Calculation of one-electron redox potentials revisited. Is it possible to calculate accurate potentials with density functional methods?
Calculation of one-electron redox potentials revisited. Is it possible to calculate accurate potentials with density functional methods?
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DOI：
10.1021/jp811388w
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发表时间：
2009-05
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影响因子：
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通讯作者：
L. Roy;E. Jakubikova;M. Guthrie;E. Batista
中科院分区：
文献类型：
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作者：
L. Roy;E. Jakubikova;M. Guthrie;E. Batista
用密度泛函方法计算了二茂铁的单电子氧化势和第一、二、三排元素的一系列小过渡金属化合物的氧化还原电偶。溶剂化效应通过自洽反应场(SCRF)结合，使用极化连续介质模型(PCM)。通过对七种不同密度泛函和三种不同基组的研究，我们发现没有一种密度泛函方法能够以实验的绝对标准氢电极(SHE)电势为参照，再现实验的氧化还原趋势。此外，包括额外的必要假设，如溶剂化效应，不会导致关于适当泛函的任何结论。然而，我们认为，如果一个人参考他们的过渡金属化合物的结果与计算的二茂铁的绝对半电池电势，他们可以绕过预测氧化还原电偶所必需的额外假设。将该方法应用于几种有机金属和无机络合物，得到了与实验值很好的相关性(R(2)=0.97)，使预测趋势成为可能。混合泛函B3LYP系统地低估了氧化还原电势；然而，当考虑基线位移时，密度泛函与实验之间的线性相关性很好(R(2)=0.96)。该协议是一个强大的工具，使理论化学家能够预测几种过渡金属络合物在溶液中的氧化还原电势，并有助于合理设计氧化还原活性催化剂。
Density Functional calculations have been performed to calculate the one-electron oxidation potential for ferrocene and the redox couples for a series of small transition metal compounds of the first-, second-, and third-row elements. The solvation effects are incorporated via a self-consistent reaction field (SCRF), using the polarized continuum model (PCM). From our study of seven different density functionals combined with three different basis sets for ferrocene, we find that no density functional method can reproduce the redox trends from experiment when referencing our results to the experimental absolute standard hydrogen electrode (SHE) potential. In addition, including additional necessary assumptions such as solvation effects does not lead to any conclusion regarding the appropriate functional. However, we propose that if one references their transition metal compounds results to the calculated absolute half-cell potential of ferrocene, they can circumvent the additional assumptions necessary to predict a redox couple. Upon employing this method on several organometallic and inorganic complexes, we obtained very good correlation between calculated and experimental values (R(2) = 0.97), making it possible to predict trends with a high level of confidence. The hybrid functional B3LYP systematically underestimates the redox potential; however, the linear correlation between DFT and experiment is good (R(2) = 0.96) when including a baseline shift. This protocol is a powerful tool that allows theoretical chemists to predict the redox potential in solution of several transition metal complexes a priori and aids in the rational design of redox-active catalysts.