Cytochrome P450s and Galactose Oxidases exploit redox active ligands to form reactive high valent intermediates for oxidation reactions. This strategy works well for the late 3d metals where accessing high valent states is rather challenging. Herein, we report the oxidation of Ni II (salenwith mCPBA (meta-chloroperoxybenzoic acid) to form a fleeting Ni III bisphenoxyl diradical species, in CH 3 CN and CH 2 Cl 2 at À 40 °C. Electrochemical and spectroscopic analyses using UV/Vis, EPR, and resonance Raman spectroscopies revealed oxidation events both on the ligand and the metal centre to yield a Ni III bisphenoxyl diradical species. DFT calculations found the electronic structure of the ligand and the dconfiguration of the metal center to be consistent with a Ni III bisphenoxyl diradical species. This three electron oxidized species can perform hydrogen atom abstraction and oxygen atom transfer reactions.

Haloperoxidase enzymes utilize metal hypohalite species to halogenate aliphatic and aromatic C–H bonds to C–X (X = Cl, Br, I) in nature. In this work, we report the synthesis and...

Cytochrome P450s and Galactose Oxidases exploit redox active ligands to form reactive high valent intermediates for oxidation reactions. This strategy works well for the late 3d metals where accessing high valent states is rather challenging. Herein, we report the oxidation of Ni II (salenwith mCPBA (meta-chloroperoxybenzoic acid) to form a fleeting Ni III bisphenoxyl diradical species, in CH 3 CN and CH 2 Cl 2 at À 40 °C. Electrochemical and spectroscopic analyses using UV/Vis, EPR, and resonance Raman spectroscopies revealed oxidation events both on the ligand and the metal centre to yield a Ni III bisphenoxyl diradical species. DFT calculations found the electronic structure of the ligand and the dconfiguration of the metal center to be consistent with a Ni III bisphenoxyl diradical species. This three electron oxidized species can perform hydrogen atom abstraction and oxygen atom transfer reactions.

Inspired by copper-based metalloenzymes, we aim to incorporate amino acids into our ligands to facilitate active copper intermediates that serve as functional and structural models for these enzymes. Herein, we...

The reaction of [(L)MnII]2+ (L = neutral polypyridine ligand framework) in the presence of mCPBA (m‐chloroperoxybenzoic acid) generates a putative Mn(V)=O species at RT. The proposed Mn(V)=O species is capable of performing the aromatic hydroxylation of Cl‐benzoic acid derived from mCPBA to give [(L)MnIII(m‐Cl‐salicylate)]+, which in the presence of excess mCPBA generates a metastable [(L)MnV(O)(m‐Cl‐salicylate)]+, characterized by UV/Vis absorption, EPR, resonance Raman spectroscopy, and ESI‐MS studies. The current study highlights the fact that [(L)MnIII(m‐Cl‐salicylate)]+ formation may not be a dead end for catalysis. Further, a plausible mechanism has been proposed for the formation of [(L)MnV(O)‐m‐Cl‐salicylate)]+ from [(L)MnIII(m‐Clsalicylate)]+. The characterized transient [(L)MnV(O)‐m‐Cl‐salicylate)]+ reported in the current work exhibits high reactivity for oxygen atom transfer reactions, supported by the electrophilic character depicted from Hammett studies using a series of para‐substituted thioanisoles. The unprecedented study starting from a non‐heme neutral polypyridine ligand framework paves a path for mimicking the natural active site of photosystem II under ambient conditions. Finally, evaluating the intracellular effect of Mn(II) complexes revealed an enhanced intracellular ROS and mitochondrial dysfunction to prevent the proliferation of hepatocellular carcinoma and breast cancer cells.