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Zaitseva SV, Zdanovich SA, Kudrik EV, Koifman OI. Coordination properties of μ-carbidodimeric iron(IV) 2,3,7,8,12,13,17,18-octapropyltetraazaporphyrinate and 5,10,15,20-tetraphenylporphyrinate in reactions with nitrogen-containing bases. RUSS J INORG CHEM+ 2017. [DOI: 10.1134/s0036023617090194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Ide Y, Murai N, Ishimae H, Suzuki M, Mori S, Takahashi M, Nakamura M, Yoshino K, Ikeue T. Spin-crossover between high-spin (S = 5/2) and low-spin (S = 1/2) states in six-coordinate iron(iii) porphyrin complexes having two pyridine-N oxide derivatives. Dalton Trans 2016; 46:242-249. [PMID: 27924994 DOI: 10.1039/c6dt03859j] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In contrast to the general tendency that six coordinate iron(iii) porphyrin complexes with neutral oxygen ligands adopt a high-spin state in a wide range of temperature, some complexes with substituted pyridine N-oxides have exhibited spin-crossover from high-spin to low-spin states with decreasing temperature both in solution and in the solid state.
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Affiliation(s)
- Yuki Ide
- Department of Chemistry, Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.
| | - Nami Murai
- Department of Chemistry, Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.
| | - Hiroki Ishimae
- Department of Chemistry, Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.
| | - Masaaki Suzuki
- Department of Chemistry, Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.
| | - Shigeki Mori
- Advanced Research Support Center, Ehime University, 2-5, Bunkyo-cho, Matsuyama, 790-8577, Japan
| | - Masashi Takahashi
- Department of Chemistry, Faculty of Science, Toho University, Funabashi 274-8510, Japan
| | - Mikio Nakamura
- Department of Chemistry, Faculty of Science, Toho University, Funabashi 274-8510, Japan
| | - Katsumi Yoshino
- Shimane Institute for Industrial Technology, 1 Hokuryo, Matsue, Shimane 690-0816, Japan
| | - Takahisa Ikeue
- Department of Chemistry, Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.
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Zaitseva SV, Zdanovich SA, Tyulyaeva EY, Grishina ES, Koifman OI. Reduction of (chloro)-μ-nitrido-bis[(tetra-tert-butyl-phthalocyaninato)iron(IV)] with organic N-bases. J PORPHYR PHTHALOCYA 2016. [DOI: 10.1142/s1088424616500474] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The interaction of (chloro)-[Formula: see text]-nitrido-bis[(tetra-tert-butyl-phthalocyaninato)iron(IV)] Cl(FePc)2N with organic [Formula: see text]-bases L as electron–donors (L [Formula: see text] diethylamine, imidazole, 1-methylimidazole, 2-methylimidazole) with the formation of one-electron reduced species (L)PcFe[Formula: see text]–N[Formula: see text]Fe[Formula: see text]Pc(L) was investigated in benzene at 298 K by UV-visible spectroscopy. The reaction was established to be stepwise process including fast reversible axial binding of two substrate molecules onto iron cations followed by slow one-electron metal-centered reduction. The results of IR, ESI-MS and EPR study support the formation of final product with Fe[Formula: see text]–N[Formula: see text]Fe[Formula: see text] unit and two substrate molecules in the first coordination sphere. The reaction kinetics was studied, the pre-equilibrium constants [Formula: see text] and rate constants [Formula: see text] were obtained. The [Formula: see text] and [Formula: see text] values were found to be linearly correlated with basicity of substrates p[Formula: see text]. The possibility of the transition Fe[Formula: see text] Fe[Formula: see text] is promoted by electron–donor properties of substrate combined with the presence of both electron-rich macrocycle and [Formula: see text]-backdonation Fe [Formula: see text] N[Formula: see text].
