Electron transfer reactivity of O2+O2? system in low-spin coupling:Ab Initio study at electron correlation level

✍ Scribed by Bu, Yuxiang; Sun, Haitao; Niu, Hongbo

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 203 KB
• Volume: 20
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/(sici)1096-987x(19990730)20:10<989::aid-jcc1>3.0.co;2-e

✦ Synopsis

The electron transfer reactivity of the O q O y system in low-spin 2 2 Ž . coupling is studied at the second-order unrestricted Møller᎐Plesset full r 6-311 q G* basis set level by using different transition state structures. The properties and stabilities of the encounter complexes are compared for the five selected coupling structures: two T type, collinear, parallel, and crossing. The activation barriers and the coupling matrix elements are also calculated. The results indicate that the structures of the encounter complexes directly affect the electron transfer mechanism and rate. These encounter complexes are structurally unstable, the contact distances between the acceptor O and the donor O y are 2 2 generally large, the interaction is weak, and the structures are floppy. The electronic transmission factor for the reacting system, O q O y , is less than 2 2 unity; thus, the electron transfer reaction is nonadiabatic in nature. Analysis of the dependence of relevant kinetic parameters on various influencing factors has shown that the effect of the solvent medium on the coupling matrix element is small but that on the electron transfer rate is very large. Among the five selected transition state structures, the electron transfer is more likely to take place via T -type and P-type structures. In the low-spin coupling the favorable electronic 1 1 q Ž . 2 Ž y . 3 y Ž . states for two reacting species are Ý O and X ⌸ O instead of X Ý O g 2 g 2 g 2 2 Ž y . Ž . and X O , which are favorable for the high-spin quartet state coupling g 2 mechanism.