Leitão Ezequiel F V, Ventura Elizete, de Souza Miguel A F, Riveros José M, do Monte Silmar A
Departamento de Química Universidade Federal da ParaíbaJoão Pessoa, PB 58.059-900 Brazil.
Instituto de Química Universidade Federal do Rio Grande do Norte Natal, RN 59072-970 Brazil.
ChemistryOpen. 2017 Mar 23;6(3):360-363. doi: 10.1002/open.201600169. eCollection 2017 Jun.
The mechanism of the O and HO reaction (Haber-Weiss) under solvent-free conditions has been characterized at the DFT and CCSD(T) level of theory to account for the ease of this reaction in the gas phase and the formation of two different set of products (Blanksby et al., . , , 4948). The reaction is shown to proceed through an electron-transfer process from the superoxide anion to hydrogen peroxide, along two pathways. While the O + HO products are formed from a spin-allowed reaction (on the doublet surface), the preferred products, O(HO)+O, are formed through a spin-forbidden reaction as a result of a favorable crossing point between the doublet and quartet surface. Plausible reasons for the preference toward the latter set are given in terms of the characteristics of the minimum energy crossing point (MECP) and the stability of an intermediate formed (after the MECP) in the quartet surface. These unique results show that these two pathways are associated with a bifurcation, yielding spin-dependent products.
在无溶剂条件下，O与HO反应（哈伯-维西反应）的机理已在密度泛函理论（DFT）和耦合簇单双激发（CCSD(T)）理论水平上进行了表征，以解释该反应在气相中的易发性以及两种不同产物集的形成（布兰克斯比等人，……，4948）。结果表明，该反应沿着两条途径通过从超氧阴离子到过氧化氢的电子转移过程进行。虽然O + HO产物由自旋允许反应（在二重态表面上）形成，但由于二重态和四重态表面之间存在有利的交叉点，优选产物O(HO)+O通过自旋禁阻反应形成。根据最小能量交叉点（MECP）的特征以及在四重态表面形成的中间体（在MECP之后）的稳定性，给出了偏向后者产物集的合理原因。这些独特的结果表明，这两条途径与一个分岔相关，产生自旋相关的产物。
