51
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McDonald AR, Que L. High-valent nonheme iron-oxo complexes: Synthesis, structure, and spectroscopy. Coord Chem Rev 2013. [DOI: 10.1016/j.ccr.2012.08.002] [Citation(s) in RCA: 397] [Impact Index Per Article: 36.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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52
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Wilson SA, Chen J, Hong S, Lee YM, Clémancey M, Garcia-Serres R, Nomura T, Ogura T, Latour JM, Hedman B, Hodgson KO, Nam W, Solomon EI. [Fe(IV)═O(TBC)(CH3CN)]2+: comparative reactivity of iron(IV)-oxo species with constrained equatorial cyclam ligation. J Am Chem Soc 2012; 134:11791-806. [PMID: 22708532 DOI: 10.1021/ja3046298] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[Fe(IV)═O(TBC)(CH(3)CN)](2+) (TBC = 1,4,8,11-tetrabenzyl-1,4,8,11-tetraazacyclotetradecane) is characterized, and its reactivity differences relative to [Fe(IV)═O(TMC)(CH(3)CN)](2+) (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) are evaluated in hydrogen atom (H-atom) abstraction and oxo-transfer reactions. Structural differences are defined using X-ray absorption spectroscopy and correlated to reactivities using density functional theory. The S = 1 ground states are highly similar and result in large activation barriers (~25 kcal/mol) due to steric interactions between the cyclam chelate and the substrate (e.g., ethylbenzene) associated with the equatorial π-attack required by this spin state. Conversely, H-atom abstraction reactivity on an S = 2 surface allows for a σ-attack with an axial substrate approach. This results in decreased steric interactions with the cyclam and a lower barrier (~9 kcal/mol). For [Fe(IV)═O(TBC)(CH(3)CN)](2+), the S = 2 excited state in the reactant is lower in energy and therefore more accessible at the transition state due to a weaker ligand field associated with the steric interactions of the benzyl substituents with the trans-axial ligand. This study is further extended to the oxo-transfer reaction, which is a two-electron process requiring both σ- and π-electron transfer and thus a nonlinear transition state. In oxo-transfer, the S = 2 has a lower barrier due to sequential vs concerted (S = 1) two electron transfer which gives a high-spin ferric intermediate at the transition state. The [Fe(IV)═O(TBC)(CH(3)CN)](2+) complex is more distorted at the transition state, with the iron farther out of the equatorial plane due to the steric interaction of the benzyl groups with the trans-axial ligand. This allows for better orbital overlap with the substrate, a lower barrier, and an increased rate of oxo-transfer.
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Affiliation(s)
- Samuel A Wilson
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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53
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Talsi EP, Bryliakov KP. Chemo- and stereoselective CH oxidations and epoxidations/cis-dihydroxylations with H2O2, catalyzed by non-heme iron and manganese complexes. Coord Chem Rev 2012. [DOI: 10.1016/j.ccr.2012.04.005] [Citation(s) in RCA: 314] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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54
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Ye W, Staples RJ, Rybak-Akimova EV. Oxygen atom transfer mediated by an iron(IV)/iron(II) macrocyclic complex containing pyridine and tertiary amine donors. J Inorg Biochem 2012; 115:1-12. [PMID: 22922287 DOI: 10.1016/j.jinorgbio.2012.05.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Revised: 05/08/2012] [Accepted: 05/10/2012] [Indexed: 11/19/2022]
Abstract
A new non-heme iron model complex containing a high-spin iron(II) complexed with N-methylated pyridine-containing macrocycle was synthesized and crystallographically characterized. The complex generates peroxo- and high-valent iron-oxo intermediates in reactions with tert-butylhydroperoxide and isopropyl 2-iodoxybenzoate, respectively, allowing to gain insight into the formation and reactivity of enzyme-like intermediates related to biological oxygen activation. The formation and reactivity of these intermediate species were investigated by the stopped-flow methodology. The mechanism of oxygen transfer to organic substrates involving reaction of oxoiron(IV) intermediate was elucidated on the basis of spectroscopic and kinetic data. Incorporation of a pyridine ring into the macrocycle increased the reactivity of the Fe(IV)=O intermediates in comparison with polyamine tetraaza macrocyclic complexes: ferryl (Fe(IV)=O) species derived from 3 demonstrated electrophilic reactivity in transferring an oxygen atom to substituted triarylphosphines and to olefins (such as cyclooctene). However, iron(III) alkylperoxo intermediate was unreactive with cyclooctene.
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Affiliation(s)
- Wanhua Ye
- Department of Chemistry, Tufts University, Medford, MA 02155, USA
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55
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Ye W, Ho DM, Friedle S, Palluccio TD, Rybak-Akimova EV. Role of Fe(IV)-oxo intermediates in stoichiometric and catalytic oxidations mediated by iron pyridine-azamacrocycles. Inorg Chem 2012; 51:5006-21. [PMID: 22534174 DOI: 10.1021/ic202435r] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An iron(II) complex with a pyridine-containing 14-membered macrocyclic (PyMAC) ligand L1 (L1 = 2,7,12-trimethyl-3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1(17),13,15-triene), 1, was prepared and characterized. Complex 1 contains low-spin iron(II) in a pseudo-octahedral geometry as determined by X-ray crystallography. Magnetic susceptibility measurements (298 K, Evans method) and Mössbauer spectroscopy (90 K, δ = 0.50(2) mm/s, ΔE(Q) = 0.78(2) mm/s) confirmed that the low-spin configuration of Fe(II) is retained in liquid and frozen acetonitrile solutions. Cyclic voltammetry revealed a reversible one-electron oxidation/reduction of the iron center in 1, with E(1/2)(Fe(III)/Fe(II)) = 0.49 V vs Fc(+)/Fc, a value very similar to the half-wave potentials of related macrocyclic complexes. Complex 1 catalyzed the epoxidation of cyclooctene and other olefins with H(2)O(2). Low-temperature stopped-flow kinetic studies demonstrated the formation of an iron(IV)-oxo intermediate in the reaction of 1 with H(2)O(2) and concomitant partial ligand oxidation. A soluble iodine(V) oxidant, isopropyl 2-iodoxybenzoate, was found to be an excellent oxygen atom donor for generating Fe(IV)-oxo intermediates for additional spectroscopic (UV-vis in CH(3)CN: λ(max) = 705 nm, ε ≈ 240 M(-1) cm(-1); Mössbauer: δ = 0.03(2) mm/s, ΔE(Q) = 2.00(2) mm/s) and kinetic studies. The electrophilic character of the (L1)Fe(IV)═O intermediate was established in rapid (k(2) = 26.5 M(-1) s(-1) for oxidation of PPh(3) at 0 °C), associative (ΔH(‡) = 53 kJ/mol, ΔS(‡) = -25 J/K mol) oxidation of substituted triarylphosphines (electron-donating substituents increased the reaction rate, with a negative value of Hammet's parameter ρ = -1.05). Similar double-mixing kinetic experiments demonstrated somewhat slower (k(2) = 0.17 M(-1) s(-1) at 0 °C), clean, second-order oxidation of cyclooctene into epoxide with preformed (L1)Fe(IV)═O that could be generated from (L1)Fe(II) and H(2)O(2) or isopropyl 2-iodoxybenzoate. Independently determined rates of ferryl(IV) formation and its subsequent reaction with cyclooctene confirmed that the Fe(IV)-oxo species, (L1)Fe(IV)═O, is a kinetically competent intermediate for cyclooctene epoxidation with H(2)O(2) at room temperature. Partial ligand oxidation of (L1)Fe(IV)═O occurs over time in oxidative media, reducing the oxidizing ability of the ferryl species; the macrocyclic nature of the ligand is retained, resulting in ferryl(IV) complexes with Schiff base PyMACs. NH-groups of the PyMAC ligand assist the oxygen atom transfer from ferryl(IV) intermediates to olefin substrates.
