Fachrichtung Chemie und Lebensmittelchemie, Technische Universität Dresden, 01062 Dresden (Germany).
Angew Chem Int Ed Engl. 2014 Mar 17;53(12):3254-8. doi: 10.1002/anie.201309460. Epub 2014 Feb 12.
The heterogeneous reaction of crystals of the novel intermetallic subhalide Bi12 Rh3 Cl2 with a solution of n-butyllithium at 70 °C led to the complete topochemical exchange of chloride ions for bismuth atoms, that is, the transformation into the isostructural metastable intermetallic superconductor Bi14 Rh3. The crystals underwent the reductive pseudomorphosis almost unchanged except some fissures perpendicular to the a-axis. Detailed inspections of the transformed crystals by electron microscopy indicated no volume defects that would indicate internal chemical reactions. Thus, extensive mass transport must have occurred through the seemingly dense crystal structure. An efficient transport mechanism, based on an unusual breathing mode of the three-dimensional network formed by edge-sharing [RhBi8 ] cubes and antiprisms, is proposed. The replacement of ionic interaction in the chloride by metallic bonding in the binary intermetallic compound closes the pseudo gap in the density of states at the Fermi level. As a result, the rod-packing of conducting, yet electrically isolated strands of [RhBi8] cubes in Bi12 Rh3 Cl2 turns into the three-dimensional metal Bi14 Rh3.
新型金属间亚卤化物 Bi12 Rh3 Cl2 的晶体与正丁基锂溶液在 70°C 下的多相反应导致氯离子完全进行拓扑化学交换成铋原子，即转化为同构的亚稳态超导金属间化合物 Bi14 Rh3。除了一些垂直于 a 轴的裂缝外，晶体几乎没有发生任何变化。通过电子显微镜对转化后的晶体进行详细检查，没有发现表明内部化学反应的体积缺陷。因此，大量物质必须通过看似致密的晶体结构进行传输。提出了一种基于由共享边的[RhBi8] 立方体和反棱柱体形成的三维网络的不寻常呼吸模式的有效传输机制。在二元金属间化合物中，用金属键取代氯化物中的离子相互作用，在费米能级处的态密度中闭合了赝隙。结果，在 Bi12 Rh3 Cl2 中，导电但电隔离的[RhBi8] 立方体的棒状堆积转变为三维金属 Bi14 Rh3。
