1
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Silver J, den Engelsen D, Al-Jaff G, Taies JA, Wilson MT, Fern GR. Protoporphyrin IX iron(II) revisited. An overview of the Mössbauer spectroscopic parameters of low-spin porphyrin iron(II) complexes. J Biol Inorg Chem 2024:10.1007/s00775-024-02075-9. [PMID: 39384634 DOI: 10.1007/s00775-024-02075-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2024] [Accepted: 09/19/2024] [Indexed: 10/11/2024]
Abstract
Mössbauer parameters of low-spin six-coordinate [Fe(II)(Por)L2] complexes (where Por is a synthetic porphyrin; L is a nitrogenous aliphatic, an aromatic base or a heterocyclic ligand, a P-bonding ligand, CO or CN) and low-spin [Fe(Por)LX] complexes (where L and X are different ligands) are reported. A known point charge calculation approach was extended to investigate how the axial ligands and the four porphyrinato-N atoms generate the observed quadrupole splittings (ΔEQ) for the complexes. Partial quadrupole splitting (p.q.s.) and partial chemical shifts (p.c.s.) values were derived for all the axial ligands, and porphyrins reported in the literature. The values for each porphyrin are different emphasising the importance/uniqueness of the [Fe(PPIX)] moiety, (which is ubiquitous in nature). This new analysis enabled the construction of figures relating p.c.s and p.q.s values. The relationships presented in the figures indicates that strong field ligands such as CO can, and do change the sign of the electric field gradient in the [Fe(II)(Por)L2] complexes. The limiting p.q.s. value a ligand can have and still form a six-coordinate low-spin [Fe(II)(Por)L2] complex is established. It is shown that the control the porphyrin ligands exert on the low-spin Fe(II) atom limits its bonding to a defined range of axial ligands; outside this range the spin state of the iron is unstable and five-coordinate high-spin complexes are favoured. Amongst many conclusions, it was found that oxygen cannot form a stable low-spin [Fe(II)(Por)L(O2)] complex and that oxy-haemoglobin is best described as an [Fe(III)(Por)L(O2-)] complex, the iron is ferric bound to the superoxide molecule.
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Affiliation(s)
- Jack Silver
- Department of Chemical Engineering, Wolfson Centre for Sustainable Materials Processing and Development, Brunel University of London, Kingston Lane, Uxbridge, Middlesex, UB8 3PH, UK
| | - Daniel den Engelsen
- Department of Chemical Engineering, Wolfson Centre for Sustainable Materials Processing and Development, Brunel University of London, Kingston Lane, Uxbridge, Middlesex, UB8 3PH, UK
| | - Golzar Al-Jaff
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
- Department of Chemistry, College of Education, Salahaddin University, Erbil, Iraq
| | - Jehad A Taies
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
- Depatment of Chemistry, College of Education for Pure Science, Ramedi, Iraq
| | - Michael T Wilson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, UK
| | - George R Fern
- Department of Chemical Engineering, Wolfson Centre for Sustainable Materials Processing and Development, Brunel University of London, Kingston Lane, Uxbridge, Middlesex, UB8 3PH, UK.
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2
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Kawamura A, Xie J, Boyn JN, Jesse KA, McNeece AJ, Hill EA, Collins KA, Valdez-Moreira JA, Filatov AS, Kurutz JW, Mazziotti DA, Anderson JS. Reversible Switching of Organic Diradical Character via Iron-Based Spin-Crossover. J Am Chem Soc 2020; 142:17670-17680. [PMID: 32948091 DOI: 10.1021/jacs.0c08307] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Airi Kawamura
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Jiaze Xie
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Jan-Niklas Boyn
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Kate A. Jesse
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Andrew J. McNeece
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Ethan A. Hill
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Kelsey A. Collins
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | | | - Alexander S. Filatov
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Josh W. Kurutz
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - David A. Mazziotti
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - John S. Anderson
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
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3
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Yao Z, Schulz CE, Zhan N, Li J. Iron(II) Bis(imidazole) Derivatives of a Binuclear Porphyrin Model: Crystal Structures and Mössbauer Properties. Inorg Chem 2017; 56:12615-12624. [DOI: 10.1021/acs.inorgchem.7b02092] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Zhen Yao
- College of Materials
Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Yanqi
Lake, Huairou District, Beijing 101408, China
| | - Charles E. Schulz
- Department of Physics, Knox College, Galesburg, Illinois 61401, United States
| | - Nana Zhan
- College of Materials
Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Yanqi
Lake, Huairou District, Beijing 101408, China
| | - Jianfeng Li
- College of Materials
Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Yanqi
Lake, Huairou District, Beijing 101408, China
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4
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Nasri S, Brahmi J, Turowska-Tyrk I, Schulz CE, Nasri H. Synthesis, UV-visible and Mössbauer spectroscopic studies and molecular structure of the low-spin iron(II) Bis( tert -butyl isocyanide)(5, 10, 15, 20-[4-(benzoyloxy)phenyl]porphyrin) coordination compound. J Organomet Chem 2017. [DOI: 10.1016/j.jorganchem.2017.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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5
