A. N. Nesmeyanov Institute of Organoelement Compounds Russian Academi of Sciences (INEOS RAS) , Moscow, Russia 119991.
J Phys Chem A. 2013 Dec 12;117(49):13138-50. doi: 10.1021/jp405270u. Epub 2013 Dec 2.
Interaction of [Cu2B10H10] with 2,2'-bipyridine (bipy) afforded a novel binuclear discrete complex of the [Cu2(bipy)2B10H10] composition. Two copper(I) atoms coordinate a bridge boron cage through an apical edge and a triangular BBB face situated at its opposite apical vertices to form four 3c2e (CuHB) and one 2c2e Cu-B bonds. The charge density model was obtained by density functional theory calculations of isolated molecule and crystal. The resultant densities were analyzed using the quantum theory of atoms in molecules (QTAIM) and electron localizability indicator (ELI-D). The geometry and the topological parameters of copper(I) coordination environment were found to be sensitive to crystal-field effect. An annulus of flat electron density ρ(r) and small ∇(2)ρ(r) is formed at dianion faces. As a result, some of the expected B-B, Cu-B, or Cu-H bond critical points are absent. The topological instability in the region of multicentered bonds is observed. The Cu-B bonding was found to be presumably electrostatic in nature, which could be the reason of topological isomerism for copper(I) decaborates. The results show that an unambiguous real-space criterion for multicentered bonding between transition metals and polyhedral boron anions is not yet given. The molecular graph for this class of compounds does not provide a definitive picture of the chemical boding and can be complemented with other descriptors, such as virial graphs and the ELI-D distribution.
[Cu2B10H10] 与 2,2'-联吡啶（bipy）相互作用，得到了一种新型双核离散配合物[Cu2(bipy)2B10H10]。两个铜（I）原子通过顶点边缘和位于其相对顶点的三角形 BBB 面与桥接硼笼配位，形成四个 3c2e（CuHB）和一个 2c2e Cu-B 键。孤立分子和晶体的密度泛函理论计算得到了电荷密度模型。使用分子中的原子量子理论（QTAIM）和电子局域化指标（ELI-D）分析了所得密度。发现铜（I）配位环境的几何形状和拓扑参数对晶体场效应敏感。在负离子面上形成了一个扁平电子密度 ρ(r)和小 ∇(2)ρ(r)的环。结果，一些预期的 B-B、Cu-B 或 Cu-H 键临界点不存在。观察到多中心键区域的拓扑不稳定性。发现 Cu-B 键的性质可能是静电的，这可能是铜（I）十硼烷拓扑异构的原因。结果表明，对于过渡金属和多面体硼阴离子之间的多中心键，还没有明确的实空间判据。这类化合物的分子图不能提供化学键的明确图像，并且可以用其他描述符（如 virial 图和 ELI-D 分布）来补充。
