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Kojima T. Development of functionality of metal complexes based on proton-coupled electron transfer. Dalton Trans 2020; 49:7284-7293. [DOI: 10.1039/d0dt00898b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Proton-coupled electron transfer (PCET) is ubiquitous and fundamental in many kinds of redox reactions. In this paper, are described PCET reactions in metal complexes to highlight their useful and unique properties and functionalities.
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Affiliation(s)
- Takahiko Kojima
- Department of Chemistry
- Faculty of Pure and Applied Sciences
- University of Tsukuba
- Tsukuba
- Japan
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Ishizuka T, Tobita K, Yano Y, Shiota Y, Yoshizawa K, Fukuzumi S, Kojima T. Proton-Coupled Electron Shuttling in a Covalently Linked Ruthenium–Copper Heterodinuclear Complex. J Am Chem Soc 2011; 133:18570-3. [DOI: 10.1021/ja208141b] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tomoya Ishizuka
- Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
| | - Kengo Tobita
- Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
| | - Yuichi Yano
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, and ALCA, Japan Science and Technology Agency, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Yoshihito Shiota
- Institute for Materials Chemistry and Engineering, Kyushu University, Motooka, Nishi-Ku, Fukuoka 819-0395, Japan
| | - Kazunari Yoshizawa
- Institute for Materials Chemistry and Engineering, Kyushu University, Motooka, Nishi-Ku, Fukuoka 819-0395, Japan
| | - Shunichi Fukuzumi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, and ALCA, Japan Science and Technology Agency, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
- Department of Bioinsipired Science (WCU Project), Ewha Womans University, Seoul 120-750, South Korea
| | - Takahiko Kojima
- Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
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Yano Y, Kojima T, Fukuzumi S. Cooperative catalysis of a trinuclear ruthenium(II) complex in transfer hydrogenation of ketones by formic acid. Inorganica Chim Acta 2011. [DOI: 10.1016/j.ica.2011.01.100] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ishizuka T, Sawaki T, Miyazaki S, Kawano M, Shiota Y, Yoshizawa K, Fukuzumi S, Kojima T. Mechanistic Insights into Photochromic Behavior of a Ruthenium(II)-Pterin Complex. Chemistry 2011; 17:6652-62. [DOI: 10.1002/chem.201003522] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Indexed: 11/06/2022]
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Kojima T, Hirasa N, Noguchi D, Ishizuka T, Miyazaki S, Shiota Y, Yoshizawa K, Fukuzumi S. Synthesis and Characterization of Ruthenium(II)−Pyridylamine Complexes with Catechol Pendants as Metal Binding Sites. Inorg Chem 2010; 49:3737-45. [DOI: 10.1021/ic902070q] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Takahiko Kojima
- Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571
| | - Norihisa Hirasa
- Department of Material and Life Science, Graduate School of Engineering, Osaka University and SORST (JST), 2-1 Yamada-oka, Suita, Osaka 565-0871
| | | | - Tomoya Ishizuka
- Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571
| | - Soushi Miyazaki
- Department of Material and Life Science, Graduate School of Engineering, Osaka University and SORST (JST), 2-1 Yamada-oka, Suita, Osaka 565-0871
| | | | | | - Shunichi Fukuzumi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University and SORST (JST), 2-1 Yamada-oka, Suita, Osaka 565-0871
- Department of Bioinspired Science, Ewha Womans University, Seoul, 120-750, Korea
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Kojima T, Hayashi KI, Iizuka SY, Tani F, Naruta Y, Kawano M, Ohashi Y, Hirai Y, Ohkubo K, Matsuda Y, Fukuzumi S. Synthesis and Characterization of Mononuclear Ruthenium(III) Pyridylamine Complexes and Mechanistic Insights into Their Catalytic Alkane Functionalization withm-Chloroperbenzoic Acid. Chemistry 2007; 13:8212-22. [PMID: 17625799 DOI: 10.1002/chem.200700190] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A series of mononuclear RuIII complexes [RuCl2(L)]+, where L is tris(2-pyridylmethyl)amine (TPA) or one of four TPA derivatives as tetradentate ligand, were prepared and characterized by spectroscopic methods, X-ray crystallography, and electrochemical measurements. The geometry of a RuIII complex having a non-threefold-symmetric TPA ligand bearing one dimethylnicotinamide moiety was determined to show that the nicotine moiety resides trans to a pyridine group, but not to the chlorido ligand. The substituents of the TPA ligands were shown to regulate the redox potential of the ruthenium center, as indicated by a linear Hammett plot in the range of 200 mV for RuIII/RuIV couples with a relatively large rho value (+0.150). These complexes act as effective catalysts for alkane functionalization in acetonitrile with m-chloroperbenzoic acid (mCPBA) as terminal oxidant at room temperature. They exhibited fairly good reactivity for oxidation of cyclohexane (C--H bond energy 94 kcal mol(-1)), and the reactivity can be altered significantly by the electronic effects of substituents on TPA ligands in terms of initial rates and turnover numbers. Catalytic oxygenation of cyclohexane by a RuIII complex with 16O-mCPBA in the presence of H2 18O gave 18O-labeled cyclohexanol with 100% inclusion of the 18O atom from the water molecule. Resonance Raman spectra under catalytic conditions without the substrate indicate formation of a RuIV==O intermediate with lower bonding energy. Kinetic isotope effects (KIEs) in the oxidation of cyclohexane suggest that hydrogen abstraction is the rate-determining step and the KIE values depend on the substituents of the TPA ligands. Thus, the reaction mechanism of catalytic cyclohexane oxygenation depends on the electronic effects of the ligands.
