Trapping an Elusive Fe(IV)-Superoxo Intermediate Inside a Self-Assembled Nanocage at Room Temperature

Natural metalloenzymes stabilize reactive intermediates through specific metal-substrate interactions in protein confinement. Using the structural blueprint of enzyme pockets it is possible to trap elusive intermediates inside molecular cavities. Here we demonstrate room temperature trapping of a rare yet stable Fe(IV)-superoxo [FeIV(O2)-bTAML] intermediate subsequent to dioxygen binding at the Fe(III) site of a (Et4N)2[FeIII(Cl)(bTAML)] catalyst confined inside the hydrophobic interior of a water-soluble Pd6L412+ nanocage.