Hang Tran Dieu, Hung Huynh Minh, Nguyen Huyen Thi, Nguyen Minh Tho
Department of Chemistry, University of Leuven, B-3001 Leuven, Belgium.
J Phys Chem A. 2015 Jun 18;119(24):6493-503. doi: 10.1021/acs.jpca.5b02492. Epub 2015 Jun 10.
The ground state geometries, electronic structures, and thermochemical properties of binary alkaline-earth-metal silicon clusters Si3M with M = Be, Mg, Ca in neutral, cationic, and anionic states were investigated using quantum chemical computations. Lowest-lying isomers of the clusters were determined on the basis of the composite G4 energies. Along with total atomization energies, thermochemical parameters were determined for the first time by means of the G4 and coupled-cluster theory with complete basis set CCSD(T)/CBS approaches. The most favored equilibrium formation sequences for Si3M clusters emerge as follows: all Si3M(+/0/-) clusters are formed by attaching the M atom into the corresponding cation, neutral and anion silicon trimer Si3(+/0/-), except for the Si3Mg(+) and Si3Ca(+) where the metal cations are bound to the neutral Si3. The resulting mixed tetramers exhibit geometrical and electronic features similar to those of the pure silicon tetramer Si4(+/0/-). Electron localization function (ELF) and ring current analyses point out that the σ-aromatic character of silicon tetramer remains unchanged upon substituting one Si atom by one alkaline-earth-metal atom.
利用量子化学计算方法，研究了二元碱土金属硅簇Si3M（M = Be、Mg、Ca）在中性、阳离子和阴离子状态下的基态几何结构、电子结构和热化学性质。基于复合G4能量确定了这些簇的最低能量异构体。除了总原子化能外，还首次通过G4和完全基组耦合簇理论CCSD(T)/CBS方法确定了热化学参数。Si3M簇最有利的平衡形成顺序如下：所有Si3M(+/0/-)簇都是通过将M原子连接到相应的阳离子、中性和阴离子硅三聚体Si3(+/0/-)上形成的，但Si3Mg(+)和Si3Ca(+)除外，其中金属阳离子与中性Si3结合。由此产生的混合四聚体表现出与纯硅四聚体Si4(+/0/-)相似的几何和电子特征。电子定位函数（ELF）和环流分析指出，在用一个碱土金属原子取代一个Si原子后，硅四聚体的σ-芳香性保持不变。
