Intramolecular Redox-Active Ligand-to-Substrate Single-Electron Transfer: Radical Reactivity with a Palladium(II) Complex

Coordination of the redox-active tridentate NNO ligand L-H2 to Pd-II yields the paramagnetic iminobenzosemiquinonato complex 3. Single-electron reduction of 3 yields diamagnetic amidophenolato complex 4, capable of activating aliphatic azide 5. Experimental and computational studies suggest a redox-noninnocent pathway wherein the redox-active ligand facilitates intramolecular ligand-to-substrate single-electron transfer to generate an open-shell singlet nitrene-substrate radical, ligand radical, enabling subsequent radical-type C-H amination reactivity with Pd-II.