151
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Janardanan D, Wang Y, Schyman P, Que L, Shaik S. The fundamental role of exchange-enhanced reactivity in C-H activation by S=2 oxo iron(IV) complexes. Angew Chem Int Ed Engl 2010; 49:3342-5. [PMID: 20358569 PMCID: PMC2882195 DOI: 10.1002/anie.201000004] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
It is shown that H-abstraction reactivity by oxoiron(IV) complexes with a quintet ground state is highly enhanced due to exchange-stabilization endowed by the increased number of the exchange d-d interactions near the transition state . It is postulated that nonheme enzymes evolved to make use of this fundamental mechanism in activation of strong C-H bonds.
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Affiliation(s)
- Deepa Janardanan
- Department of Organic Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University, Jerusalem, 91904, Israel, Fax: (+972) 2-6584680
| | - Yong Wang
- Department of Organic Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University, Jerusalem, 91904, Israel, Fax: (+972) 2-6584680
| | - Patric Schyman
- Department of Organic Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University, Jerusalem, 91904, Israel, Fax: (+972) 2-6584680
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, Fax: (+1) 612-624-7029
| | - Sason Shaik
- Department of Organic Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University, Jerusalem, 91904, Israel, Fax: (+972) 2-6584680
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152
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Janardanan D, Wang Y, Schyman P, Que L, Shaik S. The Fundamental Role of Exchange-Enhanced Reactivity in CH Activation by S=2 Oxo Iron(IV) Complexes. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201000004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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153
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Balcells D, Clot E, Eisenstein O. C—H Bond Activation in Transition Metal Species from a Computational Perspective. Chem Rev 2010; 110:749-823. [PMID: 20067255 DOI: 10.1021/cr900315k] [Citation(s) in RCA: 843] [Impact Index Per Article: 60.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- David Balcells
- Institut Charles Gerhardt, Université Montpellier 2, CNRS 5253, cc 1501, Place Eugène Bataillon, 34000 Montpellier, France
| | - Eric Clot
- Institut Charles Gerhardt, Université Montpellier 2, CNRS 5253, cc 1501, Place Eugène Bataillon, 34000 Montpellier, France
| | - Odile Eisenstein
- Institut Charles Gerhardt, Université Montpellier 2, CNRS 5253, cc 1501, Place Eugène Bataillon, 34000 Montpellier, France
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154
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Afagh N, Yudin A. Chemoselectivity and the Curious Reactivity Preferences of Functional Groups. Angew Chem Int Ed Engl 2010; 49:262-310. [DOI: 10.1002/anie.200901317] [Citation(s) in RCA: 226] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Nicholas A. Afagh
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6 (Canada)
| | - Andrei K. Yudin
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6 (Canada)
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155
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Fukuzumi S, Kotani H, Suenobu T, Hong S, Lee YM, Nam W. Contrasting Effects of Axial Ligands on Electron-Transfer Versus Proton-Coupled Electron-Transfer Reactions of Nonheme Oxoiron(IV) Complexes. Chemistry 2010; 16:354-61. [DOI: 10.1002/chem.200901163] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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156
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Coates CM, Nelson AGD, Goldsmith CR. Assessing the impact of inductive electronic effects on the metrical parameters and reactivity of a series of ferrous complexes. Inorganica Chim Acta 2010. [DOI: 10.1016/j.ica.2009.08.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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157
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Nebe T, Beitat A, Würtele C, Dücker-Benfer C, van Eldik R, McKenzie CJ, Schindler S. Reinvestigation of the formation of a mononuclear Fe(iii) hydroperoxido complex using high pressure kinetics. Dalton Trans 2010; 39:7768-73. [DOI: 10.1039/c0dt00247j] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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158
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Cheng L, Wang J, Wang M, Wu Z. Theoretical studies on the reaction mechanism of alcohol oxidation by high-valent iron-oxo complex of non-heme ligand. Phys Chem Chem Phys 2010; 12:4092-103. [DOI: 10.1039/b917906b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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159
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Zhang H, Chen D, Zhang Y, Zhang G, Liu J. On the mechanism of carbonyl hydrogenation catalyzed by iron catalyst. Dalton Trans 2010; 39:1972-8. [DOI: 10.1039/b919779f] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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160
