Núcleo de Estudos em Química Computacional, Departamento de Química, ICE, Universidade Federal de Juiz de Fora, Campus Universitário, 36.036-330 Juiz de Fora-Minas Gerais, Brazil.
J Comput Chem. 2012 Nov 5;33(29):2292-302. doi: 10.1002/jcc.23061. Epub 2012 Jul 10.
In this article, we conducted an extensive ab initio study on the importance of the level of theory and the basis set for theoretical predictions of the structure and reactivity of cisplatin [cis-diamminedichloroplatinum(II) (cDDP)]. Initially, the role of the basis set for the Pt atom was assessed using 24 different basis sets, including three all-electron basis sets (ABS). In addition, a modified all-electron double zeta polarized basis set (mDZP) was proposed by adding a set of diffuse d functions onto the existing DZP basis set. The energy barrier and the rate constant for the first chloride/water exchange ligand process, namely, the aquation reaction, were taken as benchmarks for which reliable experimental data are available. At the B3LYP/mDZP/6-31+G(d) level (the first basis set is for Pt and the last set is for all of the light atoms), the energy barrier was 22.8 kcal mol(-1), which is in agreement with the average experimental value, 22.9 ± 0.4 kcal mol(-1). For the other accessible ABS (DZP and ADZP), the corresponding values were 15.4 and 24.5 kcal mol(-1), respectively. The ADZP and mDZP are notably similar, raising the importance of diffuse d functions for the prediction of the kinetic properties of cDDP. In this article, we also analyze the ligand basis set and the level of theory effects by considering 36 basis sets at distinct levels of theory, namely, Hartree-Fock, MP2, and several DFT functionals. From a survey of the data, we recommend the mPW1PW91/mDZP/6-31+G(d) or B3PW91/mDZP/6-31+G(d) levels to describe the structure and reactivity of cDDP and its small derivatives. Conversely, for large molecules containing a cisplatin motif (for example, the cDDP-DNA complex), the lower levels B3LYP/LANL2DZ/6-31+G(d) and B3LYP/SBKJC-VDZ/6-31+G(d) are suggested. At these levels of theory, the predicted energy barrier was 26.0 and 25.9 kcal mol(-1), respectively, which is only 13% higher than the actual value.
本文对 cis-二氨二氯合铂(II)（顺铂，cDDP）的结构和反应性的理论预测中理论水平和基组的重要性进行了广泛的从头算研究。首先，我们使用 24 种不同的基组（包括 3 种全电子基组）评估了 Pt 原子基组的作用。此外，我们还通过在现有的 DZP 基组上添加一组弥散 d 函数，提出了一种改进的全电子双 zeta 极化基组（mDZP）。我们选择第一个氯/水配体交换过程（即水合反应）的能量势垒和速率常数作为基准，因为这些基准有可靠的实验数据。在 B3LYP/mDZP/6-31+G(d)水平（第一个基组是针对 Pt 的，最后一个基组是针对所有轻原子的）下，能量势垒为 22.8 kcal/mol，与平均实验值 22.9 ± 0.4 kcal/mol 一致。对于其他可访问的全电子基组（DZP 和 ADZP），相应的值分别为 15.4 和 24.5 kcal/mol。ADZP 和 mDZP 非常相似，这表明弥散 d 函数对 cDDP 动力学性质的预测很重要。在本文中，我们还通过考虑不同理论水平的 36 种基组来分析配体基组和理论水平的影响，这些基组包括 Hartree-Fock、MP2 和几种 DFT 泛函。通过对数据的调查，我们推荐使用 mPW1PW91/mDZP/6-31+G(d)或 B3PW91/mDZP/6-31+G(d)水平来描述 cDDP 及其小衍生物的结构和反应性。相反，对于含有顺铂结构的较大分子（例如，cDDP-DNA 复合物），建议使用较低的水平 B3LYP/LANL2DZ/6-31+G(d)和 B3LYP/SBKJC-VDZ/6-31+G(d)。在这些理论水平下，预测的能量势垒分别为 26.0 和 25.9 kcal/mol，仅比实际值高 13%。