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Affiliation(s)
- Wanhua Ye
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, USA
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56
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Thibon A, Jollet V, Ribal C, Sénéchal-David K, Billon L, Sorokin AB, Banse F. Hydroxylation of Aromatics with the Help of a Non-Haem FeOOH: A Mechanistic Study under Single-Turnover and Catalytic Conditions. Chemistry 2012; 18:2715-24. [DOI: 10.1002/chem.201102252] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Indexed: 11/12/2022]
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57
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Bigi JP, Harman WH, Lassalle-Kaiser B, Robles DM, Stich TA, Yano J, Britt RD, Chang CJ. A high-spin iron(IV)-oxo complex supported by a trigonal nonheme pyrrolide platform. J Am Chem Soc 2012; 134:1536-42. [PMID: 22214221 DOI: 10.1021/ja207048h] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the generation and characterization of a new high-spin iron(IV)-oxo complex supported by a trigonal nonheme pyrrolide platform. Oxygen-atom transfer to [(tpa(Mes))Fe(II)](-) (tpa(Ar) = tris(5-arylpyrrol-2-ylmethyl)amine) in acetonitrile solution affords the Fe(III)-alkoxide product [(tpa(Mes2MesO))Fe(III)](-) resulting from intramolecular C-H oxidation with no observable ferryl intermediates. In contrast, treatment of the phenyl derivative [(tpa(Ph))Fe(II)](-) with trimethylamine N-oxide in acetonitrile solution produces the iron(IV)-oxo complex [(tpa(Ph))Fe(IV)(O)](-) that has been characterized by a suite of techniques, including mass spectrometry as well as UV-vis, FTIR, Mössbauer, XAS, and parallel-mode EPR spectroscopies. Mass spectral, FTIR, and optical absorption studies provide signatures for the iron-oxo chromophore, and Mössbauer and XAS measurements establish the presence of an Fe(IV) center. Moreover, the Fe(IV)-oxo species gives parallel-mode EPR features indicative of a high-spin, S = 2 system. Preliminary reactivity studies show that the high-spin ferryl tpa(Ph) complex is capable of mediating intermolecular C-H oxidation as well as oxygen-atom transfer chemistry.
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Affiliation(s)
- Julian P Bigi
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, USA
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58
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Cappillino PJ, McNally JS, Wang F, Caradonna JP. The effect of varying carboxylate ligation on the electronic environment of N2Ox(x = 1–3) nonheme iron: A DFT analysis. Dalton Trans 2012; 41:474-83. [DOI: 10.1039/c1dt11199j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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59
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Cappillino PJ, Miecznikowski JR, Tyler LA, Tarves PC, McNally JS, Lo W, Kasibhatla BST, Krzyaniak MD, McCracken J, Wang F, Armstrong WH, Caradonna JP. Studies of iron(ii) and iron(iii) complexes with fac-N2O, cis-N2O2 and N2O3 donor ligands: models for the 2-His 1-carboxylate motif of non-heme iron monooxygenases. Dalton Trans 2012; 41:5662-77. [DOI: 10.1039/c2dt11096b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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60
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Kumar D, Sastry GN, Goldberg DP, de Visser SP. Mechanism of S-oxygenation by a cysteine dioxygenase model complex. J Phys Chem A 2011; 116:582-91. [PMID: 22091701 DOI: 10.1021/jp208230g] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In this work, we present the first computational study on a biomimetic cysteine dioxygenase model complex, [Fe(II)(LN(3)S)](+), in which LN(3)S is a tetradentate ligand with a bis(imino)pyridyl scaffold and a pendant arylthiolate group. The reaction mechanism of sulfur dioxygenation with O(2) was examined by density functional theory (DFT) methods and compared with results obtained for cysteine dioxygenase. The reaction proceeds via multistate reactivity patterns on competing singlet, triplet, and quintet spin state surfaces. The reaction mechanism is analogous to that found for cysteine dioxygenase enzymes (Kumar, D.; Thiel, W.; de Visser, S. P. J. Am. Chem. Soc. 2011, 133, 3869-3882); hence, the computations indicate that this complex can closely mimic the enzymatic process. The catalytic mechanism starts from an iron(III)-superoxo complex and the attack of the terminal oxygen atom of the superoxo group on the sulfur atom of the ligand. Subsequently, the dioxygen bond breaks to form an iron(IV)-oxo complex with a bound sulfenato group. After reorganization, the second oxygen atom is transferred to the substrate to give a sulfinic acid product. An alternative mechanism involving the direct attack of dioxygen on the sulfur, without involving any iron-oxygen intermediates, was also examined. Importantly, a significant energetic preference for dioxygen coordinating to the iron center prior to attack at sulfur was discovered and serves to elucidate the function of the metal ion in the reaction process. The computational results are in good agreement with experimental observations, and the differences and similarities of the biomimetic complex and the enzymatic cysteine dioxygenase center are highlighted.