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Govor EV, Al-Ameed K, Chakraborty I, Coste CS, Govor O, Sanakis Y, McGrady JE, Raptis RG. A Redox-Induced Spin-State Cascade in a Mixed-Valent Fe 3
(μ 3
-O) Triangle. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201610534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Evgen V. Govor
- Department of Chemistry and Biochemistry and the Biomedical Sciences Institute; Florida International University; 11200 SW 8th Street Miami FL 33199 USA
| | - Karrar Al-Ameed
- Department of Chemistry; University of Oxford; South Parks Road OX1 3QZ UK
- Faculty of Science; University of Kufa, Kufa St.; Najaf Iraq
| | | | - Carla S. Coste
- Department of Chemistry; University of Puerto Rico; San Juan PR 00934 USA
| | - Olena Govor
- Department of Chemistry and Biochemistry and the Biomedical Sciences Institute; Florida International University; 11200 SW 8th Street Miami FL 33199 USA
| | - Yiannis Sanakis
- Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, Ag. Paraskevi; 15310 Attiki Greece
| | - John E. McGrady
- Department of Chemistry; University of Oxford; South Parks Road OX1 3QZ UK
| | - Raphael G. Raptis
- Department of Chemistry and Biochemistry and the Biomedical Sciences Institute; Florida International University; 11200 SW 8th Street Miami FL 33199 USA
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6
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Govor EV, Al-Ameed K, Chakraborty I, Coste CS, Govor O, Sanakis Y, McGrady JE, Raptis RG. A Redox-Induced Spin-State Cascade in a Mixed-Valent Fe 3 (μ 3 -O) Triangle. Angew Chem Int Ed Engl 2017; 56:582-586. [PMID: 27918131 DOI: 10.1002/anie.201610534] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Indexed: 11/06/2022]
Abstract
One-electron reduction of a pyrazolate-bridged triangular Fe3 (μ3 -O) core induces a cascade wherein all three metal centers switch from high-spin Fe3+ to low-spin Fe2.66+ . This hypothesis is supported by spectroscopic data (1 H-NMR, UV-vis-NIR, infra-red, 57 Fe-Mössbauer, EPR), X-ray crystallographic characterization of the cluster in both oxidation states and also density functional theory. The reduction induces substantial contraction in all bond lengths around the metal centers, along with diagnostic shifts in the spectroscopic parameters. This is, to the best of our knowledge, the first example of a one-electron redox event causing concerted change in multiple iron centers.
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Affiliation(s)
- Evgen V Govor
- Department of Chemistry and Biochemistry and the Biomedical Sciences Institute, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA
| | - Karrar Al-Ameed
- Department of Chemistry, University of Oxford, South Parks Road, OX1 3QZ, UK.,Faculty of Science, University of Kufa, Kufa St., Najaf, Iraq
| | | | - Carla S Coste
- Department of Chemistry, University of Puerto Rico, San Juan, PR, 00934, USA
| | - Olena Govor
- Department of Chemistry and Biochemistry and the Biomedical Sciences Institute, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA
| | - Yiannis Sanakis
- Institute of Nanoscience and Nanotechnology, NCSR "Demokritos", Ag. Paraskevi, 15310, Attiki, Greece
| | - John E McGrady
- Department of Chemistry, University of Oxford, South Parks Road, OX1 3QZ, UK
| | - Raphael G Raptis
- Department of Chemistry and Biochemistry and the Biomedical Sciences Institute, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA
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7
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Hu B, He M, Yao Z, Schulz CE, Li J. Unique Axial Imidazole Geometries of Fully Halogenated Iron(II) Porphyrin Complexes: Crystal Structures and Mössbauer Spectroscopic Studies. Inorg Chem 2016; 55:9632-9643. [DOI: 10.1021/acs.inorgchem.6b01364] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Bin Hu
- College
of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Yanqi Lake, Huairou District, Beijing 101408, China
| | - Mingrui He
- College
of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Yanqi Lake, Huairou District, Beijing 101408, China
| | - Zhen Yao
- College
of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Yanqi Lake, Huairou District, Beijing 101408, China
| | - Charles E. Schulz
- Department
of Physics, Knox College, Galesburg, Illinois 61401, United States
| | - Jianfeng Li
- College
of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences, Yanqi Lake, Huairou District, Beijing 101408, China
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8
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He B, Schulz CE, Li J. Synthesis and characterization of a modified "picket fence" porphyrin complex - stronger π bonding interactions between Fe(ii) and axial ligands. Dalton Trans 2015; 44:13651-61. [PMID: 26145452 DOI: 10.1039/c5dt00941c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new, modified "picket fence" porphyrin is synthesized and its bis(imidazole)-ligated iron(ii) derivative [Fe(MbenTpivPP)(1-MeIm)(2)] is investigated. X-ray structure determinations demonstrate that [Fe(MbenTpivPP)(1-MeIm)(2)] has structural features of a near planar porphyrin plane, a relative perpendicular ligand orientation, and one unusually large absolute ligand orientation (φ). The combination of these features leads to a new type of species that is different from previously reported analogues. Further structural examination reveals a strong correlation between the mutual ligand orientations (θ) and the axial Fe-N(Im) bond distances, which is detailed for the first time. Mössbauer spectroscopic characterization shows that the low spin derivative has a quadrupole splitting of 0.99 mm s(-1) at 100 K.
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Affiliation(s)
- Baiyin He
- College of Materials Science and Opto-electronic Technology, University of Chinese Academy of Sciences, YanQi Lake, HuaiRou District, Beijing, 101408, China.