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Affiliation(s)
- Svetlana V. Zaitseva
- G. A. Krestov Institute of Solution Chemistry of the Russian Academy of Science, Akademicheskaya St. 1, Ivanovo 153045, Russian Federation
| | - Sergei A. Zdanovich
- G. A. Krestov Institute of Solution Chemistry of the Russian Academy of Science, Akademicheskaya St. 1, Ivanovo 153045, Russian Federation
| | - Elena Y. Tyulyaeva
- G. A. Krestov Institute of Solution Chemistry of the Russian Academy of Science, Akademicheskaya St. 1, Ivanovo 153045, Russian Federation
| | - Ekaterina S. Grishina
- State University of Chemistry and Technology, Sheremetevskiyi Str. 7, Ivanovo 153000, Russian Federation
| | - Oskar I. Koifman
- G. A. Krestov Institute of Solution Chemistry of the Russian Academy of Science, Akademicheskaya St. 1, Ivanovo 153045, Russian Federation
- State University of Chemistry and Technology, Sheremetevskiyi Str. 7, Ivanovo 153000, Russian Federation
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Xu N, Christian JH, Dalal NS, Abucayon EG, Lingafelt C, Powell DR, Richter-Addo GB. Six-coordinate ferric porphyrins containing bidentate N-t-butyl-N-nitrosohydroxylaminato ligands: structure, magnetism, IR spectroelectrochemisty, and reactivity. Dalton Trans 2015; 44:20121-30. [PMID: 26530148 DOI: 10.1039/c5dt03074a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
NONOates (diazeniumdiolates) containing the [X{N2O2}](-) functional group are frequently employed as nitric oxide (NO) donors in biology, and some NONOates have been shown to bind to metalloenzymes. We report the preparation, crystal structures, detailed magnetic behavior, redox properties, and reactivities of the first isolable alkyl C-NONOate complexes of heme models, namely (OEP)Fe(η(2)-ON(t-Bu)NO) (1) and (TPP)Fe(η(2)-ON(t-Bu)NO) (2) (OEP = octaethylporphyrinato dianion, TPP = tetraphenylporphyrinato dianion). The compounds display the unusual NONOate O,O-bidentate binding mode for porphyrins, resulting in significant apical Fe displacements (+0.60 Å for 1, and +0.69 Å for 2) towards the axial ligands. Magnetic susceptibility and magnetization measurements made from 1.8-300 K at magnetic fields from 0.02 to 5 T, yielded magnetic moments of 5.976 and 5.974 Bohr magnetons for 1 and 2, respectively, clearly identifying them as high-spin (S = 5/2) ferric compounds. Variable-frequency (9.4 GHz and 34.5 GHz) EPR measurements, coupled with computer simulations, confirmed the magnetization results and yielded more precise values for the spin Hamiltonian parameters: g(avg) = 2.00 ± 0.03, |D| = 3.89 ± 0.09 cm(-1), and E/D = 0.07 ± 0.01 for both compounds, where D and E are the axial and rhombic zero-field splittings. IR spectroelectrochemistry studies reveal that the first oxidations of these compounds occur at the porphyrin macrocycles and not at the Fe-NONOate moieties. Reactions of 1 and 2 with a histidine mimic (1-methylimidazole) generate RNO and NO, both of which may bind to the metal center if sterics allow, as shown by a comparative study with the Cupferron complex (T(p-OMe)PP)Fe(η(2)-ON(Ph)NO). Protonation of 1 and 2 yields N2O as a gaseous product, presumably from the initial generation of HNO that dimerizes to the observed N2O product.
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Affiliation(s)
- Nan Xu
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA. and Division of Mathematics and Natural Sciences, Penn State Altoona, 3000 Ivyside Park, Altoona, PA 16601, USA.
| | - Jonathan H Christian
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, FL 32306, USA.
| | - Naresh S Dalal
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, FL 32306, USA.
| | - Erwin G Abucayon
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA.
| | - Colin Lingafelt
- Division of Mathematics and Natural Sciences, Penn State Altoona, 3000 Ivyside Park, Altoona, PA 16601, USA.
| | - Douglas R Powell
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA.
| | - George B Richter-Addo
- Department of Chemistry and Biochemistry, University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019, USA.
