Nitrene Photochemistry of Manganese N-Haloamides*. Academic Article uri icon

abstract

  • Manganese complexes supported by macrocyclic tetrapyrrole ligands represent an important platform for nitrene transfer catalysis and have been applied to both C-H amination and olefin aziridination catalysis. The reactivity of the transient high-valent Mn nitrenoids that mediate these processes renders characterization of these species challenging. Here we report the synthesis and nitrene transfer photochemistry of a family of MnIII N-haloamide complexes. The S=2 N-haloamide complexes are characterized by 1 HNMR, UV-vis, IR, high-frequency and -field EPR (HFEPR) spectroscopies, and single-crystal X-ray diffraction. Photolysis of these complexes results in the formal transfer of a nitrene equivalent to both C-H bonds, such as the -C-H bonds of tetrahydrofuran, and olefinic substrates, such as styrene, to afford aminated and aziridinated products, respectively. Low-temperature spectroscopy and analysis of kinetic isotope effects for C-H amination indicate halogen-dependent photoreactivity: Photolysis of N-chloroamides proceeds via initial cleavage of the Mn-N bond to generate MnII and amidyl radical intermediates; in contrast, photolysis of N-iodoamides proceeds via N-I cleavage to generate a MnIV nitrenoid (i.e., {MnNR}7 species). These results establish N-haloamide ligands as viable precursors in the photosynthesis of metal nitrenes and highlight the power of ligand design to provide access to reactive intermediates in group-transfer catalysis.

published proceedings

  • Angew Chem Int Ed Engl

altmetric score

  • 17.45

author list (cited authors)

  • Van Trieste, G. P., Reid, K. A., Hicks, M. H., Das, A., Figgins, M. T., Bhuvanesh, N., ... Powers, D. C.

citation count

  • 0

complete list of authors

  • Van Trieste, Gerard P||Reid, Kaleb A||Hicks, Madeline H||Das, Anuvab||Figgins, Matthew T||Bhuvanesh, Nattamai||Ozarowski, Andrew||Telser, Joshua||Powers, David C

publication date

  • January 1, 2021 11:11 AM

publisher