Electron Spin Resonance (ESR) spectroscopy is a key technique for the study of molecules that contain an unpaired electron. ESR measurements on inorganic, organometallic and organic materials under photochemical, electrochemical and thermal stimulation lead to an understanding of chemical structure that is unattainable by any other technique. The acquisition of ESR instrumentation enhances the ability of chemists to carry out frontier research. The Department of Chemistry of the Massachusetts Institute of Technology and the Francis Bitter National Magnet Laboratory will use this award from the Chemistry Shared Instrumentation Program to aid in the purchase of an ESR spectrometer. Studies in various areas of chemistry will be enhanced and include the following: 1) Polyiron centers in chemistry and biology 2) Cytochrome P450 and nitrogen fixation biochemistry 3) Nickel methanogenisis 4) High oxidation stat molybdenum and tungsten dinitrogen complexes 5) Technetium radiopharmaceuticals and related technetium chemistry 6) ESR studies of organometallic molecules and multicomponent redox reagents 7) Electronics and magnetic properties of iron-sulfur protein site analogues