In this project in the Inorganic, Bioinorganic, and Organometallic Program of the Chemistry Division, Dr. Harry B. Gray of California Institute of Technology will conduct systematic studies on long-range electron transfer between an iridium core and pyridinium acceptors connected to the core by rigid spacers. The spacers will be built from both saturated and unsaturated carbon units. The work is expected to yield fundamental information that will be helpful in developing molecular approaches to solar energy conversion and information storage. Extensive measurements of electron transfer rates through various rigid spacers will enable the relationships betweenelectronic coupling and spacer length and electronic structure to be determined. The iridium core consists of an Iridium (I) dimer, which serves as the electron donor. The acceptors are N-alkylpyridinium groups bound to phosphinite ligands in the molecule selected for study. The iridium atoms are bridged by 3,5-dimethylpyrazolyl and are also bound to carbonyl ligands. This molecule contains a pronounced inverted region so that singlet and triplet metal to ligand electron transfer and thermal ligand to metal back transfer can be investigated. The results will be of interest to chemists in a variety of fields, including spectroscopy, surface catalysis, and chacterization of metalloproteins.
