Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany.
J Chem Phys. 2014 Mar 28;140(12):124309. doi: 10.1063/1.4869104.
Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have investigated the extent to which the aluminum moieties within selected magnesium-aluminum clusters are Zintl anions. Magnesium-aluminum cluster anions were generated in a pulsed arc discharge source. After mass selection, photoelectron spectra of MgmAln (-) (m, n = 1,6; 2,5; 2,12; and 3,11) were measured by a magnetic bottle, electron energy analyzer. Calculations on these four stoichiometries provided geometric structures and full charge analyses for the cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra). Calculations revealed that, unlike the cases of recently reported sodium-aluminum clusters, the formation of aluminum Zintl anion moieties within magnesium-aluminum clusters was limited in most cases by weak charge transfer between the magnesium atoms and their aluminum cluster moieties. Only in cases of high magnesium content, e.g., in Mg3Al11 and Mg2Al12 (-), did the aluminum moieties exhibit Zintl anion-like characteristics.
通过阴离子光电子能谱和基于密度泛函理论的计算的协同组合，我们研究了在选定的镁-铝团簇中，铝部分在多大程度上是 Zintl 阴离子。在脉冲电弧放电源中生成镁-铝团簇阴离子。在质量选择之后，通过磁瓶、电子能量分析仪测量 MgmAln（-）（m，n=1，6；2，5；2，12；和 3，11）的光电子能谱。对这四种化学计量比的计算为阴离子和中性团簇对应物提供了团簇阴离子的几何结构和全电荷分析，以及光离解跃迁能（棒状谱）。计算表明，与最近报道的钠-铝团簇的情况不同，在镁-铝团簇中形成铝 Zintl 阴离子部分在大多数情况下受到镁原子与其铝团簇部分之间弱电荷转移的限制。只有在镁含量较高的情况下，例如 Mg3Al11 和 Mg2Al12（-），铝部分才表现出类似于 Zintl 阴离子的特征。