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9
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SANDERS LORIK, ARNOLD WILLIAMD, OLDFIELD ERIC. NMR, IR, Mössbauer and quantum chemical investigations of metalloporphyrins and metalloproteins. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1002/jpp.319] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We review contributions made towards the elucidation of CO and O2binding geometries in respiratory proteins. Nuclear magnetic resonance, infrared spectroscopy, Mössbauer spectroscopy, X-ray crystallography and quantum chemistry have all been used to investigate the Fe –ligand interactions. Early experimental results showed linear correlations between17O chemical shifts and the infrared stretching frequency (νCO) of the CO ligand in carbonmonoxyheme proteins and between the17O chemical shift and the13CO shift. These correlations led to early theoretical investigations of the vibrational frequency of carbon monoxide and of the13C and17O NMR chemical shifts in the presence of uniform and non-uniform electric fields. Early success in modeling these spectroscopic observables then led to the use of computational methods, in conjunction with experiment, to evaluate ligand-binding geometries in heme proteins. Density functional theory results are described which predict57Fe chemical shifts and Mössbauer electric field gradient tensors,17O NMR isotropic chemical shifts, chemical shift tensors and nuclear quadrupole coupling constants (e2qQ/h) as well as13C isotropic chemical shifts and chemical shift tensors in organometallic clusters, heme model metalloporphyrins and in metalloproteins. A principal result is that CO in most heme proteins has an essentially linear and untilted geometry (τ = 4 °, β = 7 °) which is in extremely good agreement with a recently published X-ray synchrotron structure. CO / O2discrimination is thus attributable to polar interactions with the distal histidine residue, rather than major Fe–C–O geometric distortions.
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Affiliation(s)
- LORI K. SANDERS
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA
| | - WILLIAM D. ARNOLD
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA
| | - ERIC OLDFIELD
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, IL 61801, USA
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10
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Du J, Perera R, Dawson JH. Alkylamine-ligated H93G myoglobin cavity mutant: a model system for endogenous lysine and terminal amine ligation in heme proteins such as nitrite reductase and cytochrome f. Inorg Chem 2011; 50:1242-9. [PMID: 21250678 DOI: 10.1021/ic101644u] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
His93Gly sperm whale myoglobin (H93G Mb) has the proximal histidine ligand removed to create a cavity for exogenous ligand binding, providing a remarkably versatile template for the preparation of model heme complexes. The investigation of model heme adducts is an important way to probe the relationship between coordination structure and catalytic function in heme enzymes. In this study, we have successfully generated and spectroscopically characterized the H93G Mb cavity mutant ligated with less common alkylamine ligands (models for Lys or the amine group of N-terminal amino acids) in numerous heme iron states. All complexes have been characterized by electronic absorption and magnetic circular dichroism spectroscopy in comparison with data for parallel imidazole-ligated H93G heme iron moieties. This is the first systematic spectral study of models for alkylamine- or terminal amine-ligated heme centers in proteins. High-spin mono- and low-spin bis-amine-ligated ferrous and ferric H93G Mb adducts have been prepared together with mixed-ligand ferric heme complexes with alkylamine trans to nitrite or imidazole as heme coordination models for cytochrome c nitrite reductase or cytochrome f, respectively. Six-coordinate ferrous H93G Mb derivatives with CO, NO, and O(2) trans to the alkylamine have also been successfully formed, the latter for the first time. Finally, a novel high-valent ferryl species has been generated. The data in this study represent the first thorough investigation of the spectroscopic properties of alkylamine-ligated heme iron systems as models for naturally occurring heme proteins ligated by Lys or terminal amines.
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Affiliation(s)
- Jing Du
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 20208, United States
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11
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Li J, Nair SM, Noll BC, Schulz CE, Scheidt WR. Relative axial ligand orientation in bis(imidazole)iron(II) porphyrinates: are "picket fence" derivatives different? Inorg Chem 2008; 47:3841-50. [PMID: 18351735 DOI: 10.1021/ic702498c] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis of three new bis(imidazole)-ligated iron(II) picket fence porphyrin derivatives, [Fe(TpivPP)(1-RIm) 2] 1-RIm = 1-methyl-, 1-ethyl-, or 1-vinylimidazole) are reported. X-ray structure determinations reveal that the steric requirements of the four alpha,alpha,alpha,alpha-o-pivalamidophenyl groups lead to very restricted rotation of the imidazole ligand on the picket side of the porphyrin plane; the crowding leads to an imidazole plane orientation eclipsing an iron-porphyrin nitrogen bond. An unusual feature for these diamagnetic iron(II) species is that all three derivatives have the two axial ligands with a relative perpendicular orientation; the dihedral angles between the two imidazole planes are 77.2 degrees , 62.4 degrees , and 78.5 degrees . All three derivatives have nearly planar porphyrin cores. Mössbauer spectroscopic characterization shows that all three derivatives have quadrupole splitting constants around 1.00 mm/s at 100K.
