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Schrage BR, Zhou W, Harrison LA, Nevonen DE, Thompson JR, Prosser KE, Walsby CJ, Ziegler CJ, Leznoff DB, Nemykin VN. Resolving a Half-Century-Long Controversy between (Magneto)optical and EPR Spectra of Single-Electron-Reduced [PcFe] −, [PcFeL] −, and [PcFeX] 2– Complexes: Story of a Double Flip. Inorg Chem 2022; 61:20177-20199. [DOI: 10.1021/acs.inorgchem.2c03456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Briana R. Schrage
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Wen Zhou
- Department of Chemistry, Simon Fraser University, Burnaby, British ColumbiaV5A 1S6, Canada
| | - Laurel A. Harrison
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee37996, United States
| | - Dustin E. Nevonen
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee37996, United States
| | - John R. Thompson
- Department of Chemistry, Simon Fraser University, Burnaby, British ColumbiaV5A 1S6, Canada
| | - Kathleen E. Prosser
- Department of Chemistry, Simon Fraser University, Burnaby, British ColumbiaV5A 1S6, Canada
| | - Charles J. Walsby
- Department of Chemistry, Simon Fraser University, Burnaby, British ColumbiaV5A 1S6, Canada
| | | | - Daniel B. Leznoff
- Department of Chemistry, Simon Fraser University, Burnaby, British ColumbiaV5A 1S6, Canada
| | - Victor N. Nemykin
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee37996, United States
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2
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Scheidt WR, Cheng B, Venugopal Reddy K, Brancato KE. Alternant Bond Distances in Octaethylporphyrin π-Cation Radicals. J PORPHYR PHTHALOCYA 2017. [DOI: 10.1142/s1088424617500080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The possible appearance and nature of alternant bond distance patterns in the inner 16-membered ring of several octaethylporphyrin [Formula: see text]-cation radicals has been investigated. This study was made possible by recognizing an unexpected solvent system, namely dichloromethane/chloroform, even though the [Formula: see text]-cation species have extremely limited solubility in chloroform. A total of six [M(OEP[Formula: see text]][Formula: see text] derivatives were studied by single-crystal X-ray structure determinations. Two new zinc derivatives display, quantitatively, the same alternant pattern observed previously. A new nickel complex shows a smaller but now probably significant alternant pattern. However, a copper derivative, independently analyzed twice, shows no evidence for an alternant pattern. The importance of ring–ring interactions on the energy of the top two orbitals is shown by two distinct magnesium derivatives. The derivative with strongly overlapped rings displays an alternant bond distance pattern, whereas the other, with a modestly overlapped ring pair, does not. This suggests the importance of strong ring–ring interactions in leading to a pseudo-Jahn-Teller state; this hypothesis is also supported by other prior results.
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Affiliation(s)
- W. Robert Scheidt
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Beisong Cheng
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - K. Venugopal Reddy
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Kristin E. Brancato
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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3
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Liu Q, Guo C. Theoretical studies and industrial applications of oxidative activation of inert C-H bond by metalloporphyrin-based biomimetic catalysis. Sci China Chem 2012. [DOI: 10.1007/s11426-012-4739-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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TERNER JAMES, GOLD AVRAM, WEISS RAYMOND, MANDON DOMINIQUE, TRAUTWEIN ALFREDX. Symmetry states of metalloporphyrin π-cation radicals, models for peroxidase compound I. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1002/jpp.315] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Oxoferryl porphyrin π-cation radical active sites of compound I intermediates which are found in enzymes such as peroxidases and catalases have been extensively modeled by oxidized synthetic metalloporphyrins. The electronic symmetry states of these compounds were initially assigned on the basis of electronic absorption data. In recent years new experimental and theoretical results have become available which have led to a re-evaluation and modification of the original assignments. A historical perspective of these developments is provided in the context of recent NMR, resonance Raman, and other spectroscopic data and theoretical calculations for the synthetic models and enzymatic systems.
