Abstract: 

Although the activation of inert C–H bonds by metal-oxo complexes has been widely studied, important questions remain, particularly regarding the roles of oxygen spin population (i.e., unpaired electrons on the oxo ligand), the antiferromagnetic coupling and low lying excited states in facilitating C–H bond cleavage. In order to investigate these factors, we have utilized experimental and computational methods. Pulse EPR experiments were performed on isotopically labelled heme enzyme compound I intermediates to measure spin populations and semiempirical modeling was utilized to relate spectroscopically obtained parameters to information about the excited states.