Synthesis, Structural Evolution, and Theoretical and Physical Studies of the Novel Compounds M2Mo9S11 (M = K, Rb) and Related Metastable Materials Cux
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- 作者：Soazig Picard ; Jean-Franç ; ois Halet ; Patrick Gougeon ; and Michel Potel
- 刊名：Inorganic Chemistry
- 出版年：1999
- 出版时间：October 4, 1999
- 年：1999
- 卷：38
- 期：20
- 页码：4422 - 4429
- 全文大小：136K
- 年卷期：v.38,no.20(October 4, 1999)
- ISSN：1520-510X
文摘
The new isostructural K2Mo9S11 and Rb2Mo9S11 phases were prepared by solid-state reaction at 1500 
C in asealed molybdenum crucible. Both compounds crystallize in the trigonal space group (SG) R
c, Z = 6, a =9.271(1) Å, c = 35.985(9) Å and a = 9.356(2) Å, c = 35.935(9) Å for the K and Rb compounds, respectively,in the hexagonal setting. Their crystal structures were determined from single-crystal X-ray diffraction data andconsist of interconnected Mo9S11 units forming an original and unprecedented three-dimensional framework.Extended Hückel tight-binding (EHTB) calculations carried out on K2Mo9S11 indicate that such compounds areelectron-deficient and may be reduced without altering the arrangement of the Mo9S11 units. This was verified bythe insertion of copper into K2Mo9S11 by topotactic oxydo-reduction reaction, which leads to the new metastableCu2K1.8Mo9S11 compound (SG Rc, a = 9.4215(4) Å, c = 35.444(2) Å, Z = 6). The potassium nonstoichiometryof this quaternary phase was confirmed by deintercalation of the copper in a HCl 12 M solution at 80 C, leadingto the K1.8Mo9S11 phase (SG Rc, a = 9.2801(8) Å, c = 35.833(7) Å, Z = 6). The X-ray single-crystal structuresof K1.8Mo9S11 and Cu2K1.8Mo9S11 are also described. Electrical resistivity measurements carried out on singlecrystals of K2Mo9S11 and Cu2K1.8Mo9S11 indicate that the former is metallic whereas the latter is semiconducting,as expected from EHTB calculations. Magnetic and electrical resistivity measurements performed on K1.8Mo9S11reveal a superconducting behavior below 4.5 K.
C in asealed molybdenum crucible. Both compounds crystallize in the trigonal space group (SG) Rc, Z = 6, a =9.271(1) Å, c = 35.985(9) Å and a = 9.356(2) Å, c = 35.935(9) Å for the K and Rb compounds, respectively,in the hexagonal setting. Their crystal structures were determined from single-crystal X-ray diffraction data andconsist of interconnected Mo9S11 units forming an original and unprecedented three-dimensional framework.Extended Hückel tight-binding (EHTB) calculations carried out on K2Mo9S11 indicate that such compounds areelectron-deficient and may be reduced without altering the arrangement of the Mo9S11 units. This was verified bythe insertion of copper into K2Mo9S11 by topotactic oxydo-reduction reaction, which leads to the new metastableCu2K1.8Mo9S11 compound (SG Rc, a = 9.4215(4) Å, c = 35.444(2) Å, Z = 6). The potassium nonstoichiometryof this quaternary phase was confirmed by deintercalation of the copper in a HCl 12 M solution at 80 C, leadingto the K1.8Mo9S11 phase (SG Rc, a = 9.2801(8) Å, c = 35.833(7) Å, Z = 6). The X-ray single-crystal structuresof K1.8Mo9S11 and Cu2K1.8Mo9S11 are also described. Electrical resistivity measurements carried out on singlecrystals of K2Mo9S11 and Cu2K1.8Mo9S11 indicate that the former is metallic whereas the latter is semiconducting,as expected from EHTB calculations. Magnetic and electrical resistivity measurements performed on K1.8Mo9S11reveal a superconducting behavior below 4.5 K.