%0 Journal Article
%T <br>
%A 沈艳芳
%A 程龙玖
%J 物理化学学报
%D 2018
%R 10.3866/PKU.WHXB201712151
%X 基于理论计算，我们报道了Td对称性的[Pd4(μ3-SbH3)4(SbH3)4]团簇及一系列类似物的结构与成键。成键分析表明：每个Pd原子都是sp3杂化，其10个价电子与四个配体提供的8个价电子，满足18电子规则。并且，每个Pd原子与四个桥连的SbH3配体可以形成四个离域的四中心两电子超级σ键或八中心两电子键。一方面，根据超原子网络模型，这个钯团簇可以描述成四个2电子的超原子网络。另一方面，凝胶模型表明，它可以合理化的作为电子组态是1S21P6的8电子超原子。与此同时，d10…d10闭壳层相互作用在稳定Pd4四面体结构中起到了关键性的作用。密度泛函理论计算表明：Td对称性[Pd4(μ3-SbH3)4(SbH3)4]团簇表现出高度稳定性，具有充满的电子壳层，大的HOMO-LUMO带隙(2.84 eV)以及负的核独立化学位移(NICS)值。此外，基于[Pd4(μ3-SbH3)4(SbH3)4]结构与成键模式，我们设计了一系列稳定的类似物，其有可能被实验合成出来。<br>Motivated by the unusual structure of the [Pd4(μ3-SbMe3)4(SbMe3)4] cluster, which is composed of a tetrahedral (Td) Pd(0) core with four terminal SbMe3 ligands and four triply bridging SbMe3 ligands capping the four triangular Pd3 faces (J. Am. Chem. Soc. 2016, 138, 6964), we performed a computational study of the structure and bonding characteristics of the Td [Pd4(μ3-SbH3)4(SbH3)4] cluster and a series of its analogues. The Td structure of the [Pd4(μ3-SbH3)4(SbH3)4] cluster could be explained by the cluster electron-counting rules based on the 18-electron rule for transition-metal centers; each sp3 hybridized Pd atom contributed ten valence electrons, and eight valence electrons were provided by one terminal SbH3 and three bridging μ3-SbH3 ligands. The [Pd4(μ3-SbH3)4(SbH3)4] cluster had a count of 104 valence electrons in total; chemical bonding analysis indicated that the cluster featured twenty electron lone pairs generated by d orbital of the four Pd atoms, twenty-four Sb―H σ bonds, four terminal Pd―Sb σ bonds, and four delocalized bonds. There were two bonding patterns of the eight delocalized electrons between the four capping Sb atoms and the Pd4 core. The first pattern was based on the superatom-network (SAN) model, whereby the palladium cluster could be described as a network of four 2e– superatoms. The second pattern was based on the spherical jellium model, whereby the cluster could be rationalized as an 8e– [Pd4(μ3-SbH3)4] superatom with 1S21P6 electronic configuration. The density functional theory (DFT) calculations showed that the Td [Pd4(μ3-SbH3)4(SbH3)4] cluster had a large HOMO-LUMO (HOMO: highest occupied molecular orbital; LUMO: lowest unoccupied molecular orbital) energy gap (2.84 eV) and a negative nucleus-independent chemical shift (NICS) value (-12) at the center of the [Pd4(μ3-SbH3)4(SbH3)4] cluster, indicating its high chemical stability and aromaticity. Furthermore, the NICS values in the range of 0–0.30 nm of the [Pd4(μ3-SbH3)4] motifs were much more negative than those of [Pd4(SbH3)4] in the same range, revealing that the overall stability of [Pd4(μ3-SbH3)4(SbH3)4] was likely derived from the
%U http://www.whxb.pku.edu.cn/CN/Y2018/V34/I7/830