In this project in the Inorganic, Bioinorganic, and Organometallic Program of the Chemistry Division, Meyer will continue fundamental studies of the photochemistry of transition metal complexes. This work may provide a framework by which our understanding of natural processes such as photosynthesis will be enhanced. The principal goal of the work is to gain insights into the fundamental details of how electron and energy transfer occur following MLCT excitation and how they can be controlled by synthetic design. Studies of electron transfer in the inverted region, including a detailed study of temperature and medium effects, will be continued. New intramolecular redox systems will be prepared which contain a variety of both electron transfer donors and acceptors. A systematic study of the redox separated states formed by the photolysis of these complexes will be directed toward the goal of maximizing quantum efficiencies and lifetimes. Chemical systems will be assembled that feature intramolecular time delays, in which the interconversion of two states is mediated by a third, higher energy state. A final goal is the preparation of a family of extended, ligand-bridged complexes which will provide a means for studying electron transfer over very long distances.