ABSTRACT
There are well over one million known organic molecules, not counting macromolecules such as proteins. Quite a few are useful as participants in electron transfer (ET) or excitation energy transfer (EET) reactions. The ET rate difference between otherwise quite similar molecules varies over several orders of magnitude. In the case of ET between transition metal complexes, the variation in rate spans over more than 10 orders of magnitude. These differences are due to variation in structure when the electrons or excitations are given off or received. The less the structural change, the faster is the reaction.