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Sakow D, Baabe D, Böker B, Burghaus O, Funk M, Kleeberg C, Menzel D, Pietzonka C, Bröring M. Iron 10-Thiacorroles: Bioinspired Iron(III) Complexes with an Intermediate Spin (S=3/2) Ground State. Chemistry 2014; 20:2913-24. [DOI: 10.1002/chem.201303786] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 10/17/2013] [Indexed: 11/07/2022]
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Nakamura M, Ikezaki A, Takahashi M. Metal-Porphyrin Orbital Interactions in Paramagnetic Iron Complexes Having Planar and Deformed Porphyrin Ring. J CHIN CHEM SOC-TAIP 2012. [DOI: 10.1002/jccs.201200474] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Rury AS, Goodrich LE, Galinato MGI, Lehnert N, Sension RJ. Ligand Recruitment and Spin Transitions in the Solid-State Photochemistry of Fe(III)TPPCl. J Phys Chem A 2012; 116:8321-33. [DOI: 10.1021/jp304667t] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aaron S. Rury
- Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109,
United States
- Department
of Chemistry, University of Michigan, Ann
Arbor, Michigan 48109,
United States
| | - Lauren E. Goodrich
- Department
of Chemistry, University of Michigan, Ann
Arbor, Michigan 48109,
United States
| | - Mary Grace I. Galinato
- School of Science, Penn State Erie, The Behrend College, Erie, Pennsylvania
16563, United States
| | - Nicolai Lehnert
- Department
of Chemistry, University of Michigan, Ann
Arbor, Michigan 48109,
United States
| | - Roseanne J. Sension
- Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109,
United States
- Department
of Chemistry, University of Michigan, Ann
Arbor, Michigan 48109,
United States
- Department
of Physics, University of Michigan, Ann
Arbor, Michigan 48109,
United States
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Ikeue T, Kurahashi S, Handa M, Sugimori T, Nakamura M. Electronic structure of five- and six-coordinate iron(III) tetraazaporphyrin complexes: pyrrole-Cαchemical shift as a useful probe. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424608000418] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Electronic structure of a series of five-coordinate Fe ( OArTAzP ) X ( OAr = octaaryltetraazaporphyrin , X = Cl-, Br-, I-; Ar = 4-tert-butylphenyl) have been examined on the basis of1H NMR,13C NMR, and EPR spectroscopy as well as SQUID magnetometry. These complexes adopt the intermediate-spin state as in the case of analogous complexes reported by Fitzgerald et al. (Inorg. Chem. 1992; 31: 2006-2013) and Stuzhin et al. (Inorg. Chim. Acta 1995; 236: 131-139). The13C NMR studies using13C -enriched complexes at the pyrrole α positions have revealed that the pyrrole- Cαsignals appear at extraordinary upfield positions, i.e. -130 to -250 ppm at 273 K, due to the dz2-a2 uand dπ-3 eginteractions. The Curie plots of the pyrrole- Cαsignals have further revealed that the iodide complex adopts a much purer intermediate-spin state than the bromide and chloride complexes. In contrast to the case of Fe ( OArTAzP ) X , six-coordinate [ Fe ( OArTAzP )( CN )2]-showed the pyrrole- Cαsignal at 47 ppm at 273 K, which indicates that the complex adopts the low-spin state with the ( dxy)2( dxz, dyz)3electron configuration. Thus, the13C NMR chemical shift of the pyrrole- Cαsignal turns out to be quite a good probe to elucidate the spin state and electron configuration of iron(III) tetraazaporphyrins, where the1H NMR spectroscopy is less useful because of the absence of the hydrogen atoms as well as the alkyl or aryl groups directly attached to the meso positions.
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Affiliation(s)
- Takahisa Ikeue
- Department of Chemistry, Faculty of Material Science, Shimane University, Matsue 690-8504, Japan
| | - Satoshi Kurahashi
- Department of Chemistry, Faculty of Material Science, Shimane University, Matsue 690-8504, Japan
| | - Makoto Handa
- Department of Chemistry, Faculty of Material Science, Shimane University, Matsue 690-8504, Japan
| | - Tamotu Sugimori
- Division of Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
| | - Mikio Nakamura
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
- Research Center for Materials with Integrated Properties, Toho University, Funabashi 274-8510, Japan
- Division of Chemistry, Graduate School of Science, Toho University, Funabashi 274-8510, Japan
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Ikeue T, Handa M, Chamberlin A, Ghosh A, Ongayi O, Vicente MGH, Ikezaki A, Nakamura M. Benzoannelation Stabilizes the dxy1 State of Low-Spin Iron(III) Porphyrinates. Inorg Chem 2011; 50:3567-81. [DOI: 10.1021/ic1024873] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Takahisa Ikeue
- Department of Chemistry, Faculty of Material Science, Shimane University, 1060 Nishikawatsu-cho, Matsue-shi, Shimane 690-8504, Japan
| | - Makoto Handa
- Department of Chemistry, Faculty of Material Science, Shimane University, 1060 Nishikawatsu-cho, Matsue-shi, Shimane 690-8504, Japan
| | - Adam Chamberlin
- Department of Chemistry and the Center for Theoretical and Computational Chemistry, University of Tromso, Breivika, N-9037 Tromso, Norway
| | - Abhik Ghosh
- Department of Chemistry and the Center for Theoretical and Computational Chemistry, University of Tromso, Breivika, N-9037 Tromso, Norway
| | - Owendi Ongayi
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - M. Graça H. Vicente
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Akira Ikezaki
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
| | - Mikio Nakamura
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
- Division of Chemistry, Graduate School of Science, Toho University, Funabashi 274-8510, Japan
