Spectroscopic and quantum chemical characterization of the electronic structure and bonding in a non-heme FeIV[double bond]O complex.

High valent FeIV=O species are key intermediates in the catalytic cycles of many mononuclear non-heme iron enzymes involving the binding and activation of dioxygen. Using variable temperature magnetic circular dichroism (VT MCD) spectroscopy and experimentally calibrated density functional calculations, we are able to present the first detailed description of the electronic structure of a non-heme FeIV=O S = 1 complex. These studies define the nature of the FeIV=O bond and present the basis for understanding high-valent oxygen intermediates in non-heme iron enzymes.