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Affiliation(s)
- JAMES TERNER
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284-2006, USA
| | - AVRAM GOLD
- Department of Environmental Sciences and Engineering, The University of North Carolina at Chapel Hill, NC 27599-7400, USA
| | - RAYMOND WEISS
- Laboratoire de Cristallochimie et de Chimie Structurale (UMR 7513), Institut Le Bel, Université Louis Pasteur, 67070 Strasbourg, France
| | - DOMINIQUE MANDON
- Laboratoire de Cristallochimie et de Chimie Structurale (UMR 7513), Institut Le Bel, Université Louis Pasteur, 67070 Strasbourg, France
| | - ALFRED X. TRAUTWEIN
- Institut für Physik, Medizinische Universität zu Lübeck, D-23538 Lübeck, Germany
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YANG SUNGIK, SETH JYOTI, STRACHAN JONPAUL, GENTEMANN STEVE, KIM DONGHO, HOLTEN DEWEY, LINDSEY JONATHANS, BOCIAN DAVIDF. Ground and Excited State Electronic Properties of Halogenated Tetraarylporphyrins: Tuning the Building Blocks for Porphyrin-based Photonic Devices. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1002/(sici)1099-1409(199902)3:2<117::aid-jpp110>3.0.co;2-x] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The rational design of molecular photonic devices relies on the ability to select components with predictable electronic structure, excited state lifetimes and redox chemistry. Electronic communication in multiporphyrin arrays depends critically on the relative energies and electron density distributions of the frontier molecular orbitals, especially the energetically close highest occupied molecular orbitals (a2u and a1u). To explore how these ground and excited state properties can be modulated, we have synthesized and characterized 40 free base ( Fb ), magnesium and zinc tetraarylporphyrins. The porphyrins bear meso-substituents with the following substitution patterns: (1) four identical substituents (phenyl, o-chlorophenyl, p-chlorophenyl, o,o'-difluorophenyl, pentafluorophenyl, mesityl); (2) one, two, three or four o,o'-dichlorophenyl substituents; (3) one p-ethynylphenyl group and three mesityl or pentafluorophenyl groups; (4) one p-ethynyl-o,o″-dichlorophenyl or p-ethynyl-o,o″-dimethylphenyl and three phenyl groups. For each neutral complex the ground state electronic properties were investigated using electrochemical methods and optical absorption spectroscopy. Similarly the absorption, emission, and relaxation properties of the lowest singlet excited state were probed by time-resolved absorption and fluorescence methods. Each oxidized complex was investigated by static absorption and liquid and frozen solution EPR spectroscopy. The collective results of these investigations have provided insights into the direct (orbital overlap) and indirect (inductive/conjugative) mechanisms by which halogenated phenyl rings influence the static and dynamic electronic properties of neutral and oxidized porphyrinic chromophores. Three key findings are as follows. (1) The effective electron-withdrawing strength of halogenated phenyl rings required to reverse the ordering of the a2u and a1u HOMOs in Mg versus Zn tetraarylporphyrins has been elucidated. (2) Appropriate halogenation can significantly increase the excited state lifetime of a Zn porphyrin relative to the unsubstituted complex. (3) Halogenation can be used to modulate redox potentials in a manner that complements the enhancement of other electronic properties. The insights gained from study of this library of porphyrins provide a foundation for tuning the electronic properties of monomeric porphyrins as building blocks for multichromophoric assemblies in optoelectronics and other applications.
