Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
Inorg Chem. 2011 Nov 7;50(21):10949-55. doi: 10.1021/ic201492z. Epub 2011 Oct 12.
Four examples of R(5)Au(2)Te(2) (vec = 29 e(-); R = Lu, Ho, Dy, Y) have been synthesized by high-temperature solid-state techniques, isotypic examples of Tm(5)Sb(2)Si(2) (vec = 33 e(-)) and binary Eu(5)As(4) (vec = 30 e(-)). The crystal structure was established for Lu(5)Au(2)Te(2), (orthorhombic Cmce (No. 64), a = 15.056(2), b = 7.749(1), c = 7.754(1) Å, and Z = 4), in which pairs of tellurium layers alternate with two-dimensional (2D) Lu(5)Au(2) slabs that are aggregated in such a way that each Au(2)-centered bi-trigonal prism (BTP) of Lu interconnects four other identical units, with the remaining cavities filled by nominal body-centered Lu cubes. The metal-metal aggregation in this structure provides a novel building unit in ternary rare-earth-metal-rich tellurides. Linear-muffin-tin-orbital (LMTO) electronic structure calculations and COHP analyses reveal that Lu(5)Au(2)Te(2) is a poor metal with Au(2) dimers and strong polar Lu-Au and Lu-Te interactions. The first theoretical analysis of the binary parent structure Eu(5)As(4) (vec = 30 e(-)) provides a simpler description of the equivalent orbital interactions and a closed shell gap in terms of the idealized (Eu(2+))(5)(As(2)(4-))(As(3-))(2) representation, particularly for the explicit filled As(2) levels σ(s), σ(s), σ(p), π, π, plus empty σ(p)*. Crystal Orbital Hamilton Population (-COHP) data illuminate the prominent roles that polar bonding of Eu-As or Lu-Te and Lu-Au and relativistic effects with gold play in these, the former corresponding to 83% and 86% of the total Hamilton population for Eu(5)As(4) and Lu(5)Au(2)Te(2), respectively.
四种 R(5)Au(2)Te(2)（vec = 29 e(-)；R = Lu、Ho、Dy、Y）的例子已经通过高温固态技术合成，它们是 Tm(5)Sb(2)Si(2)（vec = 33 e(-)）和二元 Eu(5)As(4)（vec = 30 e(-)）的同型物。Lu(5)Au(2)Te(2)的晶体结构已经建立，（正交 Cmce（No. 64），a = 15.056(2)，b = 7.749(1)，c = 7.754(1) Å，Z = 4），其中碲层对与二维（2D）Lu(5)Au(2)片交替，这些片以这样的方式聚集，使得每个由 Au(2) 为中心的双三角棱柱（BTP）连接四个其他相同的单元，剩余的空腔由标称体心 Lu 立方体填充。该结构中的金属-金属聚集为三元富稀土金属碲化物提供了一种新的构建单元。线性 muffin-tin-orbital（LMTO）电子结构计算和 COHP 分析表明，Lu(5)Au(2)Te(2)是一种贫金属，其中 Au(2) 二聚体和强烈的极化 Lu-Au 和 Lu-Te 相互作用。对二元母体结构 Eu(5)As(4)（vec = 30 e(-)）的首次理论分析提供了一种更简单的描述等价轨道相互作用和封闭壳隙的方法，以理想化的（Eu(2+)）(5)(As(2)(4-))(As(3-))(2)表示，特别是对于明确填充的 As(2)能级 σ(s)、σ(s)、σ(p)、π、π，外加空的 σ(p)*。晶体轨道哈密顿人口 (-COHP) 数据说明了极化 Eu-As 或 Lu-Te 和 Lu-Au 键合以及金的相对论效应对这些键合的突出作用，前者分别对应于 Eu(5)As(4)和 Lu(5)Au(2)Te(2)的总哈密顿人口的 83%和 86%。
