Halogenase-mimicking selective chlorination of unactivated C–H bonds by a Fe-complex

In this study, we report a selective aliphatic C-H bond chlorination mediated by Fe-bTAML (bTAML: biuret-modified tetraamido macrocyclic ligand) using sodium hypochlorite as the chlorine source. The reaction predominantly yields chlorinated products over hydroxylated ones across various unactivated C-H bonds in acetonitrile-water medium. The formation of rearranged chlorinated products in norcarane and the absence of stereo-retention in <i>cis</i>-dimethylcyclohexane suggests the involvement of a long-lived, cage-escaped carbon radical intermediate. UV-Vis and EPR spectroscopic analyses confirm the presence of [Fe^V(O)-(NO₂)bTAML]^- (2) as the reactive intermediate. The 3°:2° selectivity in hydrocarbons, kinetic isotope effect (KIE), and detailed kinetic studies indicate hydrogen atom abstraction (HAA) by [Fe^V(O)-(NO₂)bTAML]^- (2) as the rate-determining step.