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Affiliation(s)
- SUNG IK YANG
- Department of Chemistry, Washington University, St Louis, MO 63130-4889, USA
| | - JYOTI SETH
- Department of Chemistry, University of California, Riverside, CA 92521-0403, USA
| | - JON-PAUL STRACHAN
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA
| | - STEVE GENTEMANN
- Department of Chemistry, Washington University, St Louis, MO 63130-4889, USA
| | - DONGHO KIM
- Department of Chemistry, Washington University, St Louis, MO 63130-4889, USA
| | - DEWEY HOLTEN
- Department of Chemistry, Washington University, St Louis, MO 63130-4889, USA
| | - JONATHAN S. LINDSEY
- Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA
| | - DAVID F. BOCIAN
- Department of Chemistry, University of California, Riverside, CA 92521-0403, USA
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6
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Abstract
The term ‘high-valent’ refers to iron complexes of porphyrins and related macrocycles in which the oxidation state of the iron center exceeds III. High-valent iron porphyrins and chlorins are important biological transients whose intermediacy has been demonstrated in numerous peroxidase and catalase enzymes. Two species, compounds I and II, are spectroscopically detectable upon stoichiometric addition of monooxygen donors to resting ferric enzymes. Compounds I and II are formally two and one oxidizing equivalents respectively above the ferric state. In compound II the oxidizing equivalent has been shown by spectroscopic studies to be located on iron as an oxoiron(IV) unit. The spectroscopic and magnetic properties of compound I support the structural assignment of an S = 1 oxoiron(IV) unit magnetically coupled to a heme π-cation radical (S = 1/2). Studies on model hemes have contributed much to the understanding of protein chemistry. Much work has been accomplished with meso-tetaarylporphyrins and, more recently, with physiologically congruent meso-unsubstituted pyrrole β-substituted complexes. Compounds I of both proteins and synthetic models have been characterized by a wide array of spectroscopic methods, including UV-vis, NMR, resonance Raman, EPR, variable-temperature/variable-field magnetic Mössbauer, magnetic circular dichroism and extended X-ray absorption fine structure spectroscopy. Results of these studies are summarized. Recent developments, which promise to yield a detailed picture of electronic structure, are variable-temperature magnetic circular dichroism, studies in the pre-K-edge region and L-edge X-ray absorption spectroscopy. Time-resolved X-ray diffraction techniques have been applied to obtain the first structural data on the protein forms of compound I.
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Affiliation(s)
- AVRAM GOLD
- Department of Environmental Sciences and Engineering, CB7400, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7400, USA
| | - RAYMOND WEISS
- Institut Le Bel, 4, rue Blaise Pascal, 67000 Strasbourg, France
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7
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Pan Z, Newcomb M. Acid-catalyzed disproportionation of oxoiron(IV) porphyrins to give oxoiron(IV) porphyrin radical cations. INORG CHEM COMMUN 2011; 14:968-970. [PMID: 21572532 DOI: 10.1016/j.inoche.2011.03.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Disproportionation of oxoiron(IV) porphyrin (Compound II) to oxoiron(IV) porphyrin radical cation (Compound I) was studied in three P450 model systems with different electronic structures. Direct conversion of Compound II to Compound I has been observed for 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin (TDCPP) in acid-catalyzed reactions in a mixed solvent of acetonitrile and water (1:1, v/v) containing excess m-CPBA oxidant, with a second-order rate constant of (1.3 ± 0.2) × 10(2) M(-1) s(-1). The acid-catalyzed disproportionation heavily depends on the electron demand of the substituted aryl groups on the porphyrin macrocycle. The disproportionation equilibrium constants show drastic change for the three porphyrin systems.
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Affiliation(s)
- Zhengzheng Pan
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607
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8
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Unprecedented Peroxidase-like Activity of Rhodnius prolixus Nitrophorin 2: Identification of the [FeIV═O Por•]+ and [FeIV═O Por](Tyr38•) Intermediates and Their Role(s) in Substrate Oxidation. Biochemistry 2010; 49:8857-72. [DOI: 10.1021/bi100499a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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9
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Ye S, Tuttle T, Bill E, Simkhovich L, Gross Z, Thiel W, Neese F. The Electronic Structure of Iron Corroles: A Combined Experimental and Quantum Chemical Study. Chemistry 2008; 14:10839-51. [DOI: 10.1002/chem.200801265] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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10
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Bryliakov KP, Talsi EP. Iron-Catalyzed Oxidation of Thioethers by Iodosylarenes: Stereoselectivity and Reaction Mechanism. Chemistry 2007; 13:8045-50. [PMID: 17611952 DOI: 10.1002/chem.200700566] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Catalytic properties of a series of iron(III)-salen (salen=N,N'-bis(salicylidene)ethylenediamine dianion) and related complexes in asymmetric sulfoxidation reactions, with iodosylarenes as terminal oxidants, have been explored. These catalysts have been found to efficiently catalyze oxidation of alkyl aryl sulfides to sulfoxides with high chemoselectivity (up to 100 %) and moderate-to-high enantioselectivity (up to 84 % with isopropylthiobenzene and iodosylmesitylene), the TON (TON=turnover number) approaching 500. The influence of the ligand (electronic and steric effects of the substituents), oxidant, and substrate structures on the oxidation stereoselectivity has been investigated systematically. The structure of the reactive intermediates (complexes of the type [Fe(III)(ArIO)(salen)] and the reaction mechanism have been revealed by both mechanistic studies with different iodosylarenes and direct in situ (1)H NMR observation of the formation of the reactive species and its reaction with the substrate.