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Cho KB, Shaik S, Nam W. Theoretical predictions of a highly reactive non-heme Fe(iv)O complex with a high-spin ground state. Chem Commun (Camb) 2010; 46:4511-3. [DOI: 10.1039/c0cc00292e] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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161
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Afagh N, Yudin A. Chemoselektivität und die eigentümlichen Reaktivitäten funktioneller Gruppen. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200901317] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Nicholas A. Afagh
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6 (Kanada)
| | - Andrei K. Yudin
- Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6 (Kanada)
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162
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Cramer CJ, Truhlar DG. Density functional theory for transition metals and transition metal chemistry. Phys Chem Chem Phys 2009; 11:10757-816. [PMID: 19924312 DOI: 10.1039/b907148b] [Citation(s) in RCA: 1079] [Impact Index Per Article: 71.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We introduce density functional theory and review recent progress in its application to transition metal chemistry. Topics covered include local, meta, hybrid, hybrid meta, and range-separated functionals, band theory, software, validation tests, and applications to spin states, magnetic exchange coupling, spectra, structure, reactivity, and catalysis, including molecules, clusters, nanoparticles, surfaces, and solids.
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Affiliation(s)
- Christopher J Cramer
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455-0431, USA.
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163
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Kang Y, Chen H, Jeong YJ, Lai W, Bae EH, Shaik S, Nam W. Enhanced Reactivities of Iron(IV)-Oxo Porphyrin π-Cation Radicals in Oxygenation Reactions by Electron-Donating Axial Ligands. Chemistry 2009; 15:10039-46. [DOI: 10.1002/chem.200901238] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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164
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Hessenauer-Ilicheva N, Franke A, Wolak M, Higuchi T, van Eldik R. Spectroscopic and Mechanistic Studies on Oxidation Reactions Catalyzed by the Functional Model SR Complex for Cytochrome P450: Influence of Oxidant, Substrate, and Solvent. Chemistry 2009; 15:12447-59. [DOI: 10.1002/chem.200901712] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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165
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de Visser SP, Nam W. The effect and influence of cis-ligands on the electronic and oxidizing properties of nonheme oxoiron biomimetics. A density functional study. J Phys Chem A 2009; 112:12887-95. [PMID: 18616332 DOI: 10.1021/jp8018556] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Density functional theory studies on the nature of the cis effect and cis influence of ligands on oxoiron nonheme complexes have been performed. A detailed analysis of the electronic and oxidizing properties of [Fe(IV)O(TPA)L](+) with L = F(-), Cl(-), and Br(-) and TPA = tris-(2-pyridylmethyl)amine are presented and compared with [Fe(IV)O(TPA)NCCH(3)](2+). The calculations show that the electronic cis effect is determined by favorable orbital overlap between first-row elements with the metal, which are missing between the metal and second- and third-row elements. As a consequence, the metal 3d block is split into a one-below-two set of orbitals with L = Cl(-) and Br(-), and the HOMO/LUMO energy gap is widened with respect to the system with L = F(-). However, this larger HOMO/LUMO gap does not lead to large differences in electron affinities of the complexes. Moreover, a quantum mechanical analysis of the binding of the ligand shows that it is built up from a large electric field effect of the ligand on the oxoiron species and a much smaller quantum mechanical effect due to orbital overlap. These contributions are of similar strength for the three tested halogen cis ligands and result in similar reactivity patterns with substrates. The calculations show that [Fe(IV)O(TPA)L](+) with L = F(-), Cl(-), and Br(-) have closely lying triplet and quintet spin states, but only the quintet spin state is reactive with substrates. Therefore, the efficiency of the oxidant will be determined by the triplet-quintet spin state crossing of the reaction. The reaction of styrene with a doubly charged reactant, that is, [Fe(V)O(TPA)L](2+) with L = F(-), Cl(-), and Br(-) or [Fe(V)O(TPA)NCCH(3)](3+), leads to an initial electron transfer from the substrate to the metal followed by a highly exothermic epoxidation mechanism. These reactivity differences are mainly determined by the overall charge of the system rather than the nature of the cis ligand.
