Fei Wang - Revisiting the Zintl-Klemm Concept II: A2AuBi (A = Alkali Metals)

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  Publication Details (including relevant citation   information):

  Fei Wang, and Gordon J. Miller, Eur. J. of Inorg. Chem., 2011,   26, 3989-3998.


  Alkali metal gold bismuthides, A2AuBi, are   isoelectronic with alkali metal thallides, ATl =   A2TlTl, and yet Na2AuBi adopts an   orthorhombic structure with a 1-D zigzag “ribbon” structural   motif rather than the cubic double diamond structure type of NaTl   as well as Li2AuBi. Using first principles quantum   mechanical calculations applied to A2AuBi,   hypothetical “A2HgPb,” and   A2TlTl, and comprehensively decomposing the   total energies into metallicity, ionicity, and covalency   components to establish parallels with the qualitative   Zintl–Klemm formalism, the factors determining the relative   stability between the zigzag “ribbon” and the diamond network are   examined. An interplay between volume-dependent energy terms,   i.e., metallicity or ionicity, and covalency among the   electronegative components determines which structural motif is   favored. In Na2AuBi, there are two factors stabilizing   the zigzag “ribbon.” Au 5d states significantly interact   with Bi 6p states, especially Au 5dmath image  with Bi 6pz to promote stronger Au–Bi   covalent interactions than in the diamond network. This factor   does not exist in Na2TlTl and   “A2HgPb,” where Hg, Tl, and Pb 5d  states are well localized. Secondly, the zigzag ribbons provide   effective covalent interactions at larger volumes, as in   Na2AuBi, while effective covalent interactions occur   in the diamond network only at smaller volume, as in   Li2AuBi.

  Address (URL): http://onlinelibrary.wiley.com/doi/10.1002/ejic.201100312/abstract