Stuffed graphite-like vs. stuffed diamond-like structures of the 18 valence electron compounds REAuSn (RE = Sc, Y, La-Nd, Sm, Gd-Lu)

Abstract

18-electron compounds REML (RE = rare earth metal; M = Cu, Ag, Au; L = Ge, Sn) can adopt either the stuffed graphite-like (P6 3mc) or the stuffed diamond-like (F4̄3m) structure. To understand why one structure is favored over the other, we carried out density functional theory electronic structure calculations for a number of REAuSn compounds. The stuffed graphite-like and stuffed diamond-like structures of an 18-electron compound REAuSn are quite similar in their electronic structures with the Au atoms best described as existing as anions. The diamond-like REML becomes possible only when the RE 3+ ion is small and the M-L bond is long. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.