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Electron transfer reactivity of O 2 +O 2 − system in low‐spin coupling: Ab Initio study at electron correlation level
Author(s) -
Bu Yuxiang,
Sun Haitao,
Niu Hongbo
Publication year - 1999
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/(sici)1096-987x(19990730)20:10<989::aid-jcc1>3.0.co;2-e
Subject(s) - chemistry , electron transfer , reactivity (psychology) , coupling (piping) , ab initio , electron , atomic physics , matrix (chemical analysis) , electronic structure , ab initio quantum chemistry methods , computational chemistry , chemical physics , molecular physics , molecule , physics , materials science , quantum mechanics , medicine , alternative medicine , organic chemistry , pathology , chromatography , metallurgy
The electron transfer reactivity of the O 2 +O 2 −system in low‐spin coupling is studied at the second‐order unrestricted Møller–Plesset (full)/6‐311+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 2 and the donor O 2 −are generally large, the interaction is weak, and the structures are floppy. The electronic transmission factor for the reacting system, O 2 +O 2 − , is less than 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 1 ‐type and P ‐type structures. In the low‐spin coupling the favorable electronic states for two reacting species are 1 ∑ g + (O 2 ) and X 2 Π g (O 2 − ) instead of X 3 ∑ g − (O 2 ) and X 2 π g (O 2 − ), which are favorable for the high‐spin (quartet state) coupling mechanism. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 989–998, 1999