Multifaceted Sn–Sn bonding in the solid state. Synthesis and structural characterization of four new Ca–Li–Sn compounds
Multifaceted Sn–Sn bonding in the solid state. Synthesis and structural characterization of four new Ca–Li–Sn compounds
复制标题
固态多面 Sn-Sn 键合。
DOI：
10.1039/c9dt02803j
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发表时间：
2019
影响因子：
4
通讯作者：
Bobev, Svilen
中科院分区：
文献类型：
--
作者：
Ovchinnikov, Alexander;Bobev, Svilen
采用金属助熔剂法和常规高温合成法在Ca-Li-Sn体系中制备了四种新型三元相。所获得的每一种组合物都代表了自己的（新的）结构类型，并且结构具有不同的多阴离子锡单元。Ca4LiSn6（空间群Pbcm， Pearson符号oP44）容纳无限链，由类似环戊烷的[Sn5]环组成，由Sn原子桥接。这种结构中的锡原子是二键和三键的。Ca9Li6+ xSn13-x的阴离子亚结构（x≈0.28，空间群C2/m， Pearson符号mS56）表现出Li和Sn的广泛混合以及Sn原子间单键和高价相互作用的结合。第三种化合物Ca2LiSn3（空间群Pmm2， Pearson符号oP18）具有准二维多阴离子亚基和Sn原子的各种配位环境，其结构也具有明显的高价键。Ca9-xLi2Sn10 （x≈0.16，空间群C2/m， Pearson符号mS42）结构中存在具有复杂顺式和反式Sn-Sn键拓扑结构的一维[Sn10]链，这种情况下的Sn-Sn键具有介于单键和双键之间的中间结构特征。在Zintl方法的背景下讨论了键的特性，Zintl方法捕捉了主要化学相互作用的本质。这四种化合物的电子结构也用第一性原理计算进行了详细的分析。
Four novel ternary phases have been prepared in the system Ca–Li–Sn using both the metal flux method and conventional high-temperature synthesis. Each of the obtained compositions represents its own (new) structure type, and the structures feature distinct polyanionic Sn units. Ca4LiSn6 (space group Pbcm, Pearson symbol oP44) accommodates infinite chains, made up of cyclopentane-like [Sn5]-rings, which are bridged by Sn atoms. The Sn atoms in this structure are two- and three-bonded. The anionic substructure of Ca9Li6+xSn13–x (x ≈ 0.28, space group C2/m, Pearson symbol mS56) displays extensive mixing of Li and Sn and combination of single-bonded and hypervalent interactions between the Sn atoms. Hypervalent bonding is also pronounced in the structure of the third compound, Ca2LiSn3 (space group Pmm2, Pearson symbol oP18) with quasi-two-dimensional polyanionic subunits and a variety of coordination environments of the Sn atoms. One-dimensional [Sn10]-chains with an intricate topology of cis- and trans-Sn–Sn bonds exist in the structure of Ca9–xLi2Sn10 (x ≈ 0.16, space group C2/m, Pearson symbol mS42), and the Sn–Sn bonding in this case demonstrates the characteristics of an intermediate between single- and double- bond-order. The peculiarities of the bonding are discussed in the context of the Zintl approach, which captures the essence of the main chemical interactions. The electronic structures of all four compounds have also been analyzed in full detail using first-principles calculations.