Electronic Relaxation Contributions to Electron Transfer Reactivity: Application to Rubredoxins

P. Kennepohl,1 E. I. Solomon2

1Division of Chemistry and Chemical Engineering, California Institute of Technology
2Department of Chemistry, Stanford University


Photoelectron spectroscopy is developed as a method to experimentally evaluate electronic relaxation, the electronic changes that occur on redox. This method is applied to [Fe(SPh)4]2- and the results are used to define the origin of the electronic structure changes that occur on redox. Results from this analysis are related to the electron transfer properties of Rubredoxins (Rd), a well-known electron transport protein with an [Fe(SCys)4]2-,1- active site. The contributions of electronic relaxation to redox properties are evaluated with respect to its influence on the reduction potential (E0), inner-sphere reorganization energy (li), and electronic coupling matrix element (HDA) for electron self-exchange in Rd. The effects of electronic relaxation are found to be very large and should not be neglected in analyses of electron transfer reactivity of such active sites.



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