IQTCUB, Departament de Química Física, Universitat de Barcelona, Barcelona, Spain.
J Phys Chem A. 2009 Dec 31;113(52):14741-8. doi: 10.1021/jp904852x.
The present investigation on some ternary M(+)-benzene-X(-) aggregates follows previous studies concerning the binary, M(+)-benzene (M = Li, Na, K, Rb, Cs) and X(-)-benzene (X = F, Cl, Br, I), systems. A semimepirical model describing the intermolecular potential energy, formulated as a combination of few leading effective components, is here extended and applied to investigate more complex systems. The balancing of size repulsion with induction and dispersion attraction is described as a combination of ion-bond interactions and an electrostatic component, rationalized on the basis of the benzene quadrupole moment, is also included. For M(+)-benzene-X(-) aggregates, the simultaneous presence of a cation and an anion close to the pi system originates a strong Coulombic attraction and nonadditivity effects of the induction energy, which are carefully considered and explicitly included to obtain a proper analytical functional representation of the ternary compound. The proposed semiempirical methodology, providing the whole potential energy surface in a convenient analytical form, is useful to predict the main features of stable and unstable configurations, saddle points, and energy barriers, allowing for investigation of their influence on molecular dynamics simulations.
本研究是在前人对二元 M(+)-苯-X(-)（M = Li、Na、K、Rb、Cs，X = F、Cl、Br、I）体系研究的基础上进行的。本文将一个描述分子间势能的半经验模型扩展并应用于更复杂的体系，该模型由少数主要有效成分组合而成。通过将尺寸排斥与诱导和色散吸引力平衡，模型中还包括了离子键相互作用和静电分量的组合，这是基于苯的四极矩来合理化的。对于 M(+)-苯-X(-) 聚集体，阳离子和阴离子同时靠近π体系会产生强烈的库仑吸引力和诱导能的非加性效应，这些效应都被仔细考虑并明确包含在内，以获得三元化合物的适当分析函数表示。所提出的半经验方法提供了方便的分析形式的整个势能表面，可用于预测稳定和不稳定构型、鞍点和能垒的主要特征，从而研究它们对分子动力学模拟的影响。
