TY - JOUR
T1 - Switchover of the Mechanism between Electron Transfer and Hydrogen-Atom Transfer for a Protonated Manganese(IV)–Oxo Complex by Changing Only the Reaction Temperature
AU - Jung, Jieun
AU - Kim, Surin
AU - Lee, Yong Min
AU - Nam, Wonwoo
AU - Fukuzumi, Shunichi
N1 - Publisher Copyright:
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2016/6/20
Y1 - 2016/6/20
N2 - Hydroxylation of mesitylene by a nonheme manganese(IV)–oxo complex, [(N4Py)MnIV(O)]2+(1), proceeds via one-step hydrogen-atom transfer (HAT) with a large deuterium kinetic isotope effect (KIE) of 3.2(3) at 293 K. In contrast, the same reaction with a triflic acid-bound manganese(IV)-oxo complex, [(N4Py)MnIV(O)]2+-(HOTf)2(2), proceeds via electron transfer (ET) with no KIE at 293 K. Interestingly, when the reaction temperature is lowered to less than 263 K in the reaction of 2, however, the mechanism changes again from ET to HAT with a large KIE of 2.9(3). Such a switchover of the reaction mechanism from ET to HAT is shown to occur by changing only temperature in the boundary region between ET and HAT pathways when the driving force of ET from toluene derivatives to 2 is around −0.5 eV. The present results provide a valuable and general guide to predict a switchover of the reaction mechanism from ET to the others, including HAT.
AB - Hydroxylation of mesitylene by a nonheme manganese(IV)–oxo complex, [(N4Py)MnIV(O)]2+(1), proceeds via one-step hydrogen-atom transfer (HAT) with a large deuterium kinetic isotope effect (KIE) of 3.2(3) at 293 K. In contrast, the same reaction with a triflic acid-bound manganese(IV)-oxo complex, [(N4Py)MnIV(O)]2+-(HOTf)2(2), proceeds via electron transfer (ET) with no KIE at 293 K. Interestingly, when the reaction temperature is lowered to less than 263 K in the reaction of 2, however, the mechanism changes again from ET to HAT with a large KIE of 2.9(3). Such a switchover of the reaction mechanism from ET to HAT is shown to occur by changing only temperature in the boundary region between ET and HAT pathways when the driving force of ET from toluene derivatives to 2 is around −0.5 eV. The present results provide a valuable and general guide to predict a switchover of the reaction mechanism from ET to the others, including HAT.
KW - bioinorganic chemistry
KW - electron transfer
KW - hydrogen atom transfer
KW - manganese(IV)-oxo complex
KW - mechanism switchover
UR - http://www.scopus.com/inward/record.url?scp=84971238789&partnerID=8YFLogxK
U2 - 10.1002/anie.201602460
DO - 10.1002/anie.201602460
M3 - Article
AN - SCOPUS:84971238789
SN - 1433-7851
VL - 55
SP - 7450
EP - 7454
JO - Angewandte Chemie - International Edition
JF - Angewandte Chemie - International Edition
IS - 26
ER -