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Affiliation(s)
- Jianfeng Li
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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12
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Nasri H, Ellison MK, Shaevitz B, Gupta GP, Scheidt WR. Electronic, magnetic, and structural characterization of the five-coordinate, high-spin iron(II) nitrato complex [Fe(TpivPP)(NO3)]-. Inorg Chem 2006; 45:5284-90. [PMID: 16813390 PMCID: PMC1501086 DOI: 10.1021/ic052059i] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The preparation and characterization of the five-coordinate iron(II) porphyrinate derivative [Fe(TpivPP)(NO3)]- (TpivPP = picket-fence porphyrin) is described. Structural and magnetic susceptibility data support a high-spin state (S = 2) assignment for this species. The anionic axial nitrate ligand is O-bound, through a single O atom, with an Fe-O bond length of 2.069(4) A. The planar nitrate ligand bisects a N(p)-Fe-N(p) angle. The average Fe-N(p) bond length is 2.070(16) A. The Fe atom is located 0.49 A out of the 24-atom mean porphyrin plane toward the nitrate ligand. From solid-state Mössbauer data, the isomer shift of 0.98 mm/s at 77 K is entirely consistent with high-spin iron(II). However the quadrupole splitting of 3.59 mm/s at 77 K is unusually high for iron(II), S = 2 systems but within the range of other five-coordinate high-spin ferrous complexes with a single anionic axial ligand. Crystal data for [K(222)][Fe(TpivPP)(NO3)] x C6H5Cl: a = 17.888 (5) A, b = 21.500 (10) A, c = 22.514 (11) A, beta = 100.32 (3) degrees, monoclinic, space group P2(1)/n, V = 8519 A3, Z = 4.
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Affiliation(s)
- Habib Nasri
- Laboratoire de Physico-Chimie des Matériaux, Faculté des Sciences de Monastir, Avenue de l'environnement, 5019 Monastir, Tunisia
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13
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Teschner T, Yatsunyk L, Schünemann V, Paulsen H, Winkler H, Hu C, Scheidt WR, Walker FA, Trautwein AX. Models of the membrane-bound cytochromes: mössbauer spectra of crystalline low-spin ferriheme complexes having axial ligand plane dihedral angles ranging from 0 degree to 90 degrees. J Am Chem Soc 2006; 128:1379-89. [PMID: 16433558 PMCID: PMC1525297 DOI: 10.1021/ja056343k] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Crystalline samples of four low-spin Fe(III) octaalkyltetraphenylporphyrinate and two low-spin Fe(III) tetramesitylporphyrinate complexes, all of which are models of the bis-histidine-coordinated cytochromes of mitochondrial complexes II, III, and IV and chloroplast complex b(6)f, and whose molecular structures and EPR spectra have been reported previously, have been investigated in detail by Mössbauer spectroscopy. The six complexes and the dihedral angles between axial ligand planes of each are [(TMP)Fe(1-MeIm)(2)]ClO(4) (0 degree), paral-[(OMTPP)Fe(1-MeIm)(2)]Cl (19.5 degrees), paral-[(TMP)Fe(5-MeHIm)(2)]ClO(4) (26 degrees, 30 degrees for two molecules in the unit cell whose EPR spectra overlap), [(OETPP)Fe(4-Me(2)NPy)(2)]Cl (70 degrees), perp-[(OETPP)Fe(1-MeIm)(2)]Cl (73 degrees), and perp-[(OMTPP)Fe(1-MeIm)(2)]Cl (90 degrees). Of these, the first three have been shown to exhibit normal rhombic EPR spectra, each with three clearly resolved g-values, while the last three have been shown to exhibit "large g(max)" EPR spectra at 4.2 K. It is found that the hyperfine coupling constants of the complexes are consistent with those reported previously for low-spin ferriheme systems, with the largest-magnitude hyperfine coupling constant, A(zz), being considerably smaller for the "parallel" complexes (400-540 kG) than for the strictly perpendicular complex (902 kG), A(xx) being negative for all six complexes, and A(zz) and A(xx) being of similar magnitude for the "parallel" complexes (for example, for [(TMP)Fe(1-MeIm)(2)]Cl, A(zz) = 400 kG, A(xx) = -400 kG). In all cases, A(yy) is small but difficult to estimate with accuracy. With results for six structurally characterized model systems, we find for the first time qualitative correlations of g(zz), A(zz), and DeltaE(Q) with axial ligand plane dihedral angle Deltavarphi.
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14
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Han WG, Liu T, Lovell T, Noodleman L. DFT calculations of57Fe Mössbauer isomer shifts and quadrupole splittings for iron complexes in polar dielectric media: Applications to methane monooxygenase and ribonucleotide reductase. J Comput Chem 2006; 27:1292-306. [PMID: 16786546 DOI: 10.1002/jcc.20402] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
To predict the isomer shifts of Fe complexes in different oxidation and spin states more accurately, we have performed linear regression between the measured isomer shifts (delta(exp)) and DFT (PW91 potential with all-electron triple-zeta plus polarization basis sets) calculated electron densities at Fe nuclei [rho(0)] for the Fe(2+,2.5+) and Fe(2.5+,3+,3.5+,4+) complexes separately. The geometries and electronic structures of all complexes in the training sets are optimized within the conductor like screening (COSMO) solvation model. Based on the linear correlation equation delta(exp) = alpha[rho(0) - 11884.0] + C, the best fitting for 17 Fe(2+,2.5+) complexes (totally 31 Fe sites) yields alpha = -0.405 +/- 0.042 and C = 0.735 +/- 0.047 mm s(-1). The correlation coefficient is r = -0.876 with a standard deviation of SD = 0.075 mm s(-1). In contrast, the linear fitting for 19 Fe(2.5+,3+,3.5+,4+) complexes (totally 30 Fe sites) yields alpha = -0.393 +/- 0.030 and C = 0.435 +/- 0.014 mm s(-1), with the correlation coefficient r = -0.929 and a standard deviation SD = 0.077 mm s(-1). We provide a physical rationale for separating the Fe(2+,2.5+) fit from the Fe(2.5+,3+,3.5+,4+) fit, which also is clearly justified on a statistical empirical basis. Quadrupole splittings have also been calculated for these systems. The correlation between the calculated (DeltaE(Q(cal))) and experimental (DeltaE(Q(exp))) quadrupole splittings based on |DeltaE(Q(exp))| = A |DeltaE(Q(cal))| + B yields slope A, which is almost the ideal value 1.0 (A = 1.002 +/- 0.030) and intercept B almost zero (B = 0.033 +/- 0.068 mm s(-1)). Further calculations on the reduced diferrous and oxidized diferric active sites of class-I ribonucleotide reductase (RNR) and the hydroxylase component of methane monooxygenase (MMOH), and on a mixed-valent [(tpb)Fe3+(mu-O)(mu-CH3CO2)Fe4+(Me3[9]aneN3)]2+ (S = 3/2) complex and its corresponding diferric state have been performed. Calculated results are in very good agreement with the experimental data.
