Monjaraz-Rodríguez Alejandra, Rodriguez-Bautista Mariano, Garza Jorge, Zubillaga Rafael A, Vargas Rubicelia
Departamento de Química, División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, A.P. 55-534, C. P. 09340, Ciudad de México, Mexico.
J Mol Model. 2018 Jul 2;24(7):187. doi: 10.1007/s00894-018-3725-5.
The potential energy surface of [Cu(HO)] clusters with n = 12, 16, and 18 was explored by using a modified version of the simulated annealing method. Such exploration was carried out by using the PM7 semiempirical method to obtain around 100,000 isomers, which provide candidates to be optimized with PBE0-D3, M06-2X, and BHLYP exchange-correlation functionals coupled with the 6-311++G** basis set. These methods based on the Kohn-Sham approach delivered isomers with coordination numbers of 4, 5, and 6. The analysis used to obtain coordination numbers was based on geometrical parameters and the quantum theory of atoms in molecules (QTAIM) approach. Our methodology found only one isomer with fourfold coordination and its probabilities to appear in these clusters are quite small for high temperatures. The procedure used in this article predicts important populations of fivefold and sixfold coordination clusters, in fact, the fivefold coordination dominates for PBE0-D3 and BHLYP methods, although the sixfold coordination starts to be important when the number of water molecules is increased. The nature of axial and equatorial contacts is discussed in the context of the QTAIM and the noncovalent interaction index (NCI), which gives a clear classification of such orientations. Also, these methods suggest a partial covalent interaction between the Cu and water molecules in both positions; equatorial and axial.
采用模拟退火方法的改进版本，对n = 12、16和18的[Cu(HO)]团簇的势能面进行了探索。通过使用PM7半经验方法进行这种探索，以获得约100,000个异构体，这些异构体为使用PBE0-D3、M06-2X和BHLYP交换相关泛函与6-311++G**基组进行优化提供了候选物。这些基于Kohn-Sham方法的方法给出了配位数为4、5和6的异构体。用于获得配位数的分析基于几何参数和分子中原子的量子理论（QTAIM）方法。我们的方法仅发现了一种具有四重配位的异构体，并且在高温下其在这些团簇中出现的概率相当小。本文中使用的程序预测了大量的五重和六重配位团簇，事实上，对于PBE0-D3和BHLYP方法，五重配位占主导，尽管当水分子数量增加时六重配位开始变得重要。在QTAIM和非共价相互作用指数（NCI）的背景下讨论了轴向和赤道接触的性质，这给出了此类取向的清晰分类。此外，这些方法表明在赤道和轴向两个位置的Cu与水分子之间存在部分共价相互作用。