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Affiliation(s)
- Devesh Kumar
- Molecular Modelling Group, Indian Institute of Chemical Technology, Hyderabad 500-607, India.
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61
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Hong S, Lee YM, Cho KB, Sundaravel K, Cho J, Kim MJ, Shin W, Nam W. Ligand Topology Effect on the Reactivity of a Mononuclear Nonheme Iron(IV)-Oxo Complex in Oxygenation Reactions. J Am Chem Soc 2011; 133:11876-9. [DOI: 10.1021/ja204008u] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Seungwoo Hong
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
- Department of Chemistry and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Seoul 121-742, Korea
| | - Yong-Min Lee
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
| | - Kyung-Bin Cho
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
| | | | - Jaeheung Cho
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
| | - Myoung Jin Kim
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
| | - Woonsup Shin
- Department of Chemistry and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Seoul 121-742, Korea
| | - Wonwoo Nam
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
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62
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Soo HS, Sougrati MT, Grandjean F, Long GJ, Chang CJ. A seven-coordinate iron platform and its oxo and nitrene reactivity. Inorganica Chim Acta 2011. [DOI: 10.1016/j.ica.2010.12.040] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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63
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Kumar D, Thiel W, de Visser SP. Theoretical Study on the Mechanism of the Oxygen Activation Process in Cysteine Dioxygenase Enzymes. J Am Chem Soc 2011; 133:3869-82. [DOI: 10.1021/ja107514f] [Citation(s) in RCA: 169] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Devesh Kumar
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1,
D-45470 Mülheim an der Ruhr, Germany
- Molecular Modelling Group, Indian Institute of Chemical Technology, Hyderabad
500 607, India
| | - Walter Thiel
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1,
D-45470 Mülheim an der Ruhr, Germany
| | - Sam P. de Visser
- The Manchester Interdisciplinary
Biocenter and School of Chemical Engineering and Analytical Science, University of Manchester, 131 Princess Street, Manchester
M1 7DN, United Kingdom
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64
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Makhlynets OV, Rybak-Akimova EV. Aromatic hydroxylation at a non-heme iron center: observed intermediates and insights into the nature of the active species. Chemistry 2011; 16:13995-4006. [PMID: 21117047 DOI: 10.1002/chem.201002577] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mechanism of substrate oxidations with hydrogen peroxide in the presence of a highly reactive, biomimetic, iron aminopyridine complex, [Fe(II)(bpmen)(CH(3)CN)(2)][ClO(4)](2) (1; bpmen=N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)ethane-1,2-diamine), is elucidated. Complex 1 has been shown to be an excellent catalyst for epoxidation and functional-group-directed aromatic hydroxylation using H(2)O(2), although its mechanism of action remains largely unknown. Efficient intermolecular hydroxylation of unfunctionalized benzene and substituted benzenes with H(2)O(2) in the presence of 1 is found in the present work. Detailed mechanistic studies of the formation of iron(III)-phenolate products are reported. We have identified, generated in high yield, and experimentally characterized the key Fe(III)(OOH) intermediate (λ(max)=560 nm, rhombic EPR signal with g=2.21, 2.14, 1.96) formed by 1 and H(2)O(2). Stopped-flow kinetic studies showed that Fe(III)(OOH) does not directly hydroxylate the aromatic rings, but undergoes rate-limiting self-decomposition producing transient reactive oxidant. The formation of the reactive species is facilitated by acid-assisted cleavage of the O-O bond in the iron-hydroperoxide intermediate. Acid-assisted benzene hydroxylation with 1 and a mechanistic probe, 2-Methyl-1-phenyl-2-propyl hydroperoxide (MPPH), correlates with O-O bond heterolysis. Independently generated Fe(IV)=O species, which may originate from O-O bond homolysis in Fe(III)(OOH), proved to be inactive toward aromatic substrates. The reactive oxidant derived from 1 exchanges its oxygen atom with water and electrophilically attacks the aromatic ring (giving rise to an inverse H/D kinetic isotope effect of 0.8). These results have revealed a detailed experimental mechanistic picture of the oxidation reactions catalyzed by 1, based on direct characterization of the intermediates and products, and kinetic analysis of the individual reaction steps. Our detailed understanding of the mechanism of this reaction revealed both similarities and differences between synthetic and enzymatic aromatic hydroxylation reactions.
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Affiliation(s)
- Olga V Makhlynets
- Department of Chemistry, Tufts University, 62 Talbot Ave., Medford, MA 02155, USA
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65
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Company A, Prat I, Frisch JR, Ballesté RM, Güell M, Juhász G, Ribas X, Münck E, Luis JM, Que L, Costas M. Modeling the cis-oxo-labile binding site motif of non-heme iron oxygenases: water exchange and oxidation reactivity of a non-heme iron(IV)-oxo compound bearing a tripodal tetradentate ligand. Chemistry 2011; 17:1622-34. [PMID: 21268165 PMCID: PMC3097279 DOI: 10.1002/chem.201002297] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Indexed: 11/11/2022]
Abstract
The spectroscopic and chemical characterization of a new synthetic non-heme iron(IV)-oxo species [Fe(IV)(O)((Me,H) Pytacn)(S)](2+) (2, (Me,H)Pytacn=1-(2'-pyridylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane, S=CH(3)CN or H(2)O) is described. Complex 2 was prepared by reaction of [Fe(II)(CF(3)SO(3))(2)((Me,H) Pytacn)] (1) with peracetic acid. Complex 2 bears a tetradentate N(4) ligand that leaves two cis sites available for binding an oxo group and a second external ligand but, unlike the related iron(IV)-oxo species with tetradentate ligands, it is remarkably stable at room temperature (t(1/2)>2 h at 288 K). Its ability to exchange the oxygen atom of the oxo ligand with water has been analyzed in detail by means of kinetic studies, and a mechanism is proposed on the basis of DFT calculations. Hydrogen-atom abstraction from C-H bonds and oxygen-atom transfer to sulfides by 2 have also been studied. Despite its thermal stability, 2 proves to be a very powerful oxidant that is capable of breaking the strong C-H bond of cyclohexane (bond dissociation energy=99.3 kcal mol(-1)).