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Affiliation(s)
- Wen-Ge Han
- Department of Molecular Biology, TPC15, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, USA
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15
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Hu C, Noll BC, Schulz CE, Scheidt WR. Ligand orientation control in low-spin six-coordinate (porphinato)iron(II) species. Inorg Chem 2005; 44:4346-58. [PMID: 15934765 PMCID: PMC1502394 DOI: 10.1021/ic050320p] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The synthesis of a low-spin six-coordinate iron(II) porphyrinate in which the two axial ligands are forced to have a relative perpendicular orientation has been successfully accomplished for the first time. The reaction of four-coordinate (tetramesitylporphinato)iron(II) with 2-methylimidazole leads to the preparation of [Fe(TMP)(2-MeHIm)(2)] which cocrystallizes with five-coordinate [Fe(TMP)(2-MeHIm)]. The six-coordinate complex accommodates the sterically crowded pair of imidazoles with a strongly ruffled core and relative perpendicular orientation. This leads to shortened equatorial bonds of 1.963(6) A and slightly elongated axial Fe-N bond lengths of 2.034(9) A that are about 0.04 A shorter and 0.03 A longer, respectively, in comparison to those of the bis-imidazole-ligated iron(II) species with parallel oriented axial ligands. The Mossbauer spectrum shows a pair of quadrupole doublets that can be assigned to the components of the cocrystallized crystalline solid. High-spin five-coordinate [Fe(TMP)(2-MeHIm)] has DeltaE(Q) = 2.25 mm/s and delta = 0.90 mm/s at 15 K. The quadrupole splitting, DeltaE(Q), for [Fe(TMP)(2-MeHIm)(2)] is 1.71 mm/s, and the isomer shift is 0.43 mm/s at 15 K. The quadrupole splitting value is significantly larger than that found for low-spin iron(II) derivatives with relative parallel orientations for the two axial ligands. Mossbauer spectra thus provide a probe for ligand orientation when structural data are otherwise not available.
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Affiliation(s)
- Chuanjiang Hu
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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Nasri H, Ellison MK, Shang M, Schulz CE, Scheidt WR. Variable pi-bonding in iron(II) porphyrinates with nitrite, CO, and tert-butyl isocyanide: characterization of [Fe(TpivPP)(NO2)(CO)]-. Inorg Chem 2004; 43:2932-42. [PMID: 15106981 PMCID: PMC1764913 DOI: 10.1021/ic035119y] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The addition of the strongly pi-bonding ligands CO or tert-butyl isocyanide to the low-spin five-coordinate iron(II) nitrite species [Fe(TpivPP)(NO2)]- (TpivPP = picket fence porphyrin) gives two new six-coordinate species [Fe(TpivPP)(NO2)(CO)]- and [Fe(TpivPP)(NO2)(t-BuNC)]-. These species have been characterized by single-crystal structure determinations and by UV-vis, IR, and Mössbauer spectroscopies. All evidence shows that in the mixed-ligand iron(II) porphyrin species, [Fe(TpivPP)(NO2)(CO)]-, the two trans, pi-accepting ligands CO and nitrite compete for pi density. The CO ligand however dominates the bonding. The Fe-N(NO2) bond lengths for the two independent anions in the unit cell at 2.006(4) and 2.009(4) A are lengthened compared to other nitrite species with either no trans ligands or non-pi-accepting trans ligands to nitrite. The Fe-C(CO) bond lengths are 1.782(4) A and 1.789(5) A for the two anions. The two Fe-C-O angles at 175.5(4) and 177.5(4) degrees are essentially linear in both anions. The quadrupole splitting for [Fe(TpivPP)(NO2)(CO)]- was determined to be 0.32 mm/s, and the isomer shift was 0.18 mm/s at room temperature in zero applied field. Both of the Mössbauer parameters are much smaller than those found for six-coordinate low-spin iron(II) porphyrinates with neutral nitrogen-donating ligands as well as iron(II) nitro complexes. However, the Mössbauer parameters are typical of other six-coordinate CO porphyrinates signifying that CO is the more dominant ligand. The CO stretching frequency of 1974 cm(-1) is shifted only slightly to higher energy compared to six-coordinate CO complexes with neutral nitrogen-donor ligands trans to CO. Crystal data for [K(222)][Fe(TpivPP)(NO2)(CO)].1/2C6H5Cl: monoclinic, space group P2(1)/c, Z = 8, a = 33.548(6) A, b = 18.8172(15) A, c = 27.187(2) A, beta = 95.240(7) degrees, V = 17091(4) A3.
