Molecular Modeling Group, Organic Chemical Sciences, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500 607, AP, India.
J Phys Chem B. 2011 Feb 3;115(4):703-10. doi: 10.1021/jp109749a. Epub 2010 Dec 14.
Ab initio and density functional theory calculations are performed on half-sandwich (M-Cp) and sandwich (Cp-M-Cp) complexes of alkali and alkaline earth metals (M = Li, Na, K, Mg, and Ca) with cyclopentadienyl ligand (Cp). A comparison of dissociation energies demonstrates the ease of dissociation of the complex as ions in solvent phase and preference for dissociation as radicals in gas phase. Atoms in molecules analysis is used to characterize this cation-π interaction based on electron density values obtained at the cage critical point. The contribution of various components to the complex energy is estimated using reduced variational space analysis confirming maximum contribution from the coulomb exchange followed by contributions from polarization and charge transfer components of cyclopentadienyl ligand.
采用从头算和密度泛函理论对碱金属和碱土金属（M = Li、Na、K、Mg 和 Ca）与环戊二烯基配体（Cp）的半夹心（M-Cp）和夹心（Cp-M-Cp）配合物进行了计算。解离能的比较表明，在溶剂相中，配合物易于离解为离子，而在气相中则易于离解为自由基。分子中的原子分析用于基于在笼状临界点处获得的电子密度值来表征这种阳离子-π相互作用。使用简化变分空间分析估计了各种组分对配合物能量的贡献，证实了库仑交换的最大贡献，其次是环戊二烯基配体的极化和电荷转移分量的贡献。