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Affiliation(s)
- Anna Company
- Departament de Química, Universitat de Girona, Campus Montilivi, E17071 Girona, Catalonia (Spain), Fax: +34 972 41 81 50
| | - Irene Prat
- Departament de Química, Universitat de Girona, Campus Montilivi, E17071 Girona, Catalonia (Spain), Fax: +34 972 41 81 50
| | - Jonathan R. Frisch
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455 (USA)
| | - Ruben Mas Ballesté
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455 (USA)
| | - Mireia Güell
- Institut de Química Computacional, Universitat de Girona, Campus Montilivi, E17071 Girona, Catalonia (Spain)
| | - Gergely Juhász
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213
| | - Xavi Ribas
- Departament de Química, Universitat de Girona, Campus Montilivi, E17071 Girona, Catalonia (Spain), Fax: +34 972 41 81 50
| | - Eckard Münck
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213
| | - Josep M. Luis
- Institut de Química Computacional, Universitat de Girona, Campus Montilivi, E17071 Girona, Catalonia (Spain)
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455 (USA)
| | - Miquel Costas
- Departament de Química, Universitat de Girona, Campus Montilivi, E17071 Girona, Catalonia (Spain), Fax: +34 972 41 81 50
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66
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Seo MS, Kim NH, Cho KB, So JE, Park SK, Clémancey M, Garcia-Serres R, Latour JM, Shaik S, Nam W. A mononuclear nonheme iron(iv)-oxo complex which is more reactive than cytochrome P450 model compound I. Chem Sci 2011. [DOI: 10.1039/c1sc00062d] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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67
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Karamzadeh B, Kumar D, Sastry GN, de Visser SP. Steric Factors Override Thermodynamic Driving Force in Regioselectivity of Proline Hydroxylation by Prolyl-4-hydroxylase Enzymes. J Phys Chem A 2010; 114:13234-43. [DOI: 10.1021/jp1089855] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Baharan Karamzadeh
- 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 Molecular Modelling Group, Indian Institute of Chemical Technology, Hyderabad 500-607, India
| | - Devesh Kumar
- 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 Molecular Modelling Group, Indian Institute of Chemical Technology, Hyderabad 500-607, India
| | - G. Narahari Sastry
- 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 Molecular Modelling Group, Indian Institute of Chemical Technology, Hyderabad 500-607, India
| | - 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 Molecular Modelling Group, Indian Institute of Chemical Technology, Hyderabad 500-607, India
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68
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Oldenburg PD, Feng Y, Pryjomska-Ray I, Ness D, Que L. Olefin Cis-Dihydroxylation with Bio-Inspired Iron Catalysts. Evidence for an FeII/FeIV Catalytic Cycle. J Am Chem Soc 2010; 132:17713-23. [DOI: 10.1021/ja1021014] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Paul D. Oldenburg
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Yan Feng
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Iweta Pryjomska-Ray
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Daniel Ness
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
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69
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Wang Y, Han K. Steric hindrance effect of the equatorial ligand on Fe(IV)O and Ru(IV)O complexes: a density functional study. J Biol Inorg Chem 2010; 15:351-9. [PMID: 19916032 DOI: 10.1007/s00775-009-0607-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Accepted: 11/04/2009] [Indexed: 10/20/2022]
Abstract
The geometric structures and mechanisms for hydrogen abstraction from cyclohexane for four high-valent complexes, [Fe IV(O)(TMC)(NCMe)]2+ (where TMC is 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane; 1-NCMe), the inverted isomer [Fe IV(NCMe)(TMC)(O)]2+ (2-NCMe), [Ru IV(O)(TMC)(NCMe)]2+ (the ruthenium analogue of 1-NCMe; 3-NCMe), and the inverted isomer [Ru IV(NCMe)(TMC)(O)]2+ (4-NCMe), were investigated using density functional theory. The axial NCMe ligand was found to be sterically more hindered in 2-NCMe than in 1-NCMe, which is in accord with the calculated results that the Fe-L axial distance is longer in the former. Both 1-NCMe and 2-NCMe are capable of hydrogen abstraction from cyclohexane via two-state reactivity patterns. In contrast, 3-NCMe and 4-NCMe react with cyclohexane by a single-state mechanism. The reaction pathways computed reveal that 2-NCMe is more reactive than 1-NCMe, in agreement with experimental results, whereas the reactivity of 3-NCMe and 4-NCMe shows little dependence on whether the oxo unit is syn or anti to the four N-methyl groups. Our analysis shows that along the reaction pathway for 2-NCMe in the triplet spin state, the NCMe ligand moves away from the iron center, and therefore the energy of the sigma *2 z (alpha-spin) orbital decreases and an electron is transferred to this orbital. Finally, we calculated the kinetic isotope effect and investigated the relationship between this effect and reaction barriers.
