Deciphering the mechanism of O2 reduction with electronically tunable non-heme iron enzyme model complexes

A homologous series of electronically tuned 2,2′,2′′-nitrilotris(N-arylacetamide) pre-ligands (H3LR) were prepared (R = NO2, CN, CF3, F, Cl, Br, Et, Me, H, OMe, NMe2) and some of their corresponding Fe and Zn species synthesized. The iron complexes react rapidly with O2, the final products of which...

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Bibliographic Details
Published in:Chemical science (Cambridge) 2018, Vol.9 (26), p.5773-5780
Main Authors: Surendhran, Roshaan, D'Arpino, Alexander A, Sciscent, Bao Y, Cannella, Anthony F, Friedman, Alan E, MacMillan, Samantha N, Gupta, Rupal, Lacy, David C
Format: Article
Language:English
Subjects:
Chemistry
Construction
Coordination compounds
Crystal structure
Homology
Iron
Nitrogen dioxide
Proteins
Reduction
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Summary:A homologous series of electronically tuned 2,2′,2′′-nitrilotris(N-arylacetamide) pre-ligands (H3LR) were prepared (R = NO2, CN, CF3, F, Cl, Br, Et, Me, H, OMe, NMe2) and some of their corresponding Fe and Zn species synthesized. The iron complexes react rapidly with O2, the final products of which are diferric mu-oxo bridged species. The crystal structure of the oxidized product obtained from DMA solutions contain a structural motif found in some diiron proteins. The mechanism of iron mediated O2 reduction was explored to the extent that allowed us to construct an empirically consistent rate law. A Hammett plot was constructed that enabled insightful information into the rate-determining step and hence allows for a differentiation between two kinetically equivalent O2 reduction mechanisms.
ISSN:2041-6520
2041-6539
DOI:10.1039/c8sc01621f