Formation and Reactivity of a Fleeting Ni ^III Bisphenoxyl Diradical Species

Cytochrome P450s and Galactose Oxidases exploit redox active ligands to form reactive high valent intermediates for oxidation reactions. This strategy works well the late 3d metals where accessing states is rather challenging. Herein, we report of NiII(salen) (salen=N,N′-bis(3,5-di-tert-butyl-salicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with mCPBA (meta-chloroperoxybenzoic acid) a fleeting NiIII bisphenoxyl diradical species, in CH3CN CH2Cl2 at −40 °C. Electrochemical spectroscopic analyses using UV/Vis, EPR, resonance Raman spectroscopies revealed events both on ligand metal centre yield species. DFT calculations found electronic structure d-configuration center be consistent three electron oxidized species can perform hydrogen atom abstraction oxygen transfer