Amaro-Estrada J I, Maron L, Ramírez-Solís A
Departamento de Física, Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Cuernavaca, Morelos 62209, México.
Phys Chem Chem Phys. 2014 May 14;16(18):8455-64. doi: 10.1039/c3cp55339f.
We address the aqueous solvation of HgClOH through a systematic study of stepwise hydration considering the HgClOH-(H2O)n structures with n = 1-24. After calibration of the DFT method, the electronic calculations have been carried out using the B3PW91 exchange-correlation functional. For n < 5 the main geometrical parameters and incremental binding energies are in agreement with counterpoise-corrected MP2/AVTZ static values and BO-MP2 dynamic averages. For n > 15 three direct water-Hg interactions appear during the hydration process and a pentacoordinated trigonal bipyramid apical pattern around Hg is found. 22 water molecules are needed to build the first solvation shell. Unlike microsolvated HgCl2, no stable equatorial trigonal bipyramid was found. Optimizations with the Polarizable Continuum Model lead to structures with extremely large Hg-O(water) distances because of a dominant solvation effect on the explicit water molecules; however, this overestimation diminishes for large values of n. A DFT Born-Oppenheimer molecular dynamics simulation at T = 700 K revealed the stability of the HgClOH-(H2O)24 complex with an average trigonal bipyramid Hg-coordination pattern, in accordance with the static cluster description. After thermalization is achieved, the exchange rate of the Hg-coordinated water molecules is estimated to be ca. 10(11) s(-1).
我们通过对HgClOH-(H₂O)ₙ（n = 1 - 24）结构的逐步水合作用进行系统研究，探讨了HgClOH的水相溶剂化作用。在对密度泛函理论（DFT）方法进行校准后，使用B3PW91交换相关泛函进行了电子计算。对于n < 5，主要几何参数和增量结合能与经counterpoise校正的MP2/AVTZ静态值以及BO-MP2动态平均值一致。对于n > 15，在水合过程中出现了三种直接的水 - Hg相互作用，并且发现Hg周围存在五配位三角双锥顶模式。构建第一个溶剂化壳层需要22个水分子。与微溶剂化的HgCl₂不同，未发现稳定的赤道三角双锥。使用极化连续介质模型进行的优化导致结构具有极大的Hg - O(水)距离，这是由于对显式水分子的主导溶剂化效应；然而，对于较大的n值，这种高估会减小。在T = 700 K下进行的DFT玻恩 - 奥本海默分子动力学模拟揭示了HgClOH-(H₂O)₂₄配合物的稳定性，其具有平均三角双锥Hg配位模式，这与静态簇描述一致。在达到热化后，Hg配位水分子的交换速率估计约为10¹¹ s⁻¹。
