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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Effect of substituents on the preferred modes of one-electron reductive cleavage of N-Cl and N-Br bonds
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Effect of substituents on the preferred modes of one-electron reductive cleavage of N-Cl and N-Br bonds

机译：取代基对N-Cl和N-Br键单电子还原裂解的优选方式的影响

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In this study, we investigate the effect of substituents in determining the modes of one-electron reductive cleavage of X-NRR′ (X = Cl and Br) molecules. We achieve this through comparison of the calculated gas-phase electron affinities (EAs) and aqueous-phase one-electron reduction potentials (E 's) for a range of nitrogen-centered radicals (?NRR′) with the corresponding EA and E values for ?Cl and ?Br. The gas-phase EAs have been obtained using the benchmark-quality W1w thermochemical protocol, whereas E values have been obtained by additionally applying free energy of solvation corrections, obtained using the conductor-like polarizable continuum (CPCM) model. We find that the N-halogenated derivatives of amines and amides should generally cleave in such a way as to afford ?NRR′ and X-. For the N-halogenated imides, on the other hand, the N-brominated derivatives are predicted to produce ?Br in solution, whereas the N-chlorinated derivatives again would give Cl-. Importantly, we predict that N-bromouracil is likely to afford ?Br. This may have important implications in terms of inflammatory-related diseases, because ?Br may damage biomolecules such as proteins and DNA. To assist in the determination of the gas-phase EAs of larger ?NRR′ radicals, not amenable to investigation using W1w, we have evaluated the performance of a wide range of lower-cost theoretical methods. Of the standard density functional theory (DFT) procedures, M06-2X, τ-HCTHh, and B3-LYP show good performance, with mean absolute deviations (MADs) from W1w of 4.8-6.8 kJ mol~(-1), whereas ROB2-PLYP and B2-PLYP emerge as the best of the double-hybrid DFTs (DHDFTs), with MADs of 2.5 and 3.0 kJ mol~(-1), respectively. Of the Gn-type procedures, G3X and G4 show very good performance (MADs = 2.4 and 2.6 kJ mol~(-1), respectively). The G4(MP2)-6X+ procedure performs comparably, with an MAD of 2.7 kJ mol~(-1), with the added advantage of significantly reduced computational expense.
机译：在这项研究中，我们研究了取代基在确定X-NRR'（X = Cl和Br）分子的单电子还原裂解方式中的作用。我们通过比较一系列以氮为中心的自由基（ΔNRR'）的计算出的气相电子亲和力（EAs）和水相单电子还原势（E's）以及相应的EA和E值来实现这一点用于？Cl和？Br。气相EA是使用基准质量W1w热化学方案获得的，而E值是通过额外应用溶剂化校正的自由能获得的，该溶剂化校正是使用类似导体的可极化连续体（CPCM）模型获得的。我们发现，胺和酰胺的N-卤代衍生物通常应裂解成能提供ΔNRR′和X-的方式。另一方面，对于N-卤代的酰亚胺，预计N-溴化的衍生物在溶液中会产生？Br，而N-氯化的衍生物又会产生Cl-。重要的是，我们预测N-溴尿嘧啶可能负担得起？Br。这可能在炎症相关疾病方面具有重要意义，因为？Br可能会破坏蛋白质和DNA等生物分子。为了帮助确定较大的？NRR'自由基的气相EA，而这不适合使用W1w进行研究，我们评估了各种低成本理论方法的性能。在标准密度泛函理论（DFT）程序中，M06-2X，τ-HCTHh和B3-LYP具有良好的性能，与W1w的平均绝对偏差（MAD）为4.8-6.8 kJ mol〜（-1），而ROB2 -PLYP和B2-PLYP成为双杂交DFT（DHDFTs）中的佼佼者，MAD分别为2.5和3.0 kJ mol〜（-1）。在Gn型程序中，G3X和G4具有非常好的性能（MAD分别为2.4和2.6 kJ mol〜（-1））。 G4（MP2）-6X +程序的性能相当，MAD为2.7 kJ mol〜（-1），具有显着减少计算费用的优点。

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