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Affiliation(s)
- Yi Wang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023 Dalian, People's Republic of China
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70
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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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71
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Pijper D, Saisaha P, de Boer JW, Hoen R, Smit C, Meetsma A, Hage R, van Summeren RP, Alsters PL, Feringa BL, Browne WR. The unexpected role of pyridine-2-carboxylic acid in manganese based oxidation catalysis with pyridin-2-yl based ligands. Dalton Trans 2010; 39:10375-81. [DOI: 10.1039/c0dt00452a] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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72
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Soo HS, Komor AC, Iavarone AT, Chang CJ. A Hydrogen-Bond Facilitated Cycle for Oxygen Reduction by an Acid- and Base-Compatible Iron Platform. Inorg Chem 2009; 48:10024-35. [DOI: 10.1021/ic9006668] [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)
- Han Sen Soo
- Department of Chemistry
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | | | | | - Christopher J. Chang
- Department of Chemistry
- Howard Hughes Medical Institute, University of California, Berkeley, California 94720
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
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73
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Company A, Feng Y, Güell M, Ribas X, Luis J, Que L, Costas M. Olefin-Dependent Discrimination between Two Nonheme HOFeVO Tautomeric Species in Catalytic H2O2Epoxidations. Chemistry 2009; 15:3359-62. [DOI: 10.1002/chem.200802597] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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74
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Annaraj J, Kim S, Seo MS, Lee YM, Kim Y, Kim SJ, Choi YS, Jang HG, Nam W. An iron(II) complex with a N3S2 thioether ligand in the generation of an iron(IV)-oxo complex and its reactivity in olefin epoxidation. Inorganica Chim Acta 2009. [DOI: 10.1016/j.ica.2008.04.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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75
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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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76
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Thibon A, Bartoli JF, Bourcier S, Banse F. Mononuclear iron complexes relevant to nonheme iron oxygenases. Synthesis, characterizations and reactivity of Fe-Oxo and Fe-Peroxo intermediates. Dalton Trans 2009:9587-94. [DOI: 10.1039/b913470k] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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77
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Fukuzumi S, Kotani H, Lee YM, Nam W. Sequential electron-transfer and proton-transfer pathways in hydride-transfer reactions from dihydronicotinamide adenine dinucleotide analogues to non-heme oxoiron(IV) complexes and p-chloranil. Detection of radical cations of NADH analogues in acid-promoted hydride-transfer reactions. J Am Chem Soc 2008; 130:15134-42. [PMID: 18937476 DOI: 10.1021/ja804969k] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hydride transfer from dihydronicotinamide adenine dinucleotide (NADH) analogues, such as 10-methyl-9,10-dihydroacridine (AcrH 2) and its derivatives, 1-benzyl-1,4-dihydronicotinamide (BNAH), and their deuterated compounds, to non-heme oxoiron(IV) complexes such as [(L)Fe (IV)(O)] (2+) (L = N4Py, Bn-TPEN, and TMC) occurs to yield the corresponding NAD (+) analogues and non-heme iron(II) complexes in acetonitrile. Hydride transfer from the NADH analogues to p-chloranil (Cl 4Q) also occurs to produce the corresponding NAD (+) analogues and the hydroquinone anion (Cl 4QH (-)). The logarithms of the observed second-order rate constants (log k H) of hydride transfer from NADH analogues to non-heme oxoiron(IV) complexes are linearly correlated with those of hydride transfer from the same series of NADH analogues to Cl 4Q, including similar kinetic deuterium isotope effects. The log k H values of hydride transfer from NADH analogues to non-heme oxoiron(IV) complexes are also linearly correlated with those of deprotonation of the radical cations of NADH analogues. Such linear correlations indicate that overall hydride-transfer reactions of NADH analogues to both non-heme oxoiron(IV) complexes and Cl 4Q occur via electron transfer from NADH analogues to the oxoiron(IV) complexes, followed by rate-limiting deprotonation from the radical cations of NADH analogues and subsequent rapid electron transfer from the deprotonated radicals to the Fe(III) complexes to yield the corresponding NAD (+) analogues and the Fe(II) complexes. The electron-transfer pathway was accelerated by the presence of perchloric acid, and the resulting radical cations of NADH analogues were detected by electron spin resonance spectroscopy and UV-vis spectrophotometry in the acid-promoted hydride-transfer reactions from NADH analogues to non-heme oxoiron(IV) complexes. This result provides the first direct evidence that a hydride transfer from NADH analogues to non-heme oxoiron(IV) complexes proceeds via an electron-transfer pathway.
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Affiliation(s)
- Shunichi Fukuzumi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, SORST, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan.
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78
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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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79
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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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80
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Strautmann JBH, George SD, Bothe E, Bill E, Weyhermüller T, Stammler A, Bögge H, Glaser T. Molecular and Electronic Structures of Mononuclear Iron Complexes Using Strongly Electron-Donating Ligands and their Oxidized Forms. Inorg Chem 2008; 47:6804-24. [DOI: 10.1021/ic800335t] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Julia B. H. Strautmann
- Fakultät für Chemie, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany, Stanford Synchrotron Radiation Laboratory, SLAC, Stanford University, Stanford, California 94309, and Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim, Germany
| | - Serena DeBeer George
- Fakultät für Chemie, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany, Stanford Synchrotron Radiation Laboratory, SLAC, Stanford University, Stanford, California 94309, and Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim, Germany
| | - Eberhard Bothe
- Fakultät für Chemie, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany, Stanford Synchrotron Radiation Laboratory, SLAC, Stanford University, Stanford, California 94309, and Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim, Germany
| | - Eckhard Bill
- Fakultät für Chemie, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany, Stanford Synchrotron Radiation Laboratory, SLAC, Stanford University, Stanford, California 94309, and Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim, Germany
| | - Thomas Weyhermüller
- Fakultät für Chemie, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany, Stanford Synchrotron Radiation Laboratory, SLAC, Stanford University, Stanford, California 94309, and Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim, Germany
| | - Anja Stammler
- Fakultät für Chemie, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany, Stanford Synchrotron Radiation Laboratory, SLAC, Stanford University, Stanford, California 94309, and Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim, Germany
| | - Hartmut Bögge
- Fakultät für Chemie, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany, Stanford Synchrotron Radiation Laboratory, SLAC, Stanford University, Stanford, California 94309, and Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim, Germany
| | - Thorsten Glaser
- Fakultät für Chemie, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany, Stanford Synchrotron Radiation Laboratory, SLAC, Stanford University, Stanford, California 94309, and Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim, Germany
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81
