Max Planck Institut für Chemische Physik fester Stoffe, Nöthnitzer Straße 40, 01187 Dresden, Germany.
Dalton Trans. 2014 Feb 7;43(5):2140-6. doi: 10.1039/c3dt52775a.
The semiconducting compound BaRh2Si9 is a new kind of intermetallic clathrate. It was obtained by reacting BaSi, Rh and Si at 950 °C. The crystal structure (space group C2/c; Pearson symbol mC48, a = 6.2221(5) Å, b = 21.399(2) Å, c = 6.2272(5) Å, β = 90.306(7)°) displays a covalently bonded Rh-Si framework, in which four-connected Si atoms partly show unusually small bond angles. The Ba atoms are encapsulated in large polyhedral cages formed by 18 Si and 4 Rh atoms. The compound is a diamagnetic p-type semiconductor, which is in agreement with band structure calculations resulting in a band gap of 0.12 eV. Quantum chemical calculations reveal positively charged Ba atoms (Ba(+1.3)) and negatively charged Rh atoms (Rh(-1)). Si atoms with neighboring Rh atoms are positively charged, while those connected only with Si atoms are negatively charged.
半导体化合物 BaRh2Si9 是一种新型的金属互化物笼状化合物。它是通过在 950°C 下使 BaSi、Rh 和 Si 反应而得到的。晶体结构（空间群 C2/c；Pearson 符号 mC48，a = 6.2221(5) Å，b = 21.399(2) Å，c = 6.2272(5) Å，β = 90.306(7)°）显示出共价键合的 Rh-Si 骨架，其中四连接的 Si 原子部分显示出异常小的键角。Ba 原子被封装在由 18 个 Si 和 4 个 Rh 原子形成的大多面体笼中。该化合物是一种抗磁性 p 型半导体，这与导致 0.12eV 能带间隙的能带结构计算结果一致。量子化学计算表明存在带正电荷的 Ba 原子（Ba(+1.3)）和带负电荷的 Rh 原子（Rh(-1)）。与 Rh 原子相邻的 Si 原子带正电荷，而仅与 Si 原子相连的 Si 原子带负电荷。