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Affiliation(s)
- Sam P de Visser
- The Manchester Interdisciplinary Biocenter and the School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK.
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166
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Latifi R, Bagherzadeh M, de Visser SP. Origin of the correlation of the rate constant of substrate hydroxylation by nonheme iron(IV)-oxo complexes with the bond-dissociation energy of the C-H bond of the substrate. Chemistry 2009; 15:6651-62. [PMID: 19472231 DOI: 10.1002/chem.200900211] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Mononuclear nonheme iron containing systems are versatile and vital oxidants of substrate hydroxylation reactions in many biosystems, whereby the rate constant of hydroxylation correlates with the strength of the C-H bond that is broken in the process. The thermodynamic reason behind these correlations, however, has never been established. In this work results of a series of density functional theory calculations of substrate hydroxylation by a mononuclear nonheme iron(IV)-oxo oxidant with a 2 His/1 Asp structural motif analogous to alpha-ketoglutarate dependent dioxygenases are presented. The calculations show that these oxidants are very efficient and able to hydroxylate strong C-H bonds, whereby the hydrogen abstraction barriers correlate linearly with the strength of the C-H bond of the substrate that is broken. These trends have been rationalized using a valence bond (VB) curve-crossing diagram, which explains the correlation using electron transfer mechanisms in the hydrogen abstraction processes. We also rationalized the subsequent reaction step for radical rebound and show that the barrier is proportional to the electron affinity of the iron(III)-hydroxo intermediate complex. It is shown that nonheme iron(IV)-hydroxo complexes have a larger electron affinity than heme iron(IV)-hydroxo complexes and therefore also experience larger radical rebound barriers, which may have implications for product distributions and rearrangement reactions. Thus, detailed comparisons between heme and nonheme iron(IV)-oxo oxidants reveal the fundamental differences in monoxygenation capabilities of these important classes of oxidants in biosystems and synthetic analogues for the first time and enable us to make predictions of experimental processes.
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Affiliation(s)
- Reza Latifi
- The Manchester Interdisciplinary Biocentre and the School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, UK
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167
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de Visser S, Tahsini L, Nam W. How Does the Axial Ligand of Cytochrome P450 Biomimetics Influence the Regioselectivity of Aliphatic versus Aromatic Hydroxylation? Chemistry 2009; 15:5577-87. [DOI: 10.1002/chem.200802234] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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168
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Annaraj J, Cho J, Lee YM, Kim S, Latifi R, de Visser S, Nam W. Structural Characterization and Remarkable Axial Ligand Effect on the Nucleophilic Reactivity of a Nonheme Manganese(III)-Peroxo Complex. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200900118] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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169
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Annaraj J, Cho J, Lee YM, Kim S, Latifi R, de Visser S, Nam W. Structural Characterization and Remarkable Axial Ligand Effect on the Nucleophilic Reactivity of a Nonheme Manganese(III)-Peroxo Complex. Angew Chem Int Ed Engl 2009; 48:4150-3. [DOI: 10.1002/anie.200900118] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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170
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Klinker EJ, Shaik S, Hirao H, Que L. A two-state reactivity model explains unusual kinetic isotope effect patterns in C-H bond cleavage by nonheme oxoiron(IV) complexes. Angew Chem Int Ed Engl 2009; 48:1291-5. [PMID: 19130517 DOI: 10.1002/anie.200804029] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
It's in the bond: The cleavage of C-H bonds by two related oxoiron(IV) complexes shows a range of kinetic isotope effect (KIE) values that exhibit an unusual dependence on the C-H bond strength. Large nonclassical KIEs are observed for bond strengths below 93 kcal mol(-1), while semiclassical values are found above this value (see graph, DHA = 9,10-dihydroanthracene). This nonintuitive behavior can be rationalized by invoking a two-state reactivity model.
