A one-dimensional metal embedded in salt matrices: Synthesis, modulated crystal structures, electrical conductivity, and chemical bonding of [PdBi<sub>6</sub>][(Bi,Sn)<sub>1–δ</sub>Br<sub>5–δ'</sub>] - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Inorganic and General Chemistry / Zeitschrift für anorganische und allgemeine Chemie Année : 2009

A one-dimensional metal embedded in salt matrices: Synthesis, modulated crystal structures, electrical conductivity, and chemical bonding of [PdBi6][(Bi,Sn)1–δBr5–δ']

Résumé

The metal-rich compounds [PdBi6][(Bi,Sn)1–δBr5–δ'] with δ1 = 2/13, δ'1 = 5/26, or δ2 = δ'2 = 2/12 have been synthesized from Bi2Pd, BiBr3, and Sn at 300 °C. The crystal structures contain intermetallic rods 1[Pd@Bi2/1Bi8/2]2.5+ embedded in salt-like matrices, which consist of groups of bromido-bismuthate(III)-stannate(II) octahedra [(Bi,Sn)nBr4n+2]m– (n = 2, 3) and isolated Br– ions. Metrical incompatibilities of the two subsystems in the crystalline metal-salt- hybrid result in non-stoichiometry of the salt part associated with complex superstructures. The average structure is described in the orthorhombic space group Pmmm with a ≈ 408 pm, b ≈ 2263 pm, c ≈ 849 pm. It feigns statistical distribution of vacancies and orientational disorder of the concatenated octahedra. By choosing the modulation vectors qi = 2/t a* + ½ b* + ½ c* with t1 = 13 or t2 = 12, the additional weak reflections of the diffraction patterns are indexed. Ordered structure models are achieved in the [3+1]-dimensional superspace group Pmmm(α½½)000. Metallic conductivity along [100], i.e. the direction of the 1[Pd@Bi2/1Bi8/2]2.5+ rods, was determined for a single-crystal. One-dimensional band structure calculations reveal Bi p-bands crossing the Fermi level for formula charges higher than 2+. The electron localization indicator (ELI) indicates two-center Bi–Bi bonds as well as multi-center bonds inside the metallic part, while the Bi lone-pairs point towards the non-conducting part of the structure.

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Dates et versions

hal-00501884 , version 1 (13-07-2010)

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Citer

Bernhard Wahl, Lars Kloo, Michael Ruck. A one-dimensional metal embedded in salt matrices: Synthesis, modulated crystal structures, electrical conductivity, and chemical bonding of [PdBi6][(Bi,Sn)1–δBr5–δ']. Journal of Inorganic and General Chemistry / Zeitschrift für anorganische und allgemeine Chemie, 2009, 635 (12), pp.1979. ⟨10.1002/zaac.200900191⟩. ⟨hal-00501884⟩

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