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Ikezaki A, Nakamura M. Formation and characterization of a six-coordinate iron(iii) complex with the most ruffled porphyrin ring. Dalton Trans 2011; 40:3455-8. [DOI: 10.1039/c1dt10042d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Patra R, Bhowmik S, Ghosh SK, Rath SP. Effects of axial pyridine coordination on a saddle-distorted porphyrin macrocycle: stabilization of hexa-coordinated high-spin Fe(iii) and air-stable low-spin iron(ii) porphyrinates. Dalton Trans 2010; 39:5795-806. [DOI: 10.1039/b924742d] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ikezaki A, Ohgo Y, Nakamura M. NMR studies on the electronic structure of one-electron oxidized complexes of iron(III) porphyrinates. Coord Chem Rev 2009. [DOI: 10.1016/j.ccr.2009.01.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ikezaki A, Takahashi M, Nakamura M. Models for Cytochromes c′: Observation of an Extremely Labile Spin State in Monoimidazole Complexes of Saddle-Shaped Iron(III) Porphyrinates. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200902224] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Ikezaki A, Takahashi M, Nakamura M. Models for Cytochromes c′: Observation of an Extremely Labile Spin State in Monoimidazole Complexes of Saddle-Shaped Iron(III) Porphyrinates. Angew Chem Int Ed Engl 2009; 48:6300-3. [DOI: 10.1002/anie.200902224] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Ling Y, Zhang Y. Mössbauer, NMR, geometric, and electronic properties in S = 3/2 iron porphyrins. J Am Chem Soc 2009; 131:6386-8. [PMID: 19415933 PMCID: PMC2730173 DOI: 10.1021/ja9006723] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Iron porphyrins with the intermediate spin S = 3/2 or admixed with S = 5/2 or 1/2 are models for a number of heme protein systems, including cytochromes c'. The (57)Fe Mossbauer quadrupole splittings and (1)H and (13)C NMR chemical shifts have been found to be useful probes of their electronic states. We present the results of the first successful quantum chemical calculations of the Mössbauer and NMR properties in various S = 3/2 iron porphyrin complexes, covering four-, five-, and six-coordinate states and three commonly seen porphyrin conformations: planar, ruffled, and saddled. Several interesting correlations among these useful experimental spectroscopic probes and geometric and electronic properties were discovered. These results should facilitate future investigations of related heme proteins and model systems.
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Affiliation(s)
- Yan Ling
- Departments of Chemistry and Biochemistry, University of Southern Mississippi, 118 College Drive #5043, Hattiesburg, MS 39406, USA
| | - Yong Zhang
- Departments of Chemistry and Biochemistry, University of Southern Mississippi, 118 College Drive #5043, Hattiesburg, MS 39406, USA
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Cheng RJ, Chao CW, Han YP, Chen YC, Ting CH. Saddle-shaped six-coordinate iron(iii) porphyrin complex with unusual intermediate-spin electronic structure. Chem Commun (Camb) 2009:2180-2. [DOI: 10.1039/b820443h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Patra R, Chaudhary A, Ghosh SK, Rath SP. Modulation of Metal Displacements in a Saddle Distorted Macrocycle: Synthesis, Structure, and Properties of High-Spin Fe(III) Porphyrins and Implications for the Hemoproteins. Inorg Chem 2008; 47:8324-35. [DOI: 10.1021/ic800944q] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Ranjan Patra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
| | - Arvind Chaudhary
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
| | - Sudip Kumar Ghosh
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
| | - Sankar Prasad Rath
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
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Eguchi H, Ohgo Y, Ikezaki A, Neya S, Nakamura M. Bis(1-methylimidazole) Complex of Iron(III) Oxypyriporphyrin Adopting an Intermediate-spin State. CHEM LETT 2008. [DOI: 10.1246/cl.2008.768] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Davydov R, Hoffman BM. EPR and ENDOR studies of Fe(II) hemoproteins reduced and oxidized at 77 K. J Biol Inorg Chem 2007; 13:357-69. [PMID: 18058139 DOI: 10.1007/s00775-007-0328-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Accepted: 11/14/2007] [Indexed: 11/24/2022]
Abstract
gamma-irradiation of frozen solutions of Fe(II) hemoproteins at 77 K generates both electron paramagnetic resonance (EPR) active singly reduced and oxidized heme centers trapped in the conformation of the Fe(II) precursors. The reduction products of pentacoordinate (S = 2) Fe(II) globins, peroxidases and cytochrome P450cam show EPR and electron-nuclear double resonance (ENDOR) spectra characteristic of (3d 7) Fe(I) species. In addition, cryoreduced Fe(II) alpha-chains of hemoglobin and myoglobin exhibit an S = 3/2 spin state produced by antiferromagnetic coupling between a porphyrin anion radical and pentacoordinate (S = 2) Fe(II). The spectra of cryoreduced forms of Fe(II) hemoglobin alpha-chains and deoxymyoglobin reveal that the Fe(II) precursors adopt multiple conformational substates. Reduction of hexacoordinate Fe(II) cytochrome c and cytochrome b5 as well as carboxy complexes of deoxyglobins produces only Fe(II) porphyrin pi-anion radical species. The low-valent hemoprotein intermediates produced by cryoreduction convert to the Fe(II) states at T > 200 K. Cryogenerated Fe(III) cytochrome c and cytochrome b5 have spectra similar to these for the resting Fe(III) states, whereas the spectra of the products of cryooxidation of pentacoordinate Fe(II) globins and peroxidases are different. Cryooxidation of CO-Fe(II) globins generates Fe(III) hemes with quantum-mechanically admixed S = 3/2, 5/2 ground states. The trapped Fe(III) species relax to the equilibrium ferric states upon annealing at T > 190 K. Both cryooxidized and reduced centers provide very sensitive EPR/ENDOR structure probes of the EPR-silent Fe(II) state.
