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Title (Primary) Outer-sphere electron transfer does not underpin B12-dependent olefinic reductive dehalogenation in anaerobes
Author Zhang, S.; Adrian, L.; Schüürmann, G.
Journal Physical Chemistry Chemical Physics
Year 2021
Department OEC; UBT
Volume 23
Issue 48
Page From 27520
Page To 27524
Language englisch
Topic T9 Healthy Planet
T7 Bioeconomy
Supplements https://www.rsc.org/suppdata/d1/cp/d1cp04632b/d1cp04632b1.pdf?_ga=2.71380565.776078540.1639749217-195691874.1639749217
Abstract Anaerobic microbial B12-dependent reductive dehalogenation may pave a way to remediate soil, sediment, and underground water contaminated with halogenated olefins. The chemical reaction is initiated by electron transfer (ET) from supernucleophilic cob(I)alamin (B12s). However, the inherent mechanism as outer-sphere or inner-sphere route is still under debate. To clarify the possibility of an outer-sphere pathway, we calculated free energy barriers of the initial steps of all outer-sphere ET routes by Marcus theory employing density functional theory (DFT). For 18 fluorinated, chlorinated, and brominated ethenes as representative olefins, 164 of 165 reactions with free energy barriers larger than 20 kcal mol−1 are not feasible under physiological dehalogenase conditions. Moreover, electronic structure analysis of perbromoethene with an outer-sphere free energy barrier of 18.2 kcal mol−1 reveals no ET initiation down to CoBr and CoC distances of 3.15 Å. The results demonstrate that the B12-catalyzed reductive dechlorination of olefins in microbes should proceed through an inner-sphere ET pathway.
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=25481
Zhang, S., Adrian, L., Schüürmann, G. (2021):
Outer-sphere electron transfer does not underpin B12-dependent olefinic reductive dehalogenation in anaerobes
Phys. Chem. Chem. Phys. 23 (48), 27520 - 27524