TY - JOUR
T1 - DFT Study on Fe(IV)-Peroxo Formation and H Atom Transfer Triggered O2 Activation by NiFe Complex
AU - Isegawa, Miho
AU - Sharma, Akhilesh K.
AU - Ogo, Seiji
AU - Morokuma, Keiji
N1 - Funding Information:
This paper is dedicated to the memory of Prof. Keiji Morokuma. We thank W. M. C. Sameera and Takahiro Matsumoto for their insightful comments and suggestions. M.I. acknowledges the Fukui Fellowship, Kyoto University. This work was in part supported by Grants-in-Aid for Scientific Research (KAKENHI 15H00938 and 15H02158) to to K.M. and S.O. acknowledges partial support by Grants-in-Aid for Specially Promoted Research (26000008) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT). Computer resources at the Academic Center for Computing and Media Studies at Kyoto University, Research Center of Computer Science at the Institute for Molecular Science are also acknowledged.
Publisher Copyright:
Copyright © 2018 American Chemical Society.
PY - 2018/5/29
Y1 - 2018/5/29
N2 - The mechanism for dioxygen activation using the biomimetic model complex of [NiFe]-hydrogenase, [NiLFe(η5-C5Me5)]+ [L = N,N′-diethyl-3,7-diazanonane-1,9-dithiolato] was established using density functional theory (DFT) and artificial force-induced reaction (AFIR) methods. Our computational results suggest that O2 binds to the FeII center in an end-on fashion and forms a high-valent iron complex, NiFe-peroxo (NiIIFeIV(η2-O2)), which has been experimentally observed. The O-O bond cleavage occurs in the presence of borohydride (BH4-) through hydrogen atom transfer (HAT). Once the HAT occurs, the generated BH3 radical anion (BH3•-) binds to the terminal oxygen of NiFe-OOH, giving rise to BH3OH- and NiIIFeIV O. The second HAT from BH4- to the oxygen of NiIIFeIV O leads to BH3OH- and Fe-reduced NiIIFeII complex. Importantly, the dioxygen activation is triggered by HAT, not by proton transfer or hydride transfer. The O2 is activated by the Fe center, and the oxidation state of Fe varies during the process, while the oxidation state of Ni is conserved. These mechanistic insights into O2 activation are essential in understanding the formation of the inactive state and reactivation process in hydrogenase.
AB - The mechanism for dioxygen activation using the biomimetic model complex of [NiFe]-hydrogenase, [NiLFe(η5-C5Me5)]+ [L = N,N′-diethyl-3,7-diazanonane-1,9-dithiolato] was established using density functional theory (DFT) and artificial force-induced reaction (AFIR) methods. Our computational results suggest that O2 binds to the FeII center in an end-on fashion and forms a high-valent iron complex, NiFe-peroxo (NiIIFeIV(η2-O2)), which has been experimentally observed. The O-O bond cleavage occurs in the presence of borohydride (BH4-) through hydrogen atom transfer (HAT). Once the HAT occurs, the generated BH3 radical anion (BH3•-) binds to the terminal oxygen of NiFe-OOH, giving rise to BH3OH- and NiIIFeIV O. The second HAT from BH4- to the oxygen of NiIIFeIV O leads to BH3OH- and Fe-reduced NiIIFeII complex. Importantly, the dioxygen activation is triggered by HAT, not by proton transfer or hydride transfer. The O2 is activated by the Fe center, and the oxidation state of Fe varies during the process, while the oxidation state of Ni is conserved. These mechanistic insights into O2 activation are essential in understanding the formation of the inactive state and reactivation process in hydrogenase.
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U2 - 10.1021/acs.organomet.8b00098
DO - 10.1021/acs.organomet.8b00098
M3 - Article
AN - SCOPUS:85047774270
SN - 0276-7333
VL - 37
SP - 1534
EP - 1545
JO - Organometallics
JF - Organometallics
IS - 10
ER -