Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.
Phys Chem Chem Phys. 2018 Sep 12;20(35):22498-22509. doi: 10.1039/c8cp03883j.
The most stable geometries of the coinage metal (or regium) atom (Cu, Ag, Au) clusters Mn for n up to 6 are all planar, and adopt the lowest possible spin multiplicity. Clusters with even numbers of M atoms are thus singlets, while those with odd n are open-shell doublets. Examination of the molecular electrostatic potential (MEP) of each cluster provides strong indications of the most likely site of attack by an approaching nucleophile, generally one of two positions. A nucleophile (NH3 or HCN) most favorably approaches one particular M atom of each cluster, rather than a bond midpoint or face. In the closed-shell clusters, the interaction energies are highly dependent upon the intensity of the MEP, but this correlation fades for the open-shell systems studied in this work. The strength of the interaction is also closely related to the basicity of the nucleophile. Regium bond energies can be more than 30 kcal mol-1 and tend to follow the Au > Cu > Ag order. These interaction energies are in large part derived from Coulombic attraction, with a smaller orbital interaction contribution.
货币金属（或类金属）原子（Cu、Ag、Au）簇 Mn 的最稳定几何形状为 n 高达 6 的平面，且采用可能的最低自旋多重度。因此，具有偶数个 M 原子的簇为单重态，而具有奇数 n 的簇为开壳层双重态。对每个簇的分子静电势（MEP）的检查强烈表明了最有可能被接近的亲核试剂攻击的位置，通常是两个位置之一。亲核试剂（NH3 或 HCN）最有利于接近每个簇的一个特定的 M 原子，而不是键的中点或面。在闭壳层簇中，相互作用能高度依赖于 MEP 的强度，但对于本工作中研究的开壳层系统，这种相关性消失。相互作用的强度也与亲核试剂的碱性密切相关。类金属键能超过 30 kcal mol-1，且倾向于遵循 Au > Cu > Ag 顺序。这些相互作用能主要来自库仑吸引力，轨道相互作用贡献较小。