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Thibon A, Bartoli JF, Guillot R, Sainton J, Martinho M, Mansuy D, Banse F. Non-heme iron polyazadentate complexes as catalysts for aromatic hydroxylation by H2O2: Particular efficiency of tetrakis(2-pyridylmethyl)ethylenediamine–iron(II) complexes. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.molcata.2008.03.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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82
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Groni S, Dorlet P, Blain G, Bourcier S, Guillot R, Anxolabéhère-Mallart E. Reactivity of an Aminopyridine [LMnII]2+ Complex with H2O2. Detection of Intermediates at Low Temperature. Inorg Chem 2008; 47:3166-72. [DOI: 10.1021/ic702238z] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Sihem Groni
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR CNRS 8182, Equipe de Chimie Inorganique, Université Paris XI, 91405 Orsay, France, Laboratoire du Stress Oxydant et Détoxication, URA CNRS 2096-IBITECS CEA Saclay, Bat. 532, 91191 Gif-sur-Yvette Cedex, France, Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR CNRS 8182, Université Paris XI, 91405 Orsay, France, and Ecole Polytechnique 91128 Palaiseau, France
| | - Pierre Dorlet
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR CNRS 8182, Equipe de Chimie Inorganique, Université Paris XI, 91405 Orsay, France, Laboratoire du Stress Oxydant et Détoxication, URA CNRS 2096-IBITECS CEA Saclay, Bat. 532, 91191 Gif-sur-Yvette Cedex, France, Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR CNRS 8182, Université Paris XI, 91405 Orsay, France, and Ecole Polytechnique 91128 Palaiseau, France
| | - Guillaume Blain
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR CNRS 8182, Equipe de Chimie Inorganique, Université Paris XI, 91405 Orsay, France, Laboratoire du Stress Oxydant et Détoxication, URA CNRS 2096-IBITECS CEA Saclay, Bat. 532, 91191 Gif-sur-Yvette Cedex, France, Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR CNRS 8182, Université Paris XI, 91405 Orsay, France, and Ecole Polytechnique 91128 Palaiseau, France
| | - Sophie Bourcier
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR CNRS 8182, Equipe de Chimie Inorganique, Université Paris XI, 91405 Orsay, France, Laboratoire du Stress Oxydant et Détoxication, URA CNRS 2096-IBITECS CEA Saclay, Bat. 532, 91191 Gif-sur-Yvette Cedex, France, Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR CNRS 8182, Université Paris XI, 91405 Orsay, France, and Ecole Polytechnique 91128 Palaiseau, France
| | - Régis Guillot
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR CNRS 8182, Equipe de Chimie Inorganique, Université Paris XI, 91405 Orsay, France, Laboratoire du Stress Oxydant et Détoxication, URA CNRS 2096-IBITECS CEA Saclay, Bat. 532, 91191 Gif-sur-Yvette Cedex, France, Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR CNRS 8182, Université Paris XI, 91405 Orsay, France, and Ecole Polytechnique 91128 Palaiseau, France
| | - Elodie Anxolabéhère-Mallart
- Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR CNRS 8182, Equipe de Chimie Inorganique, Université Paris XI, 91405 Orsay, France, Laboratoire du Stress Oxydant et Détoxication, URA CNRS 2096-IBITECS CEA Saclay, Bat. 532, 91191 Gif-sur-Yvette Cedex, France, Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR CNRS 8182, Université Paris XI, 91405 Orsay, France, and Ecole Polytechnique 91128 Palaiseau, France
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83
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Hirao H, Que L, Nam W, Shaik S. A Two-State Reactivity Rationale for Counterintuitive Axial Ligand Effects on the CH Activation Reactivity of Nonheme FeIVO Oxidants. Chemistry 2008; 14:1740-56. [DOI: 10.1002/chem.200701739] [Citation(s) in RCA: 180] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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84
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Lee SH, Han JH, Kwak H, Lee SJ, Lee EY, Kim HJ, Lee JH, Bae C, Lee SN, Kim Y, Kim C. Biomimetic hydrocarbon oxidation catalyzed by nonheme iron(III) complexes with peracids: evidence for an Fe(V)=O species. Chemistry 2008; 13:9393-8. [PMID: 17685379 DOI: 10.1002/chem.200700513] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Mononuclear nonheme iron(III) complexes of tetradentate ligands containing two deprotonated amide moieties, [Fe(Me(2)bpb)Cl(H(2)O)] (3 a) and [Fe(bpc)Cl(H(2)O)] (4 a), were prepared by substitution reactions involving the previously synthesized iron(III) complexes [Et(3)NH][Fe(Me(2)bpb)Cl(2)] (3) and [Et(3)NH][Fe(bpc)Cl(2)] (4). Complexes 3 a and 4 a were characterized by IR and elemental analysis, and complex 3 a also by X-ray crystallography. Nonheme iron(III) complexes 3, 3 a, 4, and 4 a catalyze olefin epoxidation and alcohol oxidation on treatment with m-chloroperbenzoic acid. Pairwise comparisons of the reactivity of these complexes revealed that the nature of the axial ligand (Cl(-) versus H(2)O) influences the yield of oxidation products, whereas an electronic change in the supporting chelate ligand has little effect. Hydrocarbon oxidation by these catalysts was proposed to involve an iron(V) oxo species which is formed on heterolytic O-O bond cleavage of an iron acylperoxo intermediate (FeOOC(O)R). Evidence for this iron(V) oxo species was derived from KIE (k(H)/k(D)) values, H(2) (18)O exchange experiments, and the use of peroxyphenylacetic acid (PPAA) as the peracid. Our results suggest that an Fe(V)=O moiety can form in a system wherein the supporting chelate ligand comprises a mixture of neutral and anionic nitrogen donors. This work is relevant to the chemistry of mononuclear nonheme iron enzymes that are proposed to oxidize organic substrates via reaction pathways involving high-valent iron oxo species.
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Affiliation(s)
- Sun Hwa Lee
- Department of Fine Chemistry and Eco-Product and Materials Education Center, Seoul National University of Technology, Seoul, Korea
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85
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Bruijnincx PCA, van Koten G, Klein Gebbink RJM. Mononuclear non-heme iron enzymes with the 2-His-1-carboxylate facial triad: recent developments in enzymology and modeling studies. Chem Soc Rev 2008; 37:2716-44. [DOI: 10.1039/b707179p] [Citation(s) in RCA: 412] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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86
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Decker A, Rohde JU, Klinker EJ, Wong SD, Que L, Solomon EI. Spectroscopic and quantum chemical studies on low-spin FeIV=O complexes: Fe-O bonding and its contributions to reactivity. J Am Chem Soc 2007; 129:15983-96. [PMID: 18052249 DOI: 10.1021/ja074900s] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
High-valent FeIV=O species are key intermediates in the catalytic cycles of many mononuclear non-heme iron enzymes and have been structurally defined in model systems. Variable-temperature magnetic circular dichroism (VT-MCD) spectroscopy has been used to evaluate the electronic structures and in particular the Fe-O bonds of three FeIV=O (S = 1) model complexes, [FeIV(O)(TMC)(NCMe)]2+, [FeIV(O)(TMC)(OC(O)CF3)]+, and [FeIV(O)(N4Py)]2+. These complexes are characterized by their strong and covalent Fe-O pi-bonds. The MCD spectra show a vibronic progression in the nonbonding --> pi* excited state, providing the Fe-O stretching frequency and the Fe-O bond length in this excited state and quantifying the pi-contribution to the total Fe-O bond. Correlation of these experimental data to reactivity shows that the [FeIV(O)(N4Py)]2+ complex, with the highest reactivity toward hydrogen-atom abstraction among the three, has the strongest Fe-O pi-bond. Density functional calculations were correlated to the data and support the experimental analysis. The strength and covalency of the Fe-O pi-bond result in high oxygen character in the important frontier molecular orbitals (FMOs) for this reaction, the unoccupied beta-spin d(xz/yz) orbitals, that activates these for electrophilic attack. An extension to biologically relevant FeIV=O (S = 2) enzyme intermediates shows that these can perform electrophilic attack reactions along the same mechanistic pathway (pi-FMO pathway) with similar reactivity but also have an additional reaction channel involving the unoccupied alpha-spin d(z2) orbital (sigma-FMO pathway). These studies experimentally probe the FMOs involved in the reactivity of FeIV=O (S = 1) model complexes resulting in a detailed understanding of the Fe-O bond and its contributions to reactivity.
