Beziehungen zwischen Kristallstruktur und 197AuMößbauereffekt ternärer AlkalimetallGold(I)Chalkogenide

197 Au-Mossbauer results are reported for a series of alkali metal gold chalcogenides: Na 3 AuS 2 , KAuS, CsAuS, K 4 Au 6 S 5 , KAuSe, NaAuTe, KAuTe, RbAuTe and CsAuTe. Isomeric shifts (ISs) and quadrupole splittings (QSs) correspond to the region expected for gold atoms of oxidation state + 1 in the QSIS correlation diagram. The compounds with linearly coordinated gold atoms exibit a marked linear relationship between IS and QS. The highest values of QS and IS are found for Na 3 AuS 2 . Progressively lower values are manifested as the chalcogen atom is changed from sulphur to selenium to tellurium or when the alkali metal is exchanged for a less electronegative element respectively. Correspondingly the parameters of alkali metal gold chalcogenides with a smaller content of alkali metal are smaller. The Mossbauer spectra of the ternary tellurides show the expected difference between the threefold-coordinated gold atoms of the layer structures and the twofold-coordinated gold atoms of the chain structures. Eventual AuAu interactions could not be proved by these Mossbauer measurements. The short AuAu distances, detected by X-ray analysis, are possibly van der Waals contacts.