Han Bao-Liang, Liu Zhen, Feng Lei, Wang Zhi, Gupta Rakesh Kumar, Aikens Christine M, Tung Chen-Ho, Sun Di
Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, People's Republic of China.
Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, United States.
J Am Chem Soc. 2020 Mar 25;142(12):5834-5841. doi: 10.1021/jacs.0c01053. Epub 2020 Mar 13.
Because of the typical instability of copper nanoclusters, atom-precise structural elucidation of these nanoclusters has remained elusive. Herein, we report an air- and moisture-stable 23-copper nanocluster ( or ) isolated from the reaction of Cu(CFCOO), BuC≡CH, Cu powder, and PhSiH using a gradient reduction (Cu → Cu → Cu) strategy (GRS), which is competent for controlling the kinetics of the reduction reaction, thus avoiding formation of pure Cu complexes or large Cu nanoparticles. The solid-state structure of the Cu nanocluster shows a rare [Cu] tetrahedral kernel surrounded by an outer Cu shell, which is protected by BuC≡C and CFCOO ligands. The Cunanocluster is a rare four-electron superatom with a 1S1P electronic shell closure and can be crystallized in two polymorphs (3 and 3̅) depending on the solvent used. The crystallization of in the 3 space group is mainly governed by van der Waals forces and C-H···F interactions, whereas additional intermolecular C-H···Cl interactions are responsible for the 3̅ space group of . This work not only shows the ingenuity of a gradient reduction strategy for the synthesis of copper nanoclusters but also provides a better fundamental understanding of how to produce the polymorphic copper nanoclusters in a precisely tunable fashion.
由于铜纳米团簇具有典型的不稳定性，对这些纳米团簇进行精确的原子结构解析一直难以实现。在此，我们报道了一种通过梯度还原（Cu→Cu→Cu）策略（GRS）从Cu(CFCOO)、BuC≡CH、铜粉和PhSiH的反应中分离出的空气和水分稳定的23铜纳米团簇（或），该策略能够控制还原反应的动力学，从而避免形成纯铜配合物或大的铜纳米颗粒。铜纳米团簇的固态结构显示出一种罕见的[Cu]四面体核，周围是一个外部铜壳，由BuC≡C和CFCOO配体保护。该铜纳米团簇是一种罕见的具有1S1P电子壳层封闭的四电子超原子，根据所用溶剂的不同，可以结晶成两种多晶型物（3和3̅）。在3空间群中结晶主要受范德华力和C-H···F相互作用控制，而额外的分子间C-H···Cl相互作用则导致其在3̅空间群中结晶。这项工作不仅展示了用于合成铜纳米团簇的梯度还原策略的独创性，还为如何以精确可调的方式制备多晶型铜纳米团簇提供了更好的基础理解。
