Cabaleiro-Lago Enrique M, Rodríguez-Otero Jesús, Peña-Gallego Angeles
Departamento de Quimica Fisica, Facultade de Ciencias, Universidade de Santiago de Compostela, Campus de Lugo, Avda Alfonso X El Sabio 27002 Lugo, Galicia, Spain.
J Phys Chem A. 2008 Jul 17;112(28):6344-50. doi: 10.1021/jp8021979. Epub 2008 Jun 21.
The characteristics of the interaction between the pi cloud of naphthalene and up to two H2O or H2S molecules were studied. Calculations show that clusters formed by naphthalene and one H2O or H2S molecule have similar geometric features, and also present similar interaction energies. Our best estimates for the interaction energy amount to -2.95 and -2.92 kcal/mol for H2O and H2S, respectively, as obtained with the CCSD(T) method. Calculations at the MP2 level employing large basis sets should be avoided because they produce highly overestimated interaction energies, especially for hydrogen sulfide complexes. The MPWB1K functional, however, provides values pretty similar to those obtained with the CCSD(T) method. Although the magnitude of the interaction is similar with both H2X molecules, its nature is somewhat different: the H2O complex presents electrostatic and dispersion contributions of similar magnitude, whereas for H2S the interaction is dominated by dispersion. In clusters containing two H2X molecules several minima were characterized. In water clusters, the total interaction energy is dominated by the presence of a O-H...O hydrogen bond and, as a consequence, structures where this contact is present are the most stable. However, clusters containing H2S show structures with no interaction between H2S moieties which are as stable as the hydrogen bonded ones, because they allow an optimal H2S...naphthalene interaction, which is stronger than the S-H...S contact. Therefore it is possible that in larger polycycles hydrogen sulfide molecules will be spread onto the surface maximizing S-H...pi interactions rather than aggregated, forming H2S clusters.
研究了萘的π电子云与至多两个H₂O或H₂S分子之间相互作用的特征。计算表明，由萘与一个H₂O或H₂S分子形成的团簇具有相似的几何特征，并且呈现出相似的相互作用能。使用CCSD(T)方法得到的H₂O和H₂S相互作用能的最佳估计值分别为-2.95和-2.92 kcal/mol。应避免使用大基组在MP2水平上进行计算，因为它们会产生高度高估的相互作用能，特别是对于硫化氢配合物。然而，MPWB1K泛函提供的值与用CCSD(T)方法得到的值非常相似。尽管与两个H₂X分子的相互作用强度相似，但其性质有所不同：H₂O配合物呈现出大小相似的静电和色散贡献，而对于H₂S，相互作用主要由色散主导。在含有两个H₂X分子的团簇中，表征了几个极小值。在水团簇中，总相互作用能由O-H...O氢键的存在主导，因此，存在这种接触的结构是最稳定的。然而，含有H₂S的团簇显示出H₂S部分之间没有相互作用的结构，这些结构与氢键结构一样稳定，因为它们允许最佳的H₂S...萘相互作用，这种相互作用比S-H...S接触更强。因此，在更大的多环中，硫化氢分子有可能扩散到表面，使S-H...π相互作用最大化，而不是聚集形成H₂S团簇。
