Relation between the rate of
outer-sphere electron transfer and the thermodynamics of this process. Essentially, the
rate constant within the
encounter complex (or the
rate constant of
intramolecular transfer) is given by the Eyring equation:
where
is the
Boltzmann constant,
the
Planck constant,
the
gas constant and
the so-called electronic
transmission factor
(
for
adiabatic and
for
diabatic electron transfer). For
outer-sphere electron transfer the barrier height can be expressed as:
where
is the standard Gibbs energy change accompanying the electron-transfer reaction and
the total reorganization energy.
Note:
Whereas the classical Marcus equation has been found to be quite adequate in the normal
region, it is now generally accepted that in the inverted region a more elaborate
formulation, taking into account explicitly the Franck–Condon factor due to quantum
mechanical vibration modes, should be employed.
Source:
PAC, 2007, 79, 293
(Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006))
on page 368
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
https://doi.org/10.1351/goldbook.