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Affiliation(s)
- Roman Davydov
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Tech K148, Evanston, IL 60208-3113, USA.
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Ohgo Y, Hoshino A, Uekusa H, Nakamura M. Peculiar sandwich-like π–π interaction regulating the nonplanarity of the model heme crystals. INORG CHEM COMMUN 2006. [DOI: 10.1016/j.inoche.2006.07.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Ikezaki A, Nakamura M, Juillard S, Simonneaux G. 13C NMR Studies of the Electronic Structure of Low-Spin Iron(III) Tetraphenylchlorin Complexes. Inorg Chem 2006; 45:6728-39. [PMID: 16903729 DOI: 10.1021/ic060508o] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of low-spin six-coordinate (tetraphenylchlorinato)iron(III) complexes [Fe(TPC)(L)2]+/- (L = 1-MeIm, CN-, 4-CNPy, and (t)BuNC) have been prepared, and their (13)C NMR spectra have been examined to reveal the electronic structure. These complexes exist as the mixture of the two isomers with the (d(xy))2(d(xz), d(yz))3 and (d(xz), d(yz))4(d(xy))1 ground states. Contribution of the (d(xz), d(yz))4(d(xy))1 isomer has increased as the axial ligand changes from 1-MeIm, to CN(-) (in CD2Cl2 solution), CN- (in CD(3)OD solution), and 4-CNPy, and then to tBuNC as revealed by the meso and pyrroline carbon chemical shifts; the meso carbon signals at 146 and -19 ppm in [Fe(TPC)(1-MeIm)2]+ shifted to 763 and 700 ppm in [Fe(TPC)(tBuNC)2]+. In the case of the CN- complex, the population of the (d(xz), d(yz))4(d(xy))1 isomer has increased to a great extent when the solvent is changed from CD2Cl2 to CD3OD. The result is ascribed to the stabilization of the d(xz) and d(yz) orbitals of iron(III) caused by the hydrogen bonding between methanol and the coordinated cyanide ligand. Comparison of the 13C NMR data of the TPC complexes with those of the TPP, OEP, and OEC complexes has revealed that the populations of the (d(xz), d(yz))4(d(xy))1 isomer in TPC complexes are much larger than those in the corresponding TPP, OEC, and OEP complexes carrying the same axial ligands.
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Affiliation(s)
- Akira Ikezaki
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
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Weiss R, Gold A, Terner J. Cytochromes c‘: Biological Models for the S = 3/2,5/2 Spin-State Admixture? Chem Rev 2006; 106:2550-79. [PMID: 16771459 DOI: 10.1021/cr040416l] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Raymond Weiss
- Laboratoire de Chimie Supramoléculaires, Institut de Science et d'Ingénierie Supramoléculaires, Université Louis Pasteur de Strasbourg, 8 Allée Gaspard Monge, B.P.70028, F-67083 Strasbourg Cedex, France
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Ohgo Y, Chiba Y, Hashizume D, Uekusa H, Ozeki T, Nakamura M. Novel spin transition between S = 5/2 and S = 3/2 in highly saddled iron(III) porphyrin complexes at extremely low temperatures. Chem Commun (Camb) 2006:1935-7. [PMID: 16767241 DOI: 10.1039/b601412g] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel spin transition between S = 5/2 and S = 3/2 has been observed for the first time in five-coordinate, highly saddled iron(III) porphyrinates by EPR and SQUID measurements at extremely low temperatures.
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Affiliation(s)
- Yoshiki Ohgo
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan.