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Affiliation(s)
- Andrea Decker
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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87
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Abstract
Oxoiron(IV) species are often implicated in the catalytic cycles of oxygen-activating non-heme iron enzymes. The paucity of suitable model complexes stimulated us to fill this void, and our synthetic efforts have afforded a number of oxoiron(IV) complexes. This Account provides a chronological perspective of the observations that contributed to the generation of the first non-heme iron(IV)-oxo complexes in high yield and summarizes their salient properties to date.
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Affiliation(s)
- Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, USA
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88
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Nam W. High-valent iron(IV)-oxo complexes of heme and non-heme ligands in oxygenation reactions. Acc Chem Res 2007; 40:522-31. [PMID: 17469792 DOI: 10.1021/ar700027f] [Citation(s) in RCA: 909] [Impact Index Per Article: 53.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
High-valent iron(IV)-oxo species have been implicated as the key reactive intermediates in the catalytic cycles of dioxygen activation by heme and non-heme iron enzymes. Our understanding of the enzymatic reactions has improved greatly via investigation of spectroscopic and chemical properties of heme and non-heme iron(IV)-oxo complexes. In this Account, reactivities of synthetic iron(IV)-oxo porphyrin pi-cation radicals and mononuclear non-heme iron(IV)-oxo complexes in oxygenation reactions have been discussed as chemical models of cytochrome P450 and non-heme iron enzymes. These results demonstrate how mechanistic developments in biomimetic research can help our understanding of dioxygen activation and oxygen atom transfer reactions in nature.
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Affiliation(s)
- Wonwoo Nam
- Department of Chemistry, Division of Nano Sciences, and Center for Biomimetic Systems, Ewha Womans University, Seoul 120-750, Korea.
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89
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de Visser SP, Oh K, Han AR, Nam W. Combined experimental and theoretical study on aromatic hydroxylation by mononuclear nonheme iron(IV)-oxo complexes. Inorg Chem 2007; 46:4632-41. [PMID: 17444641 DOI: 10.1021/ic700462h] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The hydroxylation of aromatic compounds by mononuclear nonheme iron(IV)-oxo complexes, [FeIV(Bn-tpen)(O)]2+ (Bn-tpen=N-benzyl-N,N',N'-tris(2-pyridylmethyl)ethane-1,2-diamine) and [FeIV(N4Py)(O)]2+ (N4Py=N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine), has been investigated by a combined experimental and theoretical approach. In the experimental work, we have performed kinetic studies of the oxidation of anthracene with nonheme iron(IV)-oxo complexes generated in situ, thereby determining kinetic and thermodynamic parameters, a Hammett rho value, and a kinetic isotope effect (KIE) value. A large negative Hammett rho value of -3.9 and an inverse KIE value of 0.9 indicate that the iron-oxo group attacks the aromatic ring via an electrophilic pathway. By carrying out isotope labeling experiments, the oxygen in oxygenated products was found to derive from the nonheme iron(IV)-oxo species. In the theoretical work, we have conducted density functional theory (DFT) calculations on the hydroxylation of benzene by [FeIV(N4Py)(O)]2+. The calculations show that the reaction proceeds via two-state reactivity patterns on competing triplet and quintet spin states via an initial rate determining electrophilic substitution step. In analogy to heme iron(IV)-oxo catalysts, the ligand is noninnocent and actively participates in the reaction mechanism by reshuttling a proton from the ipso position to the oxo group. Calculated kinetic isotope effects of C6H6 versus C6D6 confirm an inverse isotope effect for the electrophilic substitution pathway. Based on the experimental and theoretical results, we have concluded that the aromatic ring oxidation by mononuclear nonheme iron(IV)-oxo complexes does not occur via a hydrogen atom abstraction mechanism but involves an initial electrophilic attack on the pi-system of the aromatic ring to produce a tetrahedral radical or cationic sigma-complex.
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Affiliation(s)
- Sam P de Visser
- Department of Chemistry, Division of Nano Sciences, and Center for Biomimetic Systems, Ewha Womans University, Seoul 120-750, Korea.
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90
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Groni S, Blain G, Guillot R, Policar C, Anxolabéhère-Mallart E. Reactivity of MnIIwith Superoxide. Evidence for a [MnIIIOO]+Unit by Low-Temperature Spectroscopies. Inorg Chem 2007; 46:1951-3. [PMID: 17311375 DOI: 10.1021/ic062063+] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Manganese superoxide dismutase cycles between the MnIII and MnII states to produce oxygen and hydrogen peroxide from superoxide. The formation of an adduct has been suggested, but its nature remains questionable because both [MnIIOO-] and [MnIIIOO2-] redox states have been proposed. Study of the reactivity of superoxide with manganese complexes is of current interest. The reaction of [(L)MnII]2+ [L = N-methyl-N,N',N'-tris(2-pyridylmethyl)ethane-1,2-diamine] with potassium superoxide has been investigated at low temperature in an anhydrous solvent using various techniques. Upon the addition of ca. 2 equiv of potassium superoxide, the [(L)MnII]2+ colorless solution turned blue and the UV-vis spectrum displayed a band at 590 nm (165 M(-1) cm(-1)) and a shoulder at 430 nm (100 M(-1) cm(-1)). Electrospray ionization mass spectrometry showed a peak (m/z = 434.1) assigned to [(L)MnO2]+. The X-band electron paramagnetic resonance spectrum parallel mode displayed a six-line signal separated by 6.6 mT and centered at 86 mT (g = 8.1). These results support the formation of an [MnIIIOO]+ adduct.
