Search for: All records

Abstract High‐valent Fe(IV)=O intermediates of metalloenzymes have inspired numerous efforts to generate synthetic analogs to mimic and understand their substrate oxidation reactivities. However, high‐valent M(IV) complexes of late transition metals are rare. We have recently reported a novel Co(IV)−dinitrate complex (1‐NO₃) that activates sp³C−H bonds up to 87 kcal/mol. In this work, we have shown that the nitrate ligands in1‐NO₃can be replaced by azide, a more basic coordinating base, resulting in the formation of a more potent Co(IV)−diazide species (1‐N₃) that reacts with substrates (hydrocarbons and phenols) at faster rate constants and activates stronger C−H bonds than the parent complex1‐NO₃. We have characterized1‐N₃employing a combination of spectroscopic and computational approaches. Our results clearly show that the coordination of azide leads to the modulation of the Co(IV) electronic structure and the Co(IV/III) redox potential. Together with the higher basicity of azide, these thermodynamic parameters contribute to the higher driving forces of1‐N₃than1‐NO₃for C−H bond activation. Our discoveries are thus insightful for designing more reactive bio‐inspired high‐valent late transition metal complexes for activating inert aliphatic hydrocarbons.