Volume 234, 2022

Intermediate-spin iron(iv)-oxido species with record reactivity

Abstract

The nonheme iron(IV)-oxido complex trans-N3-[(L1)FeIV[double bond, length as m-dash]O(Cl)]+, where L1 is a derivative of the tetradentate bispidine 2,4-di(pyridine-2-yl)-3,7-diazabicyclo[3.3.1]nonane-1-one, has an S = 1 electronic ground state and is the most reactive nonheme iron model system known so far, of a similar order of reactivity as nonheme iron enzymes (C–H abstraction of cyclohexane, −90 °C (propionitrile), t1/2 = 3.5 s). The reaction with cyclohexane selectively leads to chlorocyclohexane, but “cage escape” at the [(L1)FeIII(OH)(Cl)]+/cyclohexyl radical intermediate lowers the productivity. Ligand field theory is used herein to analyze the d–d transitions of [(L1)FeIV[double bond, length as m-dash]O(X)]n+ (X = Cl, Br, MeCN) in comparison with the thoroughly characterized ferryl complex of tetramethylcyclam (TMC = L2; [(L2)FeIV[double bond, length as m-dash]O(MeCN)]2+). The ligand field parameters and d–d transition energies are shown to provide important information on the triplet–quintet gap and its correlation with oxidation reactivity.

Graphical abstract: Intermediate-spin iron(iv)-oxido species with record reactivity

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
18 अक्तूबर 2021
Accepted
08 नवम्बर 2021
First published
08 नवम्बर 2021

Faraday Discuss., 2022,234, 232-244

Intermediate-spin iron(IV)-oxido species with record reactivity

P. Comba, G. Nunn, F. Scherz and P. H. Walton, Faraday Discuss., 2022, 234, 232 DOI: 10.1039/D1FD00073J

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