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27
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Higuchi M, Hitomi Y, Minami H, Tanaka T, Funabiki T. Correlation of Spin States and Spin Delocalization with the Dioxygen Reactivity of Catecholatoiron(III) Complexes. Inorg Chem 2005; 44:8810-21. [PMID: 16296836 DOI: 10.1021/ic051173y] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of catecholatoiron(III) complexes, [Fe(III)L(4Cl-cat)]BPh4 (L = (4-MeO)2TPA (1), TPA (2), (4-Cl)2TPA (3), (4-NO2)TPA (4), (4-NO2)2TPA (5); TPA = tris(pyridin-2-ylmethyl)amine; 4Cl-cat = 4-chlorocatecholate), have been characterized by magnetic susceptibility measurements and EPR, 1H NMR, and UV-vis-NIR spectroscopies to clarify the correlation of the spin delocalization on the catecholate ligand with the O2 reactivity as well as the spin-state dependence of the O2 reactivity. EPR spectra in frozen CH3CN at 123 K clearly showed that introduction of electron-withdrawing groups effectively shifts the spin equilibrium from a high-spin to a low-spin state. The effective magnetic moments determined by the Evans method in a CH3CN solution showed that 5 contains 36% of low-spin species at 243 K, while 1-4 are predominantly in a high-spin state. Evaluation of spin delocalization on the 4Cl-cat ligand by paramagnetic 1H NMR shifts revealed that the semiquinonatoiron(II) character is more significant in the low-spin species than in the high-spin species. The logarithm of the reaction rate constant is linearly correlated with the energy gap between the catecholatoiron(III) and semiquinonatoiron(II) states for the high-spin complexes 1-3, although complexes 4 and 5 deviate negatively from linearity. The lower reactivity of the low-spin complex, despite its higher spin density on the catecholate ligand compared with the high-spin analogues, suggests the involvement of the iron(III) center, rather than the catecholate ligand, in the reaction with O2.
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Affiliation(s)
- Masakazu Higuchi
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
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28
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Hoshino A, Ohgo Y, Nakamura M. Electronic Structures of Six-Coordinate Ferric Porphyrin Complexes with Weak Axial Ligands: Usefulness of 13C NMR Chemical Shifts. Inorg Chem 2005; 44:7333-44. [PMID: 16212360 DOI: 10.1021/ic0488942] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1H NMR, (13)C NMR, and EPR spectra of six-coordinate ferric porphyrin complexes [Fe(Por)L2]ClO4 with different porphyrin structures are presented, where porphyrins (Por) are planar 5,10,15,20-tetraphenylporphyrin (TPP), ruffled 5,10,15,20-tetraisopropylporphyrin (TiPrP), and saddled 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin (OETPP), and axial ligands (L) are weak oxygen ligands such as pyridine-N-oxide, substituted pyridine-N-oxide, DMSO, DMF, MeOH, THF, 2-MeTHF, and dioxane. These complexes exhibit the spin states ranging from an essentially pure high-spin (S = 5/2) to an essentially pure intermediate-spin (S = 3/2) state depending on the field strength of the axial ligands and the structure of the porphyrin rings. Reed and Guiset reported that the pyrrole-H chemical shift is a good probe to determine the spin state in the spin admixed S = 5/2,3/2 complexes (Reed, C. A.; Guiset, F. J. Am. Chem. Soc. 1996, 118, 3281-3282). In this paper, we report that the chemical shifts of the alpha- and beta-pyrrole carbons can also be good probes to determine the spin state because they have shown good correlation with those of the pyrrole-H or pyrrole-C(alpha). By putting the observed or assumed pyrrole-H or pyrrole-C(alpha) chemical shifts of the pure high-spin and pure intermediate-spin complexes into the correlation equations, we have estimated the carbon chemical shits of the corresponding complexes. The orbital interactions between iron(III) and porphyrin have been examined on the basis of these chemical shifts, from which we have found that both the d(xy)-a(2u) interaction in the ruffled Fe(T(i)PrP)L2+ and d(xy)-a(1u) interaction in the saddled Fe(OETPP)L2+ are quite weak in the high-spin and probably in the intermediate-spin complexes as well. Close inspection of the correlation lines has suggested that the electron configuration of an essentially pure intermediate-spin Fe(T(i)PrP)L2+ changes from (d(xy), d(yz))3(d(xy))1(d(z)2)1 to (d(xy))2(d(xz), d(yz))2(d(z)2)1 as the axial ligand (L) changes from DMF to MeOH, THF, 2-MeTHF, and then to dioxane. Although the DFT calculation has indicated that the highly saddled intermediate-spin Fe(OETPP)(THF)2+ should adopt (d(xy), d(yz))3(d(xy))1(d(z)2)1 rather than (d(xy))2(d(xz), d(yz))2(d(z)2)1 because of the strong d(xy)-a(1u) interaction (Cheng, R.-J.; Wang, Y.-K.; Chen, P.-Y.; Han, Y.-P.; Chang, C.-C. Chem. Commun. 2005, 1312-1314), our 13C NMR study again suggests that Fe(OETPP)(THF)2+ should be represented as (d(xy))2(d(xz), d(yz))2(d(z)2)1 because of the weak d(xy)-a(1u) interaction. The contribution of the S = 3/2 state in all types of the spin admixed S = 5/2,3/2 six-coordinate complexes has been determined on the basis of the (13)C NMR chemical shifts.