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Affiliation(s)
- Konstantin P Bryliakov
- Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, 630090, Pr. Lavrentieva 5, Novosibirsk, Russia.
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11
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Groves JT. High-valent iron in chemical and biological oxidations. J Inorg Biochem 2006; 100:434-47. [PMID: 16516297 DOI: 10.1016/j.jinorgbio.2006.01.012] [Citation(s) in RCA: 452] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2006] [Accepted: 01/16/2006] [Indexed: 11/26/2022]
Abstract
Various aspects of the reactivity of iron(IV) in chemical and biological systems are reviewed. Accumulated evidence shows that the ferryl species [Fe(IV)O](2+) can be formed under a variety of conditions including those related to the ferrous ion-hydrogen peroxide system known as Fenton's reagent. Early evidence that such a species could hydroxylate typical aliphatic C-H bonds included regioselectivities and stereospecificities for cyclohexanol hydroxylation that could not be accounted for by a freely diffusing hydroxyl radical. Iron(IV) porphyrin complexes are also found in the catalytic cycles of cytochrome P450 and chloroperoxidase. Model oxo-iron(IV) porphyrin complexes have shown reactivity similar to the proposed enzymatic intermediates. Mechanistic studies using mechanistically diagnostic substrates have implicated a radical rebound scenario for aliphatic hydroxylation by cytochrome P450. Likewise, several non-heme diiron hydroxylases, AlkB (Omega-hydroxylase), sMMO (soluble methane monooxygenase), XylM (xylene monooxygenase) and T4moH (toluene monooxygenase) all show clear indications of radical rearranged products indicating that the oxygen rebound pathway is a ubiquitous mechanism for hydrocarbon oxygenation by both heme and non-heme iron enzymes.
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Affiliation(s)
- John T Groves
- Department of Chemistry, Princeton University, Washington Road, Princeton, NJ 08544, USA.
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12
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Terner J, Palaniappan V, Gold A, Weiss R, Fitzgerald MM, Sullivan AM, Hosten CM. Resonance Raman spectroscopy of oxoiron(IV) porphyrin π-cation radical and oxoiron(IV) hemes in peroxidase intermediates. J Inorg Biochem 2006; 100:480-501. [PMID: 16513173 DOI: 10.1016/j.jinorgbio.2006.01.008] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Accepted: 01/04/2006] [Indexed: 11/15/2022]
Abstract
The catalytic cycle intermediates of heme peroxidases, known as compounds I and II, have been of long standing interest as models for intermediates of heme proteins, such as the terminal oxidases and cytochrome P450 enzymes, and for non-heme iron enzymes as well. Reports of resonance Raman signals for compound I intermediates of the oxo-iron(IV) porphyrin pi-cation radical type have been sometimes contradictory due to complications arising from photolability, causing compound I signals to appear similar to those of compound II or other forms. However, studies of synthetic systems indicated that protein based compound I intermediates of the oxoiron(IV) porphyrin pi-cation radical type should exhibit vibrational signatures that are different from the non-radical forms. The compound I intermediates of horseradish peroxidase (HRP), and chloroperoxidase (CPO) from Caldariomyces fumago do in fact exhibit unique and characteristic vibrational spectra. The nature of the putative oxoiron(IV) bond in peroxidase intermediates has been under discussion in the recent literature, with suggestions that the Fe(IV)O unit might be better described as Fe(IV)-OH. The generally low Fe(IV)O stretching frequencies observed for proteins have been difficult to mimic in synthetic ferryl porphyrins via electron donation from trans axial ligands alone. Resonance Raman studies of iron-oxygen vibrations within protein species that are sensitive to pH, deuteration, and solvent oxygen exchange, indicate that hydrogen bonding to the oxoiron(IV) group within the protein environment contributes to substantial lowering of Fe(IV)O frequencies relative to those of synthetic model compounds.
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Affiliation(s)
- James Terner
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284-2006, USA.
