Understanding the Chemistry of Nitrene and Highlighting its Remarkable Catalytic Capabilities as a Non-Heme Iron Enzyme

Nitrogen is a crucial ingredient for biological processes and is necessary for several cellular activities, including metabolic processes, nucleic acid generation, and protein synthesis. Herein we looked at the intricate chemical properties of nitrene, a molecule that contains nitrogen at its core. Nitrene, akin to carbene, exhibits unique reactivity as an electrophile due to its unpaired octet. The electrical arrangement of nitrene, namely in its most basic form as imidogen (HN), is analyzed, with an emphasis on its sp hybridization and spin density characteristics. The formation of nitrene, which is known for its strong reactivity, occurs as an intermediate species through two primary mechanisms: the photolysis or thermolysis of azides, and the decomposition of isocyanates. This study offers a concise elucidation of significant chemical occurrences involving nitrenes, such as the incorporation of C-H bonds, cycloaddition reactions, the observed phenomena of ring contraction and ring expansion in aryl nitrenes and the catalytic reactions through Nitrene radical. The final section of the paper provides a summary focused on a specific study involving the transfer of nitrene, which is assisted by a non-heme iron enzyme. The research examines the catalytic prowess of PsEFE, a non-heme iron enzyme derived from Pseudomonas savastanoi, in nitrene transfer processes.  Through the utilization of directed evolution and the introduction of non-native small-molecule ligands, PsEFE demonstrated an elevated level of aziridination activity. This emphasizes the capability to enhance catalysis by modifying the reliance on ligands. This study advances the understanding of nitrene chemistry and highlights the remarkable catalytic capabilities of a non-heme iron enzyme, opening possibilities for further exploration in the area of biocatalysis with transition metals.