Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København, ∅, Denmark.
Phys Chem Chem Phys. 2010 Oct 21;12(39):12833-9. doi: 10.1039/c0cp00383b. Epub 2010 Aug 27.
We have used different computational methods, including B3LYP, CCSD(T)-F12 and CBS-QB3, to study and compare the addition-elimination reaction of the nitrate radical NO(3) with four sulfur-containing species relevant to atmospheric chemistry: hydrogen sulfide (H(2)S), dimethyl sulfide [(CH(3))(2)S], dimethyl sulfoxide [(CH(3))(2)SO] and sulfur dioxide (SO(2)). We find that the reaction with (CH(3))(2)SO to give NO(2) + (CH(3))(2)SO(2) has a very low barrier, and is likely to be the dominant oxidation mechanism for (CH(3))(2)SO in the atmosphere. In agreement with previous experimental data and computational results, we find that the reaction with H(2)S and SO(2) is very slow, and the reaction with (CH(3))(2)S is not competitive with the hydrogen abstraction route. The differences in reaction energetics and rates between the four species are explained in terms of stabilizing interactions in the transition states and differences in sulfur-oxygen bond strengths.
我们使用了不同的计算方法，包括 B3LYP、CCSD(T)-F12 和 CBS-QB3，来研究和比较硝酸盐自由基 NO(3)与四种与大气化学有关的含硫物质的加成消除反应：硫化氢 (H(2)S)、二甲基硫 [(CH(3))(2)S]、二甲基亚砜 [(CH(3))(2)SO] 和二氧化硫 (SO(2))。我们发现，(CH(3))(2)SO 与 NO(3)反应生成 NO(2) + (CH(3))(2)SO(2) 的势垒非常低，这很可能是 (CH(3))(2)SO 在大气中的主要氧化机制。与之前的实验数据和计算结果一致，我们发现 H(2)S 和 SO(2)的反应非常缓慢，而 (CH(3))(2)S 的反应与氢提取途径不具有竞争关系。四种物质之间反应能量学和速率的差异可以用过渡态中的稳定相互作用和硫-氧键强度的差异来解释。
