Xu Jian, Yao Shenglai, Postils Verònica, Matito Eduard, Lorent Christian, Driess Matthias
Metalorganic and Inorganic Materials, Department of Chemistry, Technische Universität Berlin 10623 Berlin Germany
Theoretical Chemistry Group, Molecular Chemistry, Materials and Catalysis Division (MOST), Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain Place Louis Pasteur 1 B-1348 Louvain-la-Neuve Belgium.
Chem Sci. 2025 May 19. doi: 10.1039/d5sc02644j.
Utilizing the chelating bis(silylenyl)carborane [Si(-CB)Si] (A, Si = PhC(NBu)Si, CB = -CBH) ligand, a series of unprecedented bis(silylene)-stabilized monovalent bismuth complexes {[Si(-CB)Si]Bi}X (X = I, 1a; X = OTf, 1b), {[Si(-CB)Si]Bi} (2) and ({[Si(-CB)Si]Bi}K(thf)) ([3K(thf)]) were synthesized, isolated and characterized. The electronic structures of the bismuth complexes are significantly influenced by the redox-active nature of the CB scaffold. Remarkably, a one-electron injection to 1b with KC does not furnish a Bi complex but reduction of the CB backbone giving rise to the neutral Bi radical complex 2. Notably, compound 1b can also undergo a two-electron reduction with two molar equiv. of potassium naphthalenide, resulting in the formation of the diamagnetic Bi anion complex 3 as a dimer bridged two K(thf) cations. Density functional theory calculations reveal that upon reduction from 1a to 2, and 2 to 3, the added electron predominantly localizes within the carborane cage, with a marked preference for the carbon atoms, ruling out that these species exhibit characteristics of a molecular bismuth(0) electride.
利用螯合双（硅烯基）碳硼烷[Si(-CB)Si]（A，Si = PhC(NBu)Si，CB = -CBH）配体，合成、分离并表征了一系列前所未有的双（硅烯）稳定的一价铋配合物{[Si(-CB)Si]Bi}X（X = I，1a；X = OTf，1b）、{[Si(-CB)Si]Bi}（2）和（{[Si(-CB)Si]Bi}K(thf)）（[3K(thf)]）。铋配合物的电子结构受到CB支架的氧化还原活性性质的显著影响。值得注意的是，用KC对1b进行单电子注入并没有得到铋配合物，而是使CB主链还原，生成了中性的铋自由基配合物2。值得注意的是，化合物1b也可以用两摩尔当量的萘基钾进行双电子还原，生成抗磁性的铋阴离子配合物3，它是由两个K(thf)阳离子桥联的二聚体。密度泛函理论计算表明，从1a还原到2以及从2还原到3时，添加的电子主要定域在碳硼烷笼内，且明显偏向于碳原子，排除了这些物种表现出分子铋(0)电子化物的特征。
