• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Is the HO _4 ~- anion a key species in the aqueous-phase decomposition of ozone?
【24h】

Is the HO _4 ~- anion a key species in the aqueous-phase decomposition of ozone?

机译：HO _ 4-阴离子是臭氧水相分解中的关键物质吗？

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The role of the HO _4 ~- anion in atmospheric chemistry and biology is a matter of debate, because it can be formed from, or be in equilibrium with, key species such as O _3 + HO ~- or HO _2 + _O 2 ~-. The determination of the stability of HO _4 ~- in water therefore has the greatest relevance for better understanding the mechanism associated with oxidative cascades in aqueous solution. However, experiments are difficult to perform because of the short-lived character of this species, and in this work we have employed DFT, CCSD(T) complete basis set (CBS), MRCI/aug-cc-pVTZ, and combined quantum mechanics/molecular mechanics (QM/MM) calculations to investigate this topic. We show that the HO _4 ~- anion has a planar structure in the gas phase, with a very large HOO-OO bond length (1.823 ?). In contrast, HO _4 ~- adopts a nonplanar configuration in aqueous solution, with huge geometrical changes (up to 0.232 ? for the HOO-OO bond length) with a very small energy cost. The formation of the HO _4 ~- anion is predicted to be endergonic by 5.53±1.44 and 2.14±0.37 kcal mol ~(-1) with respect to the O _3 + HO ~- and HO _2 + O _2 - channels, respectively. Moreover, the combination of theoretical calculations with experimental free energies of solvation has allowed us to obtain accurate free energies for the main reactions involved in the aqueous decomposition of ozone. Thus, the oxygen transfer reaction (O _3 + OH ~- → HO _2 + O _2 ~-) is endergonic by 3.39±1.80 kcal mol ~(-1), the electron transfer process (O _3 + O _2 ~- → O _3 ~- + O _2) is exergonic by 31.53±1.05 kcal mol ~(-1), supporting the chain-carrier role of the superoxide ion, and the reaction O _3 + HO _2 - → OH + O _2 ~- + O _2 is exergonic by 12.78±1.15 kcal mol ~(-1), which is consistent with the fact that the addition of small amounts of HO _2 ~- (through H _2O _2) accelerates ozone decomposition in water. The combination of our results with previously reported thermokinetic data provides some insights into the potentially important role of the HO _4 ~- anion as a key reaction intermediate.
机译：HO _4〜-阴离子在大气化学和生物学中的作用尚有争议，因为它可以由诸如O _3 + HO〜-或HO _2 + _O 2〜的关键物种形成或与之平衡。 -因此，为了更好地理解与水溶液中氧化级联反应有关的机理，确定HO_4〜-在水中的稳定性具有最大的意义。但是，由于该物种的生命周期短，因此很难进行实验，在这项工作中，我们采用了DFT，CCSD（T）完整基集（CBS），MRCI / aug-cc-pVTZ和组合量子力学/分子力学（QM / MM）计算以研究此主题。我们表明，HO _4〜-阴离子在气相中具有平面结构，具有非常大的HOO-OO键长（1.823？）。相反，HO _4〜-在水溶液中采用非平面构型，具有巨大的几何变化（HOO-OO键长高达0.232？），并且能源成本非常低。相对于O _3 + HO〜-和HO _2 + O _2-通道，HO _4〜-阴离子的形成被预测分别为5.53±1.44和2.14±0.37 kcal mol〜（-1）。此外，理论计算与溶剂化的实验自由能的结合使我们能够获得与臭氧水分解有关的主要反应的准确自由能。因此，氧转移反应（O _3 + OH〜-→HO _2 + O _2〜-）以3.39±1.80 kcal mol〜（-1）呈正电子，电子转移过程（O _3 + O _2〜-→O _3〜-+ O _2）的运动强度为31.53±1.05 kcal mol〜（-1），支持超氧离子的链-载体作用，并且反应O _3 + HO _2-→OH + O _2〜-+ O _2的运动能级为12.78±1.15 kcal mol〜（-1），这与以下事实一致：添加少量的HO _2〜-（通过H _2O _2）会加速水中的臭氧分解。我们的结果与先前报道的热动力学数据的结合，为HO_4〜-阴离子作为关键反应中间体的潜在重要作用提供了一些见识。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号