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Affiliation(s)
- Habib Nasri
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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Walker FA. Models of the Bis-Histidine-Ligated Electron-Transferring Cytochromes. Comparative Geometric and Electronic Structure of Low-Spin Ferro- and Ferrihemes. Chem Rev 2004; 104:589-615. [PMID: 14871136 DOI: 10.1021/cr020634j] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- F Ann Walker
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721-0041, USA.
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Yatsunyk LA, Carducci MD, Walker FA. Low-Spin Ferriheme Models of the Cytochromes: Correlation of Molecular Structure with EPR Spectral Type. J Am Chem Soc 2003; 125:15986-6005. [PMID: 14677991 DOI: 10.1021/ja036398r] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The preparation and characterization of the following bis-imidazole and bis-pyridine complexes of octamethyltetraphenylporphyrinatoiron(III), Fe(III)OMTPP, octaethyltetraphenylporphyrinatoiron(III), Fe(III)OETPP, and tetra-beta,beta'-tetramethylenetetraphenylporphyrinatoiron(III), Fe(III)TC(6)TPP, are reported: paral-[FeOMTPP(1-MeIm)(2)]Cl, perp-[FeOMTPP(1-MeIm)(2)]Cl, [FeOETPP(1-MeIm)(2)]Cl, [FeTC(6)TPP(1-MeIm)(2)]Cl, [FeOMTPP(4-Me(2)NPy)(2)]Cl, and [FeOMTPP(2-MeHIm)(2)]Cl. Crystal structure analysis shows that paral-[FeOMTPP(1-MeIm)(2)]Cl has its axial ligands in close to parallel orientation (the actual dihedral angle between the planes of the imidazole ligands is 19.5 degrees ), while perp-[FeOMTPP(1-MeIm)(2)]Cl has the axial imidazole ligand planes oriented at 90 degrees to each other and 29 degrees away from the closest N(P)-Fe-N(P) axis. [FeOETPP(1-MeIm)(2)]Cl has its axial ligands close to perpendicular orientation (the actual dihedral angle between the planes of the imidazole ligands is 73.1 degrees ). In all three cases the porphyrin core adopts relatively purely saddled geometry. The [FeTC(6)TPP(1-MeIm)(2)]Cl complex is the most planar and has the highest contribution of a ruffled component in the overall saddled structure compared to all other complexes in this study. The estimated numerical contribution of saddled and ruffled components is 0.68:0.32, respectively. Axial ligand planes are perpendicular to each other and 15.3 degrees away from the closest N(P)-Fe-N(P) axis. The Fe-N(P) bond is the longest in the series of octaalkyltetraphenylporphyrinatoiron(III) complexes due to [FeTC(6)TPP(1-MeIm)(2)]Cl having the least distorted porphyrin core. In addition to these three complexes, two crystalline forms each of [FeOMTPP(4-Me(2)NPy)(2)]Cl and [FeOMTPP(2-MeHIm)(2)]Cl were obtained. In all four of these cases the axial planes are in nearly perpendicular planes in spite of quite different geometries of the porphyrin cores (from purely saddled to saddled with 30% ruffling). The EPR spectral type correlates with the geometry of the OMTPP, OETPP and TC(6)TPP complexes. For the paral-[FeOMTPP(1-MeIm)(2)]Cl, a rhombic signal with g(1) = 1.54, g(2) = 2.51, and g(3) = 2.71 is consistent with nearly parallel axial ligand orientation. For all other complexes of this study, "large g(max)" signals are observed (g(max) = 3.61 - 3.27), as are observed for nearly perpendicular ligand plane arrangement. On the basis of this and previous work, the change from "large g(max)" to normal rhombic EPR signal occurs between axial ligand plane dihedral angles of 70 degrees and 30 degrees.
