M2Ba2Sn6 (M =Yb, Ca): Metallic Zintl Phases with a Novel Tin Chain Substructure
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- 作者：Ming-Hui Ge ; John D. Corbett
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：May 14, 2007
- 年：2007
- 卷：46
- 期：10
- 页码：4138 - 4144
- 全文大小：435K
- 年卷期：v.46,no.10(May 14, 2007)
- ISSN：1520-510X
文摘
The compounds M2Ba2Sn6 (M = Yb, Ca) have been synthesized by solid-state reactions in welded Ta tubes athigh temperature. Their structures were determined by single-crystal X-ray diffraction studies to be orthorhombic;space group Cmca (No. 64); Z = 8; a = 15.871(3), 15.912 (3) Å; b = 9.387(2), 9.497(2) Å; c = 17.212(3),17.184(3) Å; and V = 2564.3(9), 2597.0(9) Å3, respectively. These contain infinite tin chains along 
constructedfrom butterflylike 3-bonded Sn tetramers interconnected by pairs of 2-bonded Sn. The chains are further interconnectedinto corrugated layers by somewhat longer Sn-Sn bonds along 
. The compounds with the chains alone would beZintl phases, but the interchain bonding makes them formally one-electron rich per formula unit. The electronicstructures calculated by extended Hückel and TB-LMTO-ASA methods indicate that these compounds are metallicbut with a deep pseudogap at the Fermi level. States that bind the extra electrons lie just below EF and involveimportant Yb(Ca)-Sn contributions. The origin of metallic Zintl phases is briefly discussed.
constructedfrom butterflylike 3-bonded Sn tetramers interconnected by pairs of 2-bonded Sn. The chains are further interconnectedinto corrugated layers by somewhat longer Sn-Sn bonds along . The compounds with the chains alone would beZintl phases, but the interchain bonding makes them formally one-electron rich per formula unit. The electronicstructures calculated by extended Hückel and TB-LMTO-ASA methods indicate that these compounds are metallicbut with a deep pseudogap at the Fermi level. States that bind the extra electrons lie just below EF and involveimportant Yb(Ca)-Sn contributions. The origin of metallic Zintl phases is briefly discussed.