Publication
603
Chem. Phys. ,324, 40-56, 2006.
DOI: 10.1016/j.chemphys.2005.09.029
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Electron transfer and bond breaking: Recent advances
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Cyrille Costentin,, Marc Roberrt , and Jean-Michel Savéant*
Contribution from the Laboratoire d'Electrochimie Moléculaire, Université de Paris 7-Denis Diderot, 2 place Jussieu,75251 Paris Cedex 05, France
After a reminder of concerted/stepwise mechanistic dichotomy and other basic
concepts and facts in the field, a series of recent advances is discussed.
Particular emphasis is laid on the interactions between the fragments formed
upon bond cleavage. These interactions may persist even in polar solvents and
have important consequences on dissociative electron transfer kinetics and on
the competition between concerted and stepwise pathways. Cleavage of ion
radicals and its reverse reaction are examples of single electron transfer
reactions concerted with bond cleavage and bond formation, respectively. The
case of aromatic carbon–heteroatom bonds is particularly worth examination since
symmetry restrictions impose circumventing a conical intersection. Reductive
dehalogenases are involved in ‘dehalorespiration' of anaerobic bacteria in which
the role of dioxygen in aerobic organisms is played by major polychloride
pollutants such as tetrachloroethylene. They offer an interesting illustration
of how the coupling of electron transfer with bond breaking may be an important
issue in natural processes. Applications of dissociative electron transfer
concepts and models to mechanistic analysis in this class of enzymes will be
discussed. |