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Affiliation(s)
- Liliya A Yatsunyk
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721-0041, USA
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Neese F. Prediction and interpretation of the 57Fe isomer shift in Mössbauer spectra by density functional theory. Inorganica Chim Acta 2002. [DOI: 10.1016/s0020-1693(02)01031-9] [Citation(s) in RCA: 354] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Nemykin V, Kobayashi N, Chernii V, Belsky V. Mössbauer, Crystallographic, and Density Functional Theoretical Investigation of the Electronic Structure of Bis-Ligated Low-Spin Iron(II) Phthalocyanines. Eur J Inorg Chem 2001. [DOI: 10.1002/1099-0682(200103)2001:3<733::aid-ejic733>3.0.co;2-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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21
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Xu XP, Au-Yeung SCF. A DFT and 59Co Solid-State NMR Study of the Chemical Shielding Property and Electronic Interaction in the Metalloporphyrin System. J Am Chem Soc 2000. [DOI: 10.1021/ja9911723] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xiao-Ping Xu
- Contribution from the Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
| | - Steve C. F. Au-Yeung
- Contribution from the Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
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22
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Schünemann V, Benda R, Trautwein AX, Walker FA. Mössbauer spectroscopic studies of the six-coordinate heme-nitric oxide complex of iron(III) octaethylporphyrinN-methylimidazole, the first model of the nitrophorin-no complexes. Isr J Chem 2000. [DOI: 10.1002/ijch.5680400103] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Munro OQ, Madlala PS, Warby RAF, Seda TB, Hearne G. Structural, Conformational, and Spectroscopic Studies of Primary Amine Complexes of Iron(II) Porphyrins. Inorg Chem 1999; 38:4724-4736. [PMID: 11671197 DOI: 10.1021/ic990178q] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Three novel bis(primary amine)iron(II) porphyrins [Fe(TPP)(RNH(2))(2)], where RNH(2) = 1-butylamine, benzylamine, and phenethylamine, have been synthesized and characterized by X-ray crystallography and IR, electronic, and Mössbauer spectroscopy. The compounds provide unprecedented structural data for the coordination of primary amines by iron(II) porphyrins. The Fe-N(ax) distances of [Fe(TPP)(1-BuNH(2))(2)], [Fe(TPP)(BzNH(2))(2)], and [Fe(TPP)(PhCH(2)CH(2)NH(2))(2)] are 2.039(3), 2.043(3), and 2.028(2) Å, respectively. The Fe-N(p) distances of the three complexes average 1.990(2) Å. The zero-field Mössbauer spectra (5-300 K) show comparable isomer shifts (0.393(1)-0.493(1) mm/s) and quadrupole splittings (1.144(6)-1.204(3) mm/s) that are consistent with an S = 0 iron(II) assignment in each case. The bis(primary amine) complexes are structurally and spectroscopically similar to [Fe(TPP)(Py)(2)] derivatives, where Py = an unsubstituted pyridine. Molecular mechanics (MM) calculations with a force field parametrized for primary and secondary amine complexes of iron(II) porphyrins show that stable conformations arise when the alpha-CH(2) and NH(2) protons of the coordinated ligands are staggered relative to the Fe-N(p) bonds of the porphyrin core. The lowest energy conformations of the three [Fe(TPP)(RNH(2))(2)] complexes therefore have the ligand alpha-carbons positioned directly over the Fe-N(p) bonds of the porphyrin core. The X-ray structure of [Fe(TPP)(PhCH(2)CH(2)NH(2))(2)] lies close to the global minimum (phi(1), phi(2) = 0, 180 degrees ) on the potential surface, while [Fe(TPP)(BzNH(2))(2)] and [Fe(TPP)(1-BuNH(2))(2)] show deviations that may be attributed to packing interactions in the solid and intrinsically low barriers to axial ligand rotation (<0.5 kcal/mol). Three types of minimum energy conformation are accessible for [Fe(TPP)(Pip)(2)]. The lowest energy conformation has an S(4)-ruffled porphyrin core. The conformation which matches the X-ray structure (Radonovich, L. J.; Bloom, A.; Hoard, J. L. J. Am. Chem. Soc. 1972, 94, 2073-2078) is a local minimum (1.6 kcal/mol higher in energy than the global minimum) with exact inversion symmetry. Higher in vacuo strain energy barriers ( approximately 2.2 kcal/mol) separate the potential minima of [Fe(TPP)(Pip)(2)], consistent with the increased bulk of the secondary amine axial ligands.
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Affiliation(s)
- Orde Q. Munro
- School of Chemical and Physical Sciences, University of Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa, and Department of Physics, University of the Witwatersrand, P.O. Wits 2050, Johannesburg, South Africa
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Kalodimos CG, Gerothanassis IP, Rose E, Hawkes GE, Pierattelli R. Iron-57 Nuclear Shieldings as a Quantitative Tool for Estimating Porphyrin Ruffling in Hexacoordinated Carbonmonoxy Heme Model Compounds in Solution. J Am Chem Soc 1999. [DOI: 10.1021/ja983889g] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Charalampos G. Kalodimos
- Contribution from the Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, Ioannina GR-45110, Greece, Laboratoire de Synthèse Organique et Organométallique, Université P. et M. Curie, UMR CNRS 7611, 4 Place Jussieu, 75252 Paris Cedex 05, France, Department of Chemistry, Queen Mary and Westfield College, University of London, Mile End Road, London E1 4NS, U.K., and Department of Chemistry, University of Florence, Via G. Capponi 7, 50121 Florence, Italy
| | - Ioannis P. Gerothanassis
- Contribution from the Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, Ioannina GR-45110, Greece, Laboratoire de Synthèse Organique et Organométallique, Université P. et M. Curie, UMR CNRS 7611, 4 Place Jussieu, 75252 Paris Cedex 05, France, Department of Chemistry, Queen Mary and Westfield College, University of London, Mile End Road, London E1 4NS, U.K., and Department of Chemistry, University of Florence, Via G. Capponi 7, 50121 Florence, Italy
| | - Eric Rose
- Contribution from the Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, Ioannina GR-45110, Greece, Laboratoire de Synthèse Organique et Organométallique, Université P. et M. Curie, UMR CNRS 7611, 4 Place Jussieu, 75252 Paris Cedex 05, France, Department of Chemistry, Queen Mary and Westfield College, University of London, Mile End Road, London E1 4NS, U.K., and Department of Chemistry, University of Florence, Via G. Capponi 7, 50121 Florence, Italy
