Gold-gold bonding: The key to stabilizing the 19-electron ternary phases LnAuSb (Ln = La-Nd and Sm)

Elizabeth M. Seibel, Leslie M. Schoop, Weiwei Xie, Quinn D. Gibson, James B. Webb, Michael K. Fuccillo, Jason W. Krizan, Robert J. Cava

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

(Chemical Equation Presented) We report a new family of ternary 111 hexagonal LnAuSb (Ln = La-Nd, Sm) compounds that, with a 19 valence electron count, has one extra electron compared to all other known LnAuZ compounds. LaAuSb, CeAuSb, PrAuSb, NdAuSb, and SmAuSb crystallize in the YPtAs-type structure, and have a doubled unit cell compared to other LnAuZ phases as a result of the buckling of the Au-Sb honeycomb layers to create interlayer Au-Au dimers. The dimers accommodate the one excess electron per Au and thus these new phases can be considered Ln23+(Au-Au)0Sb23-. Band structure, density of states, and crystal orbital calculations confirm this picture, which results in a nearly complete band gap between full and empty electronic states and stable compounds; we can thus present a structural stability phase diagram for the LnAuZ (Z = Ge, As, Sn, Sb, Pb, Bi) family of phases. Those calculations also show that LaAuSb has a bulk Dirac cone below the Fermi level. The YPtAs-type LnAuSb family reported here is an example of the uniqueness of gold chemistry applied to a rigidly closed shell system in an unconventional way.

Original languageEnglish (US)
Pages (from-to)1282-1289
Number of pages8
JournalJournal of the American Chemical Society
Volume137
Issue number3
DOIs
StatePublished - Jan 28 2015

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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