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Affiliation(s)
- Akito Hoshino
- Division of Biomolecular Science, Graduate School of Science, Toho University, Funabashi 274-8510, Japan
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Neya S, Chang CK, Okuno D, Hoshino T, Hata M, Funasaki N. Control of Iron(III) Spin-State in the Model Complexes of Azide Hemoprotein by Porphycene, Corrphycene, and Hemiporphycene Macrocycles. Inorg Chem 2005; 44:1193-5. [PMID: 15732955 DOI: 10.1021/ic048353c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Spin states of the iron(III) complexes of porphyrin, porphycene, hemiporphycene, and corrphycene bearing both 1-methylimidazole and azide as axial ligands were analyzed with infrared (IR) spectroscopy at 20 degrees C. The IR stretching band of coordinating azide split into two peaks around 2047 and 2017 cm(-1) reflecting an equilibrium between the high- (S = 5/2) and low- (S = 1/2) spin states. The high-spin fraction changed over a 0-90% range among the macrocycles, demonstrating that the tetrapyrrole array is essential to control the equilibrium.
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Affiliation(s)
- Saburo Neya
- Department of Physical Chemistry, Graduate School of Pharmaceutical Sciences, Chiba University, Inage-Yayoi, Chiba 263-8522, Japan.
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Sakai T, Ohgo Y, Hoshino A, Ikeue T, Saitoh T, Takahashi M, Nakamura M. Electronic Structures of Five-Coordinate Iron(III) Porphyrin Complexes with Highly Ruffled Porphyrin Ring. Inorg Chem 2004; 43:5034-43. [PMID: 15285680 DOI: 10.1021/ic049825q] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The spin states of the iron(III) complexes with a highly ruffled porphyrin ring, [Fe(TEtPrP)X] where X = F-, Cl-, Br-, I-, and ClO4(-), have been examined by 1H NMR, 13C NMR, EPR, and Mössbauer spectroscopy. While the F-, Cl-, and Br- complexes adopt a high-spin (S = 5/2) state, the I- complex exhibits an admixed intermediate-spin (S = 5/2, 3/2) state in CD2Cl2 solution. The I- complex shows, however, a quite pure high-spin state in toluene solution as well as in the solid. The results contrast those of highly saddled [Fe(OETPP)X] where the I- complex exhibits an essentially pure intermediate-spin state both in solution and in the solid. In contrast to the halide-ligated complexes, the ClO4(-) complex shows a quite pure intermediate-spin state. The 13C NMR spectra of [Fe(TEtPrP)ClO4] are characterized by the downfield and upfield shifts of the meso and pyrrole-alpha carbon signals, respectively: delta(meso) = +342 and delta(alpha-py) = -287 ppm at 298 K. The data indicate that the meso carbon atoms of [Fe(TEtPrP)ClO4] have considerable amounts of positive spin, which in turn indicate that the iron has an unpaired electron in the d(xy) orbital; the unpaired electron in the d(xy) orbital is delocalized to the meso positions due to the iron(d(xy))-porphyrin(a(2u)) interaction. Similar results have been obtained in analogous [Fe(TiPrP)X] though the intermediate-spin character of [Fe(TiPrP)X] is much larger than that of the corresponding [Fe(TEtPrP)X]. On the basis of these results, we have concluded that the highly ruffled intermediate-spin complexes such as [Fe(TEtPrP)ClO4] and [Fe(TiPrP)ClO4] adopt a novel (d(xz), d(yz))3(d(xy))1(d(z)(2)1 electron configuration; the electron configuration of the intermediate-spin complexes reported previously is believed to be (d(xy))2(d(xz)), d(yz))2(d(z)(2))1.
