a = 13.4235(3), c = 9.0873(4) Å, V = 1418.07(6) ų and Z = 24, and the space group is Rm. The sublattice of sulfur atoms has a strongly distorted body-centered cubic packing. All Au atoms are in a typical linear coordination with sulfur ones. Three-quarters of the silver atoms are surrounded by distorted tetrahedra of sulfur atoms, while the rest of the silver atoms are involved in a linear motif typical of Au atoms as well. The resulting motif is composed of four-fold interpenetrating networks of linearly coordinated metals with 2- and 4-connected sulfur atoms: [Au₈^[2]Ag₂^[2]S₆⁽²⁾S₂⁽⁴⁾]. The formula of AgAuS can be represented as Ag₂₄^[4][Au₈^[2]Ag₂^[2]S₈]₄. The features of the AgAuS structure suggest the possibility of wide variation in the Au : Ag ratio.