Redox Reactivity of a Mononuclear Manganese-Oxo Complex Binding Calcium Ion and Other Redox-Inactive Metal Ions

Muniyandi Sankaralingam, Yong Min Lee, Yuliana Pineda-Galvan, Deepika G. Karmalkar, Mi Sook Seo, So Hyun Jeon, Yulia Pushkar, Shunichi Fukuzumi, Wonwoo Nam

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Abstract

Mononuclear nonheme manganese(IV)-oxo complexes binding calcium ion and other redox-inactive metal ions, [(dpaq)Mn IV (O)] + -M n+ (1-M n+ , M n+ = Ca 2+ , Mg 2+ , Zn 2+ , Lu 3+ , Y 3+ , Al 3+ , and Sc 3+ ) (dpaq = 2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-yl-acetamidate), were synthesized by reacting a hydroxomanganese(III) complex, [(dpaq)Mn III (OH)] + , with iodosylbenzene (PhIO) in the presence of redox-inactive metal ions (M n+ ). The Mn(IV)-oxo complexes were characterized using various spectroscopic techniques. In reactivity studies, we observed contrasting effects of M n+ on the reactivity of 1-M n+ in redox reactions such as electron-transfer (ET), oxygen atom transfer (OAT), and hydrogen atom transfer (HAT) reactions. In the OAT and ET reactions, the reactivity order of 1-M n+ , such as 1-Sc 3+ ≈ 1-Al 3+ > 1-Y 3+ > 1-Lu 3+ > 1-Zn 2+ > 1-Mg 2+ > 1-Ca 2+ , follows the Lewis acidity of M n+ bound to the Mn-O moiety; that is, the stronger the Lewis acidity of M n+ , the higher the reactivity of 1-M n+ becomes. In sharp contrast, the reactivity of 1-M n+ in the HAT reaction was reversed, giving the reactivity order 1-Ca 2+ > 1-Mg 2+ > 1-Zn 2+ > 1-Lu 3+ > 1-Y 3+ > 1-Al 3+ ≈ 1-Sc 3+ that is, the higher is Lewis acidity of M n+ , the lower the reactivity of 1-M n+ in the HAT reaction. The latter result implies that the Lewis acidity of M n+ bound to the Mn-O moiety can modulate the basicity of the metal-oxo moiety, thus influencing the HAT reactivity of 1-M n+ cytochrome P450 utilizes the axial thiolate ligand to increase the basicity of the iron-oxo moiety, which enhances the reactivity of compound I in C-H bond activation reactions.

Original languageEnglish
Pages (from-to)1324-1336
Number of pages13
JournalJournal of the American Chemical Society
Volume141
Issue number3
DOIs
StatePublished - 23 Jan 2019

Bibliographical note

Funding Information:
This work was supported by the NRF of Korea through CRI (NRF-2012R1A3A2048842 to W.N.), GRL (NRF-2010-00353 to W.N.) and Basic Science Research Program (2017R1D1A1B03029982 to Y.-M.L. and 2017R1D1A1B03032615 to S.F.) and a Grant-in-Aid (no. 16H02268 to S.F.) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), a SENTAN project from Japan Science and Technology (JST) to S.F, and also by the National Science Foundation, Division of Chemistry CHE-1350909 (Y.P.). The use of the Advanced Photon Source an Office of Science User Facility operated by the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory was supportedbythe U.S. DOE under Contract DE-AC02-06CH11357.

Funding Information:
This work was supported by the NRF of Korea through CRI (NRF-2012R1A3A2048842 to W.N.), GRL (NRF-2010-00353 to W.N.), and Basic Science Research Program (2017R1D1A1B03029982 to Y.-M.L. and 2017R1D1A1B03032615 to S.F.) and a Grant-in-Aid (no. 16H02268 to S.F.) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), a SENTAN project from Japan Science and Technology (JST) to S.F, and also by the National Science Foundation, Division of Chemistry CHE-1350909 (Y.P.). The use of the Advanced Photon Source, an Office of Science User Facility operated by the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supportedbythe U.S. DOE under Contract DE-AC02-06CH11357. The PNC/XSD (Sector 20) facilities at the Advanced Photon Source and research at these facilities were supported by the U.S. Department of Energy, Basic Energy Science and the Canadian Light Source.

Publisher Copyright:
© 2018 American Chemical Society.

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