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Affiliation(s)
- Eric J Klinker
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN 55455, USA
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171
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Solomon EI, Wong SD, Liu LV, Decker A, Chow MS. Peroxo and oxo intermediates in mononuclear nonheme iron enzymes and related active sites. Curr Opin Chem Biol 2009; 13:99-113. [PMID: 19278895 DOI: 10.1016/j.cbpa.2009.02.011] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 01/25/2009] [Accepted: 02/02/2009] [Indexed: 10/21/2022]
Abstract
Fe(III)OOH and Fe(IV)O intermediates have now been documented in a number of nonheme iron active sites. In this Current Opinion we use spectroscopy combined with electronic structure calculations to define the frontier molecular orbitals (FMOs) of these species and their contributions to reactivity. For the low-spin Fe(III)OOH species in activated bleomycin we show that the reactivity of this nonheme iron intermediate is very different from that of the analogous Compound 0 of cytochrome P450. For Fe(IV)O S=1 model species we experimentally define the electronic structure and its contribution to reactivity, and computationally evaluate how this would change for the Fe(IV)O S=2 intermediates found in nonheme iron enzymes.
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Affiliation(s)
- Edward I Solomon
- Department of Chemistry, Stanford University, CA 94305, United States.
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172
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de Visser SP, Straganz GD. Why Do Cysteine Dioxygenase Enzymes Contain a 3-His Ligand Motif Rather than a 2His/1Asp Motif Like Most Nonheme Dioxygenases? J Phys Chem A 2009; 113:1835-46. [DOI: 10.1021/jp809700f] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sam P. de Visser
- The Manchester Interdisciplinary Biocenter and the School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom, and Graz University of Technology, Institute of Biotechnology and Biochemical Engineering, Petersgasse 12, A-8010 Graz, Austria
| | - Grit D. Straganz
- The Manchester Interdisciplinary Biocenter and the School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom, and Graz University of Technology, Institute of Biotechnology and Biochemical Engineering, Petersgasse 12, A-8010 Graz, Austria
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173
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Ye S, Neese F. Quantum chemical studies of C–H activation reactions by high-valent nonheme iron centers. Curr Opin Chem Biol 2009; 13:89-98. [DOI: 10.1016/j.cbpa.2009.02.007] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 02/04/2009] [Accepted: 02/04/2009] [Indexed: 11/16/2022]
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174
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Wang Y, Wang Y, Han K. Theoretical study of cyclohexane hydroxylation by three possible isomers of [FeIV(O)(R-TPEN)] 2+: does the pentadentate ligand wrapping around the metal center differently lead to the different stability and reactivity? J Biol Inorg Chem 2009; 14:533-45. [PMID: 19172312 DOI: 10.1007/s00775-009-0468-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Accepted: 12/31/2008] [Indexed: 11/26/2022]
Abstract
Density functional theory calculations have been carried out to elucidate the mechanism of cyclohexane hydroxylation by three possible isomers of [Fe(IV)(O)(N-R-N,N',N'-tris(2-pyridylmethyl)ethane-1,2-diamine)](2+) (R is methyl or benzyl) (Klinker et al. in Angew Chem Int Ed 44:3690-3694, 2005). The calculations offer a mechanistic view and reveal the following features: (a) all the three isomers possess triplet ground states and low-lying quintet excited states, (b) the relative stability follows the order isomer A > isomer B > isomer C, in agreement with the conclusions of Klinker et al., (c) the theoretical investigations provide a rationale to explain the interconversion of the three isomers, (d) the reaction pathways of the C-H hydroxylation are initiated by a hydrogen-abstraction step, and (e) the three isomers react with cyclohexane via two-state-reactivity patterns on competing triplet and quintet spin-state surfaces. As such, in the gas phase, the relative reactivity exhibits the trend isomer B > isomer A, while at the highest level, B2//B1 with zero point energy and solvation corrections, the relative reactivity follows the order isomer B > isomer A > isomer C. Thus, the calculated reaction pathway shows that pyridine rings perpendicular to the Fe-O axis result in more reactive species, and a pyridine ring coordinated trans to the oxygen atom leads to the least reactive isomer.
