Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) , Campus UAB, 08193 Bellaterra, Spain.
J Phys Chem A. 2015 Jan 8;119(1):183-94. doi: 10.1021/jp510198g. Epub 2014 Dec 26.
A theoretical study of anionic complexes formed by two partly deprotonated oxoacids joined by hydrogen bonds has been carried out at the MP2 computational level. In spite of the ionic repulsion, local energy minima are found both in the gas phase and in aqueous solution. Electrostatic potential and electron density topologies, and the comparison with neutral complexes formed by oxoacids, reveal that the ionization has no significant effect on the properties of the hydrogen bonds. The stability of the complexes in the gas phase is explained by attractive forces localized in a volume situated in the hydrogen bond and defined as the electrostatic attraction region (EAR) and determined by the topological analyses of the electron density and the electrostatic potential, and by the electric field lines. In solution, the strong anionic repulsion is mostly screened by the effect of the surrounding polar solvent, which only leads to a weak destabilizing interaction in the hydrogen bond region and finally favors the overall stability of the complexes. The anion-anion complexes have been compared with the corresponding neutral ones (as salts or protonated forms), showing that EAR remains unchanged along the series.
氢键连接的两个部分去质子化的含氧酸阴离子配合物的理论研究在 MP2 计算水平上进行。尽管存在离子排斥，但在气相和水溶液中都发现了局部能量最小值。静电势和电子密度拓扑结构，以及与含氧酸形成的中性配合物的比较表明，电离对氢键的性质没有显著影响。配合物在气相中的稳定性可以通过局部在氢键所在的体积内的吸引力来解释，这个体积被定义为静电吸引区域（EAR），并通过电子密度和静电势的拓扑分析以及电场线来确定。在溶液中，强烈的阴离子排斥主要被周围极性溶剂的作用屏蔽，这只导致氢键区域的弱去稳定相互作用，并最终有利于配合物的整体稳定性。阴离子-阴离子配合物与相应的中性配合物（作为盐或质子化形式）进行了比较，结果表明 EAR 在整个系列中保持不变。
