Theory of Proton and Electron Transfer in Liquids

MARCUS THEORY OF PROTON AND ELECTRON TRANSFER IN LIQUIDS 

The Polanyi expressions relate the activation energy to the overall free energy difference for the reaction. 

In a liquid the molecules or ions interact strongly with each other. A liquid can be considered disordered on a long distance scale with respect to molecule-molecule distances. However, on a short-range, when one considers the interaction between nearest or next nearest neighbor atoms or molecules, a liquid shows order. This derives from the interaction potential between the particles. 

When two particles in a liquid interact, the rate expression becomes 

Herep(r) is the radial distribution function (i. e., the probability that the two particles are at a distance r) in the solution and W r) is their interaction potential. Additional effects have to be taken into account when reactions involving charge transfer occur. In section (5.1), it was mentioned that polar transition states become stabilized in polar liquids, i.e., liquids with a large dielectric constant. This derives from the reorientation of the liquid molecules in the field generated by the dipole of the polar transition state. The cost to separate the charges, produced upon ion formation, has become reduced. The equation for the electrostatic interaction between two charges is 

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