Institute of Chemical Process Fundamentals, Czech Academy of Sciences Prague 6, 165 02, Suchdol 2, Czech Republic.
Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK.
J Mol Model. 2018 Aug 8;24(9):226. doi: 10.1007/s00894-018-3764-y.
Motivated by the known stability of the somewhat unusual BeO rhombus, which features a short Be-Be distance but no direct metal-metal bonding, we investigate the nature of the bonding interactions in the analogous clusters MM'O (M, M' = Be, Mg, Ca). CCSD/cc-pVTZ and CCSD(T)/cc-pVQZ calculations, amongst others, are used to determine optimized geometries and the dissociation energies for splitting the MM'O clusters into metal oxide monomers. The primary tools used to investigate the chemical bonding are the analysis of domain-averaged Fermi holes, including the generation of localized natural orbitals, and the calculation of appropriate two- and three-center bond indices. Insights emerging from these various analyses concur with earlier studies of MO rhombic clusters in that direct metal-metal bonding was not observed in the MM'O rings whereas weak three-center (3c) bonding was detected in the MOM' moieties. In general terms, these mixed MM'O clusters exhibit features that are intermediate between those of MO and M'O, and the differences between the M and M' atoms appear to have little impact on the overall degree of 3c MOM' bonding. Graphical abstract Bonding situation in MM'O clusters (M, M' = Be, Mg, Ca).
受已知 BeO 菱形稳定性的启发，其具有较短的 Be-Be 距离但没有直接的金属-金属键，我们研究了类似的 MM'O（M、M' = Be、Mg、Ca）团簇中键合相互作用的本质。CCSD/cc-pVTZ 和 CCSD(T)/cc-pVQZ 计算等被用于确定 MM'O 团簇分裂为金属氧化物单体的优化几何形状和离解能。用于研究化学键的主要工具是域平均费米空穴的分析，包括局域自然轨道的生成和适当的二中心和三中心键指数的计算。这些各种分析得出的见解与 MO 菱形团簇的早期研究一致，即在 MM'O 环中未观察到直接的金属-金属键，而在 MOM' 部分检测到弱三中心（3c）键。一般来说，这些混合的 MM'O 团簇表现出介于 MO 和 M'O 之间的特征，并且 M 和 M'原子之间的差异似乎对 3c MOM'键合的整体程度影响很小。
