Matito Eduard, Poater Jordi, Bickelhaupt F Matthias, Solà Miquel
Institut de Química Computacional and Departament de Química, Universitat de Girona, 17071 Girona, Catalonia, Spain.
J Phys Chem B. 2006 Apr 13;110(14):7189-98. doi: 10.1021/jp057517n.
The chemical bonding in methylalkalimetals (CH(3)M)(n)() (M = Li-K; n = 1, 4) has been investigated by making use of topological analyses grounded in the theory of atoms in molecules (AIM) and in the electron localization function (ELF). Both analyses describe the C-M bond as an ionic interaction. However, while AIM diagnoses a decrease of ionicity with tetramerization, ELF considers tetramers more ionic. Divergences emerge also when dealing with the bonding topology given by each technique. For the methylalkalimetal tetramers, the ELF analysis shows that each methyl carbon atom interacts through a bond pair with each of the three hydrogen atoms belonging to the same methyl group and through an ionic bond with the triangular face of the tetrahedral metal cluster in front of which the methyl group is located. On the other hand, the AIM topological description escapes from the traditional bonding schemes, presenting hypervalent carbon and alkalimetal atoms. Our results illustrate that fundamental concepts, such as that of the chemical bond, have a different, even colliding meaning in AIM and ELF theories.
通过基于分子中原子理论（AIM）和电子定位函数（ELF）的拓扑分析，对甲基碱金属（CH(3)M）(n)（M = Li - K；n = 1, 4）中的化学键进行了研究。两种分析都将C - M键描述为离子相互作用。然而，虽然AIM诊断出随着四聚化离子性降低，但ELF认为四聚体的离子性更强。在处理每种技术给出的键合拓扑时也会出现分歧。对于甲基碱金属四聚体，ELF分析表明，每个甲基碳原子通过一个键对与属于同一甲基的三个氢原子中的每一个相互作用，并通过离子键与甲基所在四面体金属簇的三角形面相互作用。另一方面，AIM拓扑描述偏离了传统的键合方案，呈现出超价碳和碱金属原子。我们的结果表明，诸如化学键这样的基本概念在AIM和ELF理论中有不同的，甚至相互冲突的含义。