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Affiliation(s)
- Takahiko Kojima
- Department of Chemistry, Faculty of Sciences, Kyushu University, Hakozaki, Higashi-Ku, Fukuoka 812-8581, Japan.
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Kojima T, Miyazaki S, Hayashi KI, Shimazaki Y, Tani F, Naruta Y, Matsuda Y. Intramolecular Rearrangement for Regioselective Complexation by Intramolecular CH/? Interaction in a Hydrophobic Cavity of a Ruthenium Coordination Sphere. Chemistry 2004; 10:6402-10. [PMID: 15532051 DOI: 10.1002/chem.200400496] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A Ru(II) complex with a hydrophobic cavity formed from two 1-naphthoylamide groups was prepared. Its reactions with beta-diketones gave beta-diketonato complexes in which hydrophobic pi-pi or CH/pi interactions were confirmed by NMR spectroscopy and X-ray crystallography. In the case of the asymmetric beta-diketone benzoylacetone, an isomer with a CH/pi interaction was afforded as the sole product owing to thermodynamic control. The reaction was found to involve a novel intramolecular rearrangement from the phenyl-included isomer to the methyl-included one without rupture of Ru-beta-diketonato coordination bonds (activation energy 52 kJ mol(-1)). This indicates that CH/pi interactions can be more favored thermodynamically than pi-pi interactions in a suitable hydrophobic environment.
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Affiliation(s)
- Takahiko Kojima
- Department of Chemistry, Faculty of Sciences, Kyushu University, Hakozaki, Higashi-Ku, Fukuoka 812-8581, Japan
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Akermark B, Bjernemose J, Börje A, Chmielewski PJ, Paulsen H, Simonsen O, Stein PC, Toftlund H, Wolny JA. Strain-induced substitutional lability in a Ru(ii) complex of a hypodentate polypyridine ligand. Dalton Trans 2004:1215-20. [PMID: 15252663 DOI: 10.1039/b316093a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The ruthenium(II) complex of heptadentate N,N,N',N'-tetrakis(2-pyridylmethyl)-2,6-bis(aminomethyl)pyridine (tpap) was isolated as the hexafluorophosphate complex Ru(tpap)(PF6)2. The crystal structure has been determined for the triflate salt Ru(tpap)(CF3SO3)2.2H2O, which crystallizes in the monoclinic space group P2(1)/n. The structure was refined to a final R value of 0.0549 for 5894 observed reflections. The heptadentate ligand coordinates with six nitrogens, i.e. with two tertiary nitrogens and four pyridine nitrogens, one of the pyridines remaining un-coordinated. The resulting structure is significantly distorted from octahedral geometry with an equatorial Nsp3-Ru-Npyridine angle of 120 degrees. The consequence of the above steric strain is a labilization of the system and fluxional behaviour involving exchange between equatorially coordinated and non-coordinated pyridines has been observed by 1H NMR for Ru(tpap)(PF6)2 in d6-acetone solution. The activation parameters of DeltaG(not equal to 298) = 53 kJ mol(-1), DeltaH(not equal) = 56 +/- 1 kJ mol(-1) and DeltaS(not equal) = -10 +/- 3 J mol(-1) K(-1) were determined on the basis of NMR experiments. In addition electronic structure calculations applying density functional theory (DFT) have been performed in order to identify a transition state and to estimate the activation barrier. On the basis of NMR and DFT results the mechanism of isoexchange involving a hepta-coordinated intermediate has been proposed.
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Affiliation(s)
- Björn Akermark
- Stockholms Universitet, Organisk Kemi, Arrheniuslaboratoriet, 106 91 Stockholm, Sweden
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