This project in the Inorganic, Bioinorganic and Organometallic Chemistry Program is in the area of transition metal chemistry. The goal of the project is the synthesis of iron compounds which bind and carry atmospheric oxygen without being destroyed by reaction with the oxygen. Such compounds are important as models of the proteins which transport oxygen, such as hemoglobin and myoglobin, and also for possible practical use in the separation and storage of oxygen. Totally synthetic substances will be designed which reproduce the functions of heme proteins. Emphasis will be on modeling those heme proteins which form iron-dioxygen adducts as they function. Ongoing studies have yielded rare examples of iron-based dioxygen carriers that do not utilize the porphyrin ligand, and structural refinements have yielded examples that are fully functional under ambient conditions. Further studies are expected to generalize the structural principles that have evolved and lead to predictive control over oxygen affinities. Kinetic and mechanistic studies will provide insight into the fundamental processes of binding and dissociation of oxygen and the autoxidation of iron oxygen carriers.