Synthesis and Crystal Structure of the Trigonal Silver(I) Dithioaurate(I), Ag3AuS2

Abstract

Crystals of the silver(I) dithioaurate(I), Ag3AuS2, were obtained by fusing the elements in the required stoichiometric amounts. Single-crystal X-ray analysis showed that two phases of a slightly different composition coexist in the products of synthesis: a trigonal phase [a = 13.7104(4) Å, c = 17.1170(6) Å, space group R3̅c] and a cubic one [a = 19.3590(7) Å]. The crystal structure was determined for the first phase. The sublattice of sulfur atoms represents a distorted body-centered cubic packing. The structure contains distinct triatomic linear groups (S−Au−S) and Ag atoms surrounded by four S atoms (from four different linear groups). Comparison was made for the trigonal phase under consideration, cubic petzite (Ag3AuTe2) and fischesserite (Ag3AuSe2) and the tetragonal uytenbogaardtite (Ag3AuS2). The trigonal phase Ag3AuS2 cannot be attributed to the petzite group, because it is a new structure type. Unlike generally accepted opinion, the tetragonal uytenbogaardtite is not a petzite type either.