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Affiliation(s)
- Takanori Sakai
- Department of Chemistry, School of Medicine, Toho University, Tokyo 143-8540, Japan
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Yatsunyk LA, Walker FA. Structural, NMR, and EPR Studies of S = 1/2 and S = 3/2 Fe(III) Bis(4-Cyanopyridine) Complexes of Dodecasubstituted Porphyrins. Inorg Chem 2003; 43:757-77. [PMID: 14731040 DOI: 10.1021/ic035010q] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The NMR and EPR spectra for three complexes, iron(III) octamethyltetraphenylporphyrin bis(4-cyanopyridine) perchlorate, [FeOMTPP(4-CNPy)(2)]ClO(4), and its octaethyl- and tetra-beta,beta'-tetramethylenetetraphenylporphyrin analogues, [FeOETPP(4-CNPy)(2)]ClO(4) and [FeTC(6)TPP(4-CNPy)(2)]ClO(4), are presented. The crystal structures of two different forms of [FeOETPP(4-CNPy)(2)]ClO(4) and one form of [FeOMTPP(4-CNPy)(2)]ClO(4) are also reported. Attempts to crystallize [FeTC(6)TPP(4-CNPy)(2)]ClO(4) were not successful. The crystal structure of [FeOMTPP(4-CNPy)(2)]ClO(4) reveals a saddled porphyrin core, a small dihedral angle between the axial ligand planes, 64.3 degrees, and an unusually large tilt angle (24.4 degrees ) of one of the axial 4-cyanopyridine ligands with respect to the normal to the porphyrin mean plane. There are 4 and 2 independent molecules in the asymmetric units of [FeOETPP(4-CNPy)(2)]ClO(4) crystallized from CD(2)Cl(2)/dodecane (1-4) and CDCl(3)/cyclohexane (5-6), respectively. The geometries of the porphyrin cores in 1-6 vary from purely saddled to saddled with 15% ruffling admixture. In all structures, the Fe-N(p) distances (1.958-1.976 A) are very short due to strong nonplanar distortion of the porphyrin cores, while the Fe-N(ax) distances are relatively long ( approximately 2.2 A) compared to the same distances in S = (1)/(2) bis(pyridine)iron(III) porphyrin complexes. An axial EPR signal is observed (g( perpendicular ) = 2.49, g( parallel ) = 1.6) in frozen solutions of both [FeOMTPP(4-CNPy)(2)]ClO(4) and [FeTC(6)TPP(4-CNPy)(2)]ClO(4) at 4.2 K, indicative of the low spin (LS, S = (1)/(2)), (d(yz)d(xz))(4)(d(xy))(1) electronic ground state for these two complexes. In agreement with a recent publication (Ikeue, T.; Ohgo, Y.; Ongayi, O.; Vicente, M. G. H.; Nakamura, M. Inorg. Chem. 2003, 42, 5560-5571), the EPR spectra of [FeOETPP(4-CNPy)(2)]ClO(4) are typical of the S = (3)/(2) state, with g values of 5.21, 4.25, and 2.07. A small amount of LS species with g = 3.03 is also present. However, distinct from previous conclusions, large negative phenyl-H shift differences delta(m) - delta(o) and delta(m) - delta(p) in the (1)H NMR spectra indicate significant negative spin density at the meso-carbons, and the larger than expected positive average CH(2) shifts are also consistent with a significant population of the S = 2 Fe(II), S = (1)/(2) porphyrin pi-cation radical state, with antiferromagnetic coupling between the metal and porphyrin unpaired electrons. This is the first example of this type of porphyrin-to-metal electron transfer to produce a partial or complete porphyrinate radical state, with antiferromagnetic coupling between metal and macrocycle unpaired electrons in an iron porphyrinate. The kinetics of ring inversion were studied for the [FeOETPP(4-CNPy)(2)]ClO(4) complex using NOESY/EXSY techniques and for the [FeTC(6)TPP(4-CNPy)(2)]ClO(4) complex using DNMR techniques. For the former, the free energy of activation, deltaG, and rate of ring inversion in CD(2)Cl(2) extrapolated to 298 K are 63(2) kJ mol(-)(1) and 59 s(-)(1), respectively, while for the latter the rate of ring inversion at 298 K is at least 4.4 x 10(7) s(-)(1), which attests to the much greater flexibility of the TC(6)TPP ring. The NMR and EPR data are consistent with solution magnetic susceptibility measurements that show S = (3)/(2) in the temperature range from 320 to 180 K for [FeOETPP(4-CNPy)(2)](+), while both [FeOMTPP(4-CNPy)(2)](+) and [FeTC(6)TPP(4-CNPy)(2)](+) change their spin state from S = (3)/(2) at room temperature to mainly LS (S = (1)/(2)) upon cooling to 180 K.
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Affiliation(s)
- Liliya A Yatsunyk
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721-0041, USA
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