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Affiliation(s)
- Sihem Groni
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, UMR 8182, Université Paris XI, 91405 Orsay, France
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91
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Nehru K, Seo MS, Kim J, Nam W. Oxidative N-Dealkylation Reactions by Oxoiron(IV) Complexes of Nonheme and Heme Ligands. Inorg Chem 2006; 46:293-8. [PMID: 17198439 DOI: 10.1021/ic0614014] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nonheme and heme iron monooxygenases participate in oxidative N-dealkylation reactions in nature, and high-valent oxoiron(IV) species have been invoked as active oxidants that effect the oxygenation of organic substrates. The present study describes the first example of the oxidative N-dealkylation of N,N-dialkylamines by synthetic nonheme oxoiron(IV) complexes and the reactivity comparisons of nonheme and heme oxoiron(IV) complexes. Detailed mechanistic studies were performed with various N,N-dialkylaniline substrates such as para-substituted N,N-dimethylanilines, para-chloro-N-ethyl-N-methylaniline, para-chloro-N-cyclopropyl-N-isopropylaniline, and deuteriated N,N-dimethylanilines. The results of a linear free-energy correlation, inter- and intramolecular kinetic isotope effects, and product analysis studied with the mechanistic probes demonstrate that the oxidative N-dealkylation reactions by nonheme and heme oxoiron(IV) complexes occur via an electron transfer-proton transfer (ET-PT) mechanism.
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Affiliation(s)
- Kasi Nehru
- Department of Chemistry, Division of Nano Sciences, and Center for Biomimetic Systems, Ewha Womans University, Seoul 120-750, Korea
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92
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Eckert NA, Vaddadi S, Stoian S, Lachicotte RJ, Cundari TR, Holland PL. Coordination-Number Dependence of Reactivity in an Imidoiron(III) Complex. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200601927] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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93
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Eckert NA, Vaddadi S, Stoian S, Lachicotte RJ, Cundari TR, Holland PL. Coordination-Number Dependence of Reactivity in an Imidoiron(III) Complex. Angew Chem Int Ed Engl 2006; 45:6868-71. [PMID: 16991160 DOI: 10.1002/anie.200601927] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Nathan A Eckert
- Department of Chemistry, University of Rochester, NY 14627, USA
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94
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Structure and Properties of a Nonheme Pentacoordinate Iron(II) Complex with a Macrocyclic Triazapyridinophane Ligand. B KOREAN CHEM SOC 2006. [DOI: 10.5012/bkcs.2006.27.8.1140] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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95
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Sastri CV, Oh K, Lee YJ, Seo MS, Shin W, Nam W. Oxygen-Atom Transfer between Mononuclear Nonheme Iron(IV)–Oxo and Iron(II) Complexes. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200504422] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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96
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Sastri CV, Oh K, Lee YJ, Seo MS, Shin W, Nam W. Oxygen-Atom Transfer between Mononuclear Nonheme Iron(IV)–Oxo and Iron(II) Complexes. Angew Chem Int Ed Engl 2006; 45:3992-5. [PMID: 16688689 DOI: 10.1002/anie.200504422] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Chivukula V Sastri
- Department of Chemistry, Division of Nano Sciences, Center for Biomimetic Systems, Ewha Womans University, Seoul 120-750, Korea.
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97
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Terner J, Palaniappan V, Gold A, Weiss R, Fitzgerald MM, Sullivan AM, Hosten CM. Resonance Raman spectroscopy of oxoiron(IV) porphyrin π-cation radical and oxoiron(IV) hemes in peroxidase intermediates. J Inorg Biochem 2006; 100:480-501. [PMID: 16513173 DOI: 10.1016/j.jinorgbio.2006.01.008] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Accepted: 01/04/2006] [Indexed: 11/15/2022]
Abstract
The catalytic cycle intermediates of heme peroxidases, known as compounds I and II, have been of long standing interest as models for intermediates of heme proteins, such as the terminal oxidases and cytochrome P450 enzymes, and for non-heme iron enzymes as well. Reports of resonance Raman signals for compound I intermediates of the oxo-iron(IV) porphyrin pi-cation radical type have been sometimes contradictory due to complications arising from photolability, causing compound I signals to appear similar to those of compound II or other forms. However, studies of synthetic systems indicated that protein based compound I intermediates of the oxoiron(IV) porphyrin pi-cation radical type should exhibit vibrational signatures that are different from the non-radical forms. The compound I intermediates of horseradish peroxidase (HRP), and chloroperoxidase (CPO) from Caldariomyces fumago do in fact exhibit unique and characteristic vibrational spectra. The nature of the putative oxoiron(IV) bond in peroxidase intermediates has been under discussion in the recent literature, with suggestions that the Fe(IV)O unit might be better described as Fe(IV)-OH. The generally low Fe(IV)O stretching frequencies observed for proteins have been difficult to mimic in synthetic ferryl porphyrins via electron donation from trans axial ligands alone. Resonance Raman studies of iron-oxygen vibrations within protein species that are sensitive to pH, deuteration, and solvent oxygen exchange, indicate that hydrogen bonding to the oxoiron(IV) group within the protein environment contributes to substantial lowering of Fe(IV)O frequencies relative to those of synthetic model compounds.
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Affiliation(s)
- James Terner
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284-2006, USA.
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98
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Shan X, Que L. High-valent nonheme iron-oxo species in biomimetic oxidations. J Inorg Biochem 2006; 100:421-33. [PMID: 16530841 DOI: 10.1016/j.jinorgbio.2006.01.014] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Accepted: 01/04/2006] [Indexed: 10/24/2022]
Abstract
High valent iron-oxo species are often invoked as the key oxidizing agents in the catalytic cycles of oxygen activating nonheme iron enzymes, and three of these intermediates have in fact been characterized. To gain further insight into such species, a number of biomimetic complexes have been designed and investigated as functional models for these enzymes. Progress since 2000 is summarized in this review. Many of the model complexes discussed in this review carry out oxidative transformations of relevance to the enzymatic reactions; however, the participation of a high-valent iron-oxo species (Fe(IV)O or Fe(V)O) can only be inferred. Arguments in support of a metal-based oxidant (rather than an oxygen radical species) usually hinge on the high conversion for the transformation and the nature of the reaction products, as well as the incorporation of label into these products from H(2)(18)O or related species. Within this time period, the first bona fide nonheme Fe(IV)O complexes have been generated and identified spectroscopically, three of which are crystallographically characterized. Taken together, these studies emphasize the important role the supporting polydentate ligand plays in eliciting the desired high-valent iron-oxo chemistry.
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Affiliation(s)
- Xiaopeng Shan
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455, USA
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