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Affiliation(s)
- Yi Wang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, People's Republic of China
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175
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Klinker E, Shaik S, Hirao H, Que L. A Two-State Reactivity Model Explains Unusual Kinetic Isotope Effect Patterns in CH Bond Cleavage by Nonheme Oxoiron(IV) Complexes. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200804029] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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176
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Cheng L, Wang J, Wang M, Wu Z. Theoretical studies on the reaction mechanism of oxidation of primary alcohols by Zn/Cu(ii)-phenoxyl radical catalyst. Dalton Trans 2009:3286-97. [DOI: 10.1039/b817985a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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177
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Balcells D, Raynaud C, Crabtree RH, Eisenstein O. A rational basis for the axial ligand effect in C-H oxidation by [MnO(porphyrin)(X)]+ (X = H2O, OH-, O2-) from a DFT study. Inorg Chem 2008; 47:10090-9. [PMID: 18788735 DOI: 10.1021/ic8013706] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Oxyl radical character in the MnO group of the title system is shown from a density functional theory study to be essential for efficient C-H cleavage, which is a key step in C-H oxidation. Since oxyl species have elongated Mn-O bonds relative to the more usual oxo species of type MnO, the normal expectation would be that high trans-influence ligands X should facilitate oxyl character by elongating the Mn-O bond and thus enhance both oxyl character and reactivity. Contrary to this expectation, but in line with the experimental data (Jin, N.; Ibrahim, M.; Spiro, T. G.; Groves, J. T. J. Am. Chem. Soc. 2007, 129, 12416), we find that reactivity increases along the series X = O(2-) < OH(-) < H2O for the following reasons. The ground-state singlet (S) is unreactive for all X, and only the higher-energy triplet (T) and quintet (Q) states have the oxyl character needed for reactivity, but the higher trans-influence X ligands are also shown to increase the S/T and S/Q gaps, thus making attainment of the needed T and Q states harder. The latter effect is dominant, and high trans-influence X ligands thus disfavor reaction. The higher reactivity in the presence of acid noted by Groves and co-workers is thus rationalized by the preference for having X = H2O over OH(-) or O(2-).
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Affiliation(s)
- David Balcells
- Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-UM2-ENSCM-UM1, Universite Montpellier 2, cc-1501 Place Eugene Bataillon, 34095, Montpellier, France
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178
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Nonheme “FeIV
O” Models: Ab Initio Analysis of the Low-Energy Spin State Electronic Structures. Eur J Inorg Chem 2008. [DOI: 10.1002/ejic.200800724] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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179
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Jackson TA, Rohde JU, Seo MS, Sastri CV, DeHont R, Stubna A, Ohta T, Kitagawa T, Münck E, Nam W, Que L. Axial ligand effects on the geometric and electronic structures of nonheme oxoiron(IV) complexes. J Am Chem Soc 2008; 130:12394-407. [PMID: 18712873 DOI: 10.1021/ja8022576] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of complexes [Fe(IV)(O)(TMC)(X)](+) (where X = OH(-), CF3CO2(-), N3(-), NCS(-), NCO(-), and CN(-)) were obtained by treatment of the well-characterized nonheme oxoiron(IV) complex [Fe(IV)(O)(TMC)(NCMe)](2+) (TMC = tetramethylcyclam) with the appropriate NR4X salts. Because of the topology of the TMC macrocycle, the [Fe(IV)(O)(TMC)(X)](+) series represents an extensive collection of S = 1 oxoiron(IV) complexes that only differ with respect to the ligand trans to the oxo unit. Electronic absorption, Fe K-edge X-ray absorption, resonance Raman, and Mossbauer data collected for these complexes conclusively demonstrate that the characteristic spectroscopic features of the S = 1 Fe(IV)=O unit, namely, (i) the near-IR absorption properties, (ii) X-ray absorption pre-edge intensities, and (iii) quadrupole splitting parameters, are strongly dependent on the identity of the trans ligand. However, on the basis of extended X-ray absorption fine structure data, most [Fe(IV)(O)(TMC)(X)](+) species have Fe=O bond lengths similar to that of [Fe(IV)(O)(TMC)(NCMe)](2+) (1.66 +/- 0.02 A). The mechanisms by which the trans ligands perturb the Fe(IV)=O unit were probed using density functional theory (DFT) computations, yielding geometric and electronic structures in good agreement with our experimental data. These calculations revealed that the trans ligands modulate the energies of the Fe=O sigma- and pi-antibonding molecular orbitals, causing the observed spectroscopic changes. Time-dependent DFT methods were used to aid in the assignment of the intense near-UV absorption bands found for the oxoiron(IV) complexes with trans N3(-), NCS(-), and NCO(-) ligands as X(-)-to-Fe(IV)=O charge-transfer transitions, thereby rationalizing the resonance enhancement of the nu(Fe=O) mode upon excitation of these chromophores.
