DFT mechanistic study of biomimetic diiron complex catalyzed dehydrogenation: Unexpected Fe(III)Fe(III)-1,1-μ-hydroperoxy active species for hydride abstraction.

The diiron active site is pivotal in catalyzing transformations in both biological and chemical systems. Recently, a range of biomimetic diiron catalysts have been synthesized, drawing inspiration from the active architecture of soluble methane monooxygenase (sMMO). These catalysts have been successfully deployed for the dehydrogenation of indolines, marking a significant advancement in the field. Using density functional theory (DFT) calculations, we have identified a novel mechanistic pathway that governs the dehydrogenation of indolines catalyzed by a biomimetic diiron complex. Specifically, this reaction is facilitated by the transfer of a hybrid atom from the C 1 position of the substrate to the distal oxygen atom of the Fe(III)Fe(III)-1,1-μ-hydroperoxy active species. This transfer serves as the rate-limiting step for the heterolytic cleavage of the O O bond, ultimately generating the substrate cation. The mechanism we propose aligns well with mechanistic investigations incorporating both kinetic isotope effect (KIE) measurements and evaluations of stereochemical selectivity. This research contributes to the broader scientific understanding of catalysis involving biomimetic diiron complexes and offers valuable insights into the catalytic behaviors of non-heme diiron metalloenzymes. In this study, DFT calculations were performed to identify a novel mechanistic pathway that governs the dehydrogenation of indolines catalyzed by a biomimetic diiron complex. Specifically, this reaction is facilitated by the transfer of a hybrid atom from the C 1 position of the substrate to the distal oxygen atom of the Fe(III)Fe(III)-1,1-μ-hydroperoxy active species. [Display omitted] • The biomimetic diiron complex catalyzes the dehydrogenation of indolines via a novel mechanistic pathway. • The reaction proceeds by hybrid transfer from substrate to the Fe(III)Fe(III)-1,1-μ-hydroperoxy active species. • This research expands our understanding on the catalysis of biomimetic diiron complexes and non-heme diiron metalloenzymes. [ABSTRACT FROM AUTHOR]