Nuclear Resonance Vibrational Spectroscopy on the FeIVO S=2 Non‐Heme Site in TMG3tren: Experimentally Calibrated Insights into Reactivity

Dissecting the barrier: The nuclear resonance vibrational spectrum of the S=2 [(TMG3tren)FeIVO] complex revealed features indicative of an axial “steric wall” that contributes to the overall reaction barrier. DFT calculations show that both S=2 (axial attack) and S=1 (equatorial attack) surfaces possess steric contributions to their barriers, and estimates of these steric effects result in comparable intrinsic barriers for both spin surfaces (see picture).