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Affiliation(s)
- Timothy A Jackson
- Department of Chemistry and Center for Metals in Biocatalysis, 207 Pleasant Street S.E., University of Minnesota, Minneapolis, Minnesota 55455, USA
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180
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Lakmini H, Ciofini I, Jutand A, Amatore C, Adamo C. Pd-Catalyzed Homocoupling Reaction of Arylboronic Acid: Insights from Density Functional Theory. J Phys Chem A 2008; 112:12896-903. [DOI: 10.1021/jp801948u] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- H. Lakmini
- Laboratoire d’Electrochimie et Chimie Analytique, Ecole Nationale Supérieure de Chimie, UMR CNRS 7575, 11 Rue Pierre et Marie Curie, F-75231 Paris Cedex 5, France, and Département de Chimie, Ecole Normale Supérieure, UMR CNRS-ENS-UPMC 8640, 24 Rue Lhomond, F-75231 Paris Cedex 5, France
| | - I. Ciofini
- Laboratoire d’Electrochimie et Chimie Analytique, Ecole Nationale Supérieure de Chimie, UMR CNRS 7575, 11 Rue Pierre et Marie Curie, F-75231 Paris Cedex 5, France, and Département de Chimie, Ecole Normale Supérieure, UMR CNRS-ENS-UPMC 8640, 24 Rue Lhomond, F-75231 Paris Cedex 5, France
| | - A. Jutand
- Laboratoire d’Electrochimie et Chimie Analytique, Ecole Nationale Supérieure de Chimie, UMR CNRS 7575, 11 Rue Pierre et Marie Curie, F-75231 Paris Cedex 5, France, and Département de Chimie, Ecole Normale Supérieure, UMR CNRS-ENS-UPMC 8640, 24 Rue Lhomond, F-75231 Paris Cedex 5, France
| | - C. Amatore
- Laboratoire d’Electrochimie et Chimie Analytique, Ecole Nationale Supérieure de Chimie, UMR CNRS 7575, 11 Rue Pierre et Marie Curie, F-75231 Paris Cedex 5, France, and Département de Chimie, Ecole Normale Supérieure, UMR CNRS-ENS-UPMC 8640, 24 Rue Lhomond, F-75231 Paris Cedex 5, France
| | - C. Adamo
- Laboratoire d’Electrochimie et Chimie Analytique, Ecole Nationale Supérieure de Chimie, UMR CNRS 7575, 11 Rue Pierre et Marie Curie, F-75231 Paris Cedex 5, France, and Département de Chimie, Ecole Normale Supérieure, UMR CNRS-ENS-UPMC 8640, 24 Rue Lhomond, F-75231 Paris Cedex 5, France
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Dhuri S, Seo M, Lee YM, Hirao H, Wang Y, Nam W, Shaik S. Experiment and Theory Reveal the Fundamental Difference between Two-State and Single-State Reactivity Patterns in Nonheme FeIVO versus RuIVO Oxidants. Angew Chem Int Ed Engl 2008; 47:3356-9. [DOI: 10.1002/anie.200705880] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Dhuri S, Seo M, Lee YM, Hirao H, Wang Y, Nam W, Shaik S. Experiment and Theory Reveal the Fundamental Difference between Two-State and Single-State Reactivity Patterns in Nonheme FeIVO versus RuIVO Oxidants. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200705880] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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