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13
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Humphrey J, Kuciauskas D. Charge-Transfer States Determine Iron Porphyrin Film Third-Order Nonlinear Optical Properties in the near-IR Spectral Region. J Phys Chem B 2004. [DOI: 10.1021/jp0485643] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jonathan Humphrey
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, P.O. Box 842006, Richmond, Virginia 23284-2006
| | - Darius Kuciauskas
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main Street, P.O. Box 842006, Richmond, Virginia 23284-2006
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14
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Vangberg T, Lie R, Ghosh A. Symmetry-breaking phenomena in metalloporphyrin pi-cation radicals. J Am Chem Soc 2002; 124:8122-30. [PMID: 12095358 DOI: 10.1021/ja011438h] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Density functional theory (DFT) calculations of the energetics, molecular structures, and spin density profiles of metalloporphyrin pi-cation radicals suggest that the common practice of describing these radicals in terms of a universal A(1u)/A(2u) dichotomy is often not justified, confirming a possibility first foreseen by Prendergast and Spiro (ref 15) over a decade ago on the basis of vibrational spectroscopy and semiempirical calculations. Because of near-degeneracy of the a(1u) and a(2u) HOMOs of many metalloporphyrins, the cation radicals derived from these compounds undergo a pseudo-Jahn-Teller (pJT) distortion and are, therefore, best described as (2)A(u) with reference to the C(4h) point group, rather than as (2)A(1u) (D(4h) or (2)A(2u) (D(4h)). We find that the porphyrin cation radicals undergo a pJT distortion if the energy difference between the (2)A(1u) and (2)A(2u) pi-cation radicals, optimized under D(4h) symmetry constraints, is less than 0.15 eV. According to this criterion, metallo-porphine and metallo-OEP pi-cation radicals should always be pJT-distorted and metallo-meso-tetrahalogenoporphyrin radicals should not. For [Zn(TPP(*))](+), the (2)A(1u)/(2)A(2u) energy difference is almost exactly at the threshold of 0.15 eV, consistent with the experimental observation of both symmetry-broken and undistorted structures for this species. The (2)A(1u)/(2)A(2u) energy difference (when the molecular geometries are optimized under a D(4h) symmetry constraint) also appears to govern whether the real pJT-distorted cation radical is more A(1u)- or A(2u)-like in terms of its spin density profile. Because many metalloporphyrin pi-cation radicals exist as cofacial dimers in the crystalline phase, we examined the symmetries and structures of the model compounds [[Zn(P)](2)](+,2+) by means of DFT geometry optimizations. The results showed that dimerization has relatively little impact on the bond length alternation in the individual rings. A final interesting result, consistent with experiment, is that the bond length alternation in the delocalized mixed-valence dimer [[Zn(P)](2)](+) is about half that found for [[Zn(P)](2)](2+).
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Affiliation(s)
- Torgil Vangberg
- Department of Chemistry, Faculty of Science, University of Tromsø, N-9037 Tromsø, Norway
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15
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Nakamoto K. Resonance Raman spectra and biological significance of high-valent iron(IV,V) porphyrins. Coord Chem Rev 2002. [DOI: 10.1016/s0010-8545(01)00425-8] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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16
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Ikeue T, Ohgo Y, Saitoh T, Yamaguchi T, Nakamura M. Factors affecting the electronic ground state of low-spin iron(III) porphyrin complexes. Inorg Chem 2001; 40:3423-34. [PMID: 11421688 DOI: 10.1021/ic001412b] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To determine the factors affecting the ground-state electron configuration of low-spin Fe(III) porphyrin complexes, we have examined the (1)H NMR, (13)C NMR, and EPR spectra of a series of low-spin bis-ligated Fe(III) porphyrin complexes [Fe(Por)L(2)](+/-), in which the positions of porphyrin substituents and the coordination ability of axial ligands are different. The seven porphyrins used in this study are meso-tetraalkylporphyrins (TRP: R is propyl, cyclopropyl, or isopropyl), meso-tetraphenylporphyrin (TPP), meso-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin, and 5,10,15,20-tetraphenyl-2,3,7,8,12,13,17,18-octaalkylporphyrins (ORTPP: R is methyl or ethyl). The porphyrin cores of TRP are more or less S(4)-ruffled depending on the bulkiness of the alkyl substituents, while those of ORTPP are highly S(4)-saddled. Three types of axial ligands are examined which have the following characteristics in ligand field theory: they are (i) strong sigma-donating imidazole (HIm), (ii) strong sigma-donating and weak pi-accepting cyanide (CN(-)), and (iii) weak sigma-donating and strong pi-accepting tert-butyl isocyanide ((t)BuNC). In the case of the bis(HIm) complexes, only the isopropyl complex, [Fe(T(i)PrP)(HIm)(2)](+), has shown the less common (d(xz), d(yz))(4)(d(xy))(1) ground state; the other six complexes have exhibited the common (d(xy))(2)(d(xz), d(yz))(3) ground state. When the axial imidazole is replaced by cyanide, even the propyl and cyclopropyl complexes have shown the (d(xz), d(yz))(4)(d(xy))(1) ground state; the TPP and ORTPP complexes have still maintained the common (d(xy))(2)(d(xz), d(yz))(3) ground state. In the case of the bis((t)()BuNC) complexes, all the complexes have shown the (d(xz), d(yz))(4)(d(xy))(1) ground state. However, the contribution of the (d(xz), d(yz))(4)(d(xy))(1) state to the electronic ground state differs from complex to complex; the (d(xz), d(yz))(4)(d(xy))(1) contribution is the largest in [Fe(T(i)PrP)((t)()BuNC)(2)](+) and the smallest in [Fe(OETPPP)((t)BuNC)(2)](+). We have then examined the electronic ground state of low-spin [Fe(OEP)((t)BuNC)(2)](+) and [Fe(ProtoIXMe(2))((t)BuNC)(2)](+); OEP and ProtoIXMe(2) represent 2,3,7,8,12,13,17,18-octaethylporphyrin and protoporphyrin-IX dimethyl ester, respectively. These porphyrins have a(1u) HOMO in contrast to the other seven porphyrins that have a(2u) HOMO. The (13)C NMR and EPR studies have revealed that the contribution of the (d(xz), d(yz))(4)(d(xy))(1) state in these complexes is as small as that in [Fe(OETPP)((t)BuNC)(2)](+). On the basis of these results, we have concluded that the low-spin iron(III) porphyrins that have (i) strong axial ligands, (ii) highly saddle shaped porphyrin rings, (iii) porphyrins with a(1u) HOMO, and (iv) electron withdrawing substituents at the meso positions tend to maintain the common (d(xy))(2)(d(xz), d(yz))(3) ground state.
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Affiliation(s)
- T Ikeue
- Department of Chemistry, Toho University School of Medicine, Omorinishi, Ota-ku, Tokyo 143-8540
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17
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Ohta T, Matsuura K, Yoshizawa K, Morishima I. The electronic and vibrational structures of iron-oxo porphyrin with a methoxide or cysteinate axial ligand. J Inorg Biochem 2000; 82:141-52. [PMID: 11132621 DOI: 10.1016/s0162-0134(00)00162-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hybrid density functional theory (DFT) calculations for the electronic and vibrational structures of compound I species with a methoxide (MeO-) (1) or cysteinate (CysS-) (2) axial ligand are carried out in order to elucidate the natures of a methoxide-coordinating new type of compound I species (Bull. Chem. Soc. Jpn. 71 (1998) 1343) and cysteinate-coordinating compound I species of chloroperoxidase (CPO-I) and cytochrome P450s (P450-I). DFT computations of 1 and 2 demonstrate that these "anionic" ligands are a spin carrier; 70% (80%) of a spin density resides on the O (S) atom of the axial ligand and 30% (20%) is distributed on the porphyrin ring. These results suggest that for the generation of the compound I species, one electron is removed from the iron centers and the rest of the one electron is supplied from the oxidizable axial ligands instead of the iron centers or the porphyrin ring. Vibrational analyses demonstrate that the Fe=O bond is more strongly activated in 1 compared with 2 with the stretching mode at 849 cm(-1) (878 cm(-1)) for the doublet state1a (2a) and at 814 cm(-1) (875 cm(-1)) in the quartet state 1b (2b). This reverse order of the Fe=O bond strength with respect to the axial donor strength should have relevance to the significantly oxidized character of the CysS- axial ligand. In conjunction with the recent results of the extensive resonance Raman (RR) studies, some interpretations of unsettled RR results for compound I of chloroperoxidase (CPO-I) and a synthetic compound I