Reactivity of Copper in Molten Polytelluride Salts. K4Cu8Te11, A3Cu8Te10 (A = Rb, Cs), AA’2Cu8Te10 (A, A’ = K, Rb, Cs), and A2BaCu8Te10 (A = K, Rb, Cs): Novel Solids Based on Endohedrally Occupied [Cu8Te12] Dodecahedral Cage-Clusters

Xiang Zhang, Younbong Park, Mercouri G. Kanatzidis, Tim Hogan, Jon L. Schindler, Carl R. Kannewurf, Seeyearl Seong, Thomas Albright

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Abstract

The reaction of copper with molten alkali polytelluride salts led to several novel compounds with a characteristic structural feature based on a pentagonal dodecahedral geometric solid. We report here in detail the synthesis, structure, and chemical, spectroscopic, and charge-transport properties of K4Cu8Te11, A3Cu8Te10, and A2-BaCu8Te10 along with electronic band structure calculations on the two-dimensional Cu8Te10 framework. K4CU8Te11 is monoclinic C2/m with a = 24.086(3) Å, b = 6.821(6) Å, c = 18.461(3) Å, β = 124.45(1)°, V = 2501 Å3 at 23 °C, Z = 4, no. of data used (I > 3σ(I)) 2029, no. of variables 121. The final R/Rw was 2.5%/3.7%. Rb3Cu8Te10 is monoclinic C2/m with a = 24.420(11) Å,b = 6.974(6) Å, c = 6.933(1) Å, β= 104.90(1)°, V = 1141 Å3 at 23 °C, Z = 2, no. of data used (I > 3σ(I)) 721, no. of variables, 57 final R/Rw 5.7%/7.3%. Cs8Cu8Te10 is orthorhombic Immm with a = 7.053(2) Å, b = 24.159(3) Å, c = 6.935(3) Å, V = 1182 Å3 at 23 °C, Z = 2, no. of data used (I > 3σ(I)) 839, no. of variables 36 final R/Rw3.2%/5.0%. K0.9CS2.1Cu8Te10 is orthorhombic Immm with a = 7.023(3) Å, b = 23.895(6) Å c = 6.908(3) Å, V = 1159 Å3 at 23 °C, Z = 2 no. of data used (I > 3σ(I)) 625, no. of variables 37, final R/Rw3.5%/3.0%. K2BaCu8Te10 is monoclinic C2/m with a = 23.245(5) Å, b = 6.950(5) Å, c = 7.061(5) Å, β = 101.23(4)°, V = 1119 Å3 at 23 °C, Z = 2, no. of data used (I > 3σ(I)) 1445, no. of variables 57, final R/Rw8.8%/11.3%. Cs2BaCu8Te10 is orthorhombic Immm with a = 7.109(2) Å, b = 23.761(16) Å, c = 6.966(3) Å, V = 1177 Å3 and Z = 2, no. of data used (I > 3σ(I)) 795, no. of variables 35, final R/Rw3.0%/6.0%. All compounds reported here, except K4Cu8Te11, contain the same layered Cu/Te framework built from the [Cu8Te12] pentagonal dodecahedral cage-cluster. This characteristic cluster, however, is also the building block of the three-dimensional structure of K4Cu8Te11. The structure consists of condensed pentagonal dodecahedral Cu8(Te2)6 clusters sharing Te—Te edges. Each Cu8(Te2)6 dodecahedral cluster encapsulates an alkali or a Ba2+ ion. The A3Cu8Te10 are mixed valence compounds and exhibit metallic properties as demonstrated by electrical conductivity, thermoelectric power, and magnetic susceptibility measurements. K4Cu8Te11 and A2BaCu8Te10 are electron-precise semiconductors with narrow band gaps. Extended-Hückel theoretical tight binding calculations on A3Cu8Te10 confirm the metallic nature of the materials.

Original languageEnglish
Pages (from-to)10300-10310
Number of pages11
JournalJournal of the American Chemical Society
Volume117
Issue number41
DOIs
Publication statusPublished - 1995

ASJC Scopus subject areas

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

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