Department of Inorganic Chemistry, University of Cologne, Greinstraße 6, 50939 Cologne, Germany.
Inorg Chem. 2012 Nov 5;51(21):11356-64. doi: 10.1021/ic300838a. Epub 2012 Oct 5.
The structures of two new cubic {TnLa(3)}Br(3) (Tn = Ru, Ir; I4(1)32, Z = 8; Tn = Ru: a = 12.1247(16) Å, V = 1782.4(4) Å(3); Tn = Ir: a = 12.1738(19) Å, V = 1804.2(5) Å(3)) compounds belonging to a family of reduced rare-earth metal halides were determined by single-crystal X-ray diffraction. Interestingly, the isoelectronic compound {RuLa(3)}I(3) crystallizes in the monoclinic modification of the {TnR(3)}X(3) family, while {IrLa(3)}I(3) was found to be isomorphous with cubic {PtPr(3)}I(3). Using electronic structure calculations, a pseudogap was identified at the Fermi level of {IrLa(3)}Br(3) in the new cubic structure. Additionally, the structure attempts to optimize (chemical) bonding as determined through the crystal orbital Hamilton populations (COHP) curves. The Fermi level of the isostructural {RuLa(3)}Br(3) falls below the pseudogap, yet the cubic structure is still formed. In this context, a close inspection of the distinct bond frequencies reveals the subtleness of the structure determining factors.
两种新型立方 {TnLa(3)}Br(3)（Tn = Ru、Ir；I4(1)32，Z = 8；Tn = Ru：a = 12.1247(16) Å，V = 1782.4(4) Å(3)；Tn = Ir：a = 12.1738(19) Å，V = 1804.2(5) Å(3)）化合物的结构通过单晶 X 射线衍射确定。有趣的是，等电子化合物 {RuLa(3)}I(3) 以 {TnR(3)}X(3) 族的单斜晶型结晶，而 {IrLa(3)}I(3) 被发现与立方 {PtPr(3)}I(3) 同构。通过电子结构计算，在新型立方结构的 {IrLa(3)}Br(3) 中在费米能级处识别出赝能隙。此外，结构试图通过晶体轨道哈密顿人口（COHP）曲线优化（化学）键合。等结构的 {RuLa(3)}Br(3) 的费米能级低于赝能隙，但仍形成立方结构。在这种情况下，对不同键频的仔细检查揭示了结构决定因素的微妙之处。