| | - Geoffrey E. Hawkes
- Contribution from the Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, Ioannina GR-45110, Greece, Laboratoire de Synthèse Organique et Organométallique, Université P. et M. Curie, UMR CNRS 7611, 4 Place Jussieu, 75252 Paris Cedex 05, France, Department of Chemistry, Queen Mary and Westfield College, University of London, Mile End Road, London E1 4NS, U.K., and Department of Chemistry, University of Florence, Via G. Capponi 7, 50121 Florence, Italy
| | - Roberta Pierattelli
- Contribution from the Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, Ioannina GR-45110, Greece, Laboratoire de Synthèse Organique et Organométallique, Université P. et M. Curie, UMR CNRS 7611, 4 Place Jussieu, 75252 Paris Cedex 05, France, Department of Chemistry, Queen Mary and Westfield College, University of London, Mile End Road, London E1 4NS, U.K., and Department of Chemistry, University of Florence, Via G. Capponi 7, 50121 Florence, Italy
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25
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Godbout N, Havlin R, Salzmann R, Debrunner PG, Oldfield E. Iron-57 NMR Chemical Shifts and Mössbauer Quadrupole Splittings in Metalloporphyrins, Ferrocytochrome c, and Myoglobins: A Density Functional Theory Investigation. J Phys Chem A 1998. [DOI: 10.1021/jp972542h] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nathalie Godbout
- Department of Chemistry, University of Illinois at UrbanaChampaign, 600 South Mathews Avenue, Urbana, Illinois 61801, and Department of Physics, University of Illinois at UrbanaChampaign, 1110 West Green Street, Urbana, Illinois 61801
| | - Robert Havlin
- Department of Chemistry, University of Illinois at UrbanaChampaign, 600 South Mathews Avenue, Urbana, Illinois 61801, and Department of Physics, University of Illinois at UrbanaChampaign, 1110 West Green Street, Urbana, Illinois 61801
| | - Renzo Salzmann
- Department of Chemistry, University of Illinois at UrbanaChampaign, 600 South Mathews Avenue, Urbana, Illinois 61801, and Department of Physics, University of Illinois at UrbanaChampaign, 1110 West Green Street, Urbana, Illinois 61801
| | - Peter G. Debrunner
- Department of Chemistry, University of Illinois at UrbanaChampaign, 600 South Mathews Avenue, Urbana, Illinois 61801, and Department of Physics, University of Illinois at UrbanaChampaign, 1110 West Green Street, Urbana, Illinois 61801
| | - Eric Oldfield
- Department of Chemistry, University of Illinois at UrbanaChampaign, 600 South Mathews Avenue, Urbana, Illinois 61801, and Department of Physics, University of Illinois at UrbanaChampaign, 1110 West Green Street, Urbana, Illinois 61801
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26
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Safo MK, Nesset MJM, Walker FA, Debrunner PG, Scheidt WR. Models of the Cytochromes. Axial Ligand Orientation and Complex Stability in Iron(II) Porphyrinates: The Case of the Noninteracting dπ Orbitals. J Am Chem Soc 1997. [DOI: 10.1021/ja9715657] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Martin K. Safo
- Contribution from the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Department of Chemistry, University of Arizona, Tucson, Arizona 85721, and Department of Physics, University of Illinois, Urbana, Illinois 61801
| | - Marlys J. M. Nesset
- Contribution from the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Department of Chemistry, University of Arizona, Tucson, Arizona 85721, and Department of Physics, University of Illinois, Urbana, Illinois 61801
| | - F. Ann Walker
- Contribution from the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Department of Chemistry, University of Arizona, Tucson, Arizona 85721, and Department of Physics, University of Illinois, Urbana, Illinois 61801
| | - Peter G. Debrunner
- Contribution from the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Department of Chemistry, University of Arizona, Tucson, Arizona 85721, and Department of Physics, University of Illinois, Urbana, Illinois 61801
| | - W. Robert Scheidt
- Contribution from the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Department of Chemistry, University of Arizona, Tucson, Arizona 85721, and Department of Physics, University of Illinois, Urbana, Illinois 61801
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Grodzicki M, Flint H, Winkler H, Walker FA, Trautwein AX. Electronic Structure, Porphyrin Core Distortion, and Fluxional Behavior of Bis-Ligated Low-Spin Iron(II) Porphyrinates. J Phys Chem A 1997. [DOI: 10.1021/jp963039s] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael Grodzicki
- Institut für Physik, Medizinische Universität zu Lübeck, 160 Ratzeburger Allee, 23538 Lübeck, Germany, and Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - Holger Flint
- Institut für Physik, Medizinische Universität zu Lübeck, 160 Ratzeburger Allee, 23538 Lübeck, Germany, and Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - Heiner Winkler
- Institut für Physik, Medizinische Universität zu Lübeck, 160 Ratzeburger Allee, 23538 Lübeck, Germany, and Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - F. Ann Walker
- Institut für Physik, Medizinische Universität zu Lübeck, 160 Ratzeburger Allee, 23538 Lübeck, Germany, and Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - Alfred X. Trautwein
- Institut für Physik, Medizinische Universität zu Lübeck, 160 Ratzeburger Allee, 23538 Lübeck, Germany, and Department of Chemistry, University of Arizona, Tucson, Arizona 85721
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Nesset MJM, Shokhirev NV, Enemark PD, Jacobson SE, Walker FA. Models of the Cytochromes. Redox Properties and Thermodynamic Stabilities of Complexes of “Hindered” Iron(III) and Iron(II) Tetraphenylporphyrinates with Substituted Pyridines and Imidazoles. Inorg Chem 1996. [DOI: 10.1021/ic960491h] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - Paul D. Enemark
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | | | - F. Ann Walker
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
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