QM/MM kinetic isotope effects for chloromethane hydrolysis in water
QM/MM kinetic isotope effects for chloromethane hydrolysis in water
复制标题
QM/MM 动力学同位素对水中氯甲烷水解的影响
DOI：
10.1002/poc.3144
复制
发表时间：
2013
影响因子：
1.8
通讯作者：
Javier Ruiz Pernía J
中科院分区：
文献类型：
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作者：
Javier Ruiz Pernía J
氯甲烷水解的计算模拟已经使用混合量子力学/分子力学方法与大量水分子的显式溶剂化进行。在论文的第一部分中，我们给出了298 K下2° 2 H3，1° 14 C和1° 37 Cl的动力学同位素效应（KIE）的结果，采用AM 1/TIP 3 P和B3 LYP/6 - 31 G * QM方法，和亲核试剂H2O和亲电试剂CH 3Cl被496个溶剂化TIP 3 P水分子包围。通过连续删除行和列，减小了为包括多达104 MM水分子的该系统的子集计算的初始Hessian的大小，并且对每个KIE进行了评估。我们建议，在溶剂化体系中的KIE的准确计算应涉及一个子集海森，包括基板连同任何溶剂原子，使特定的相互作用与任何同位素取代的原子。在论文的第二部分中，用B3 LYP/6 - 31+G（d，p）/TIP 3 P方法计算的系综平均2° α-2 H3 KIE与实验结果符合得很好。这种比较是有意义的，因为它包括考虑由于一系列代表性的热可及溶剂配置的采样的不确定性。我们还提出了系综平均的14 C和37 Cl KIE，这些KIE还没有被实验确定。版权所有© 2013约翰威利父子有限公司.
Computational simulations for chloromethane hydrolysis have been performed using hybrid quantum‐mechanical/molecular‐mechanical methods with explicit solvation by large numbers of water molecules. In the first part of the paper, we present results for 2°2H3, 1°14C, and 1°37Cl kinetic isotope effects (KIEs) at 298 K with both the AM1/TIP3P and B3LYP/6‐31G* QM methods for the nucleophile H2O and electrophile CH3Cl surrounded by 496 solvating TIP3P water molecules. An initial Hessian computed for a subset of this system including up to 104 MM water molecules was reduced in size by successive deletion of rows and columns, and KIEs were evaluated for each. We suggest that accurate calculations of KIEs in solvated systems should involve a subset Hessian including the substrate together with any solvent atoms making specific interactions with any isotopically substituted atom. In the second part of the paper, the ensemble‐averaged 2° α‐2H3KIE calculated with the B3LYP/6‐31+G(d,p)/TIP3P method is shown to be in good agreement with experiment. This comparison is meaningful because it includes consideration of uncertainties owing to sampling of a range of representative thermally accessible solvent configurations. We also present ensemble‐averaged14C and37Cl KIEs which have not as yet been determined experimentally. Copyright © 2013 John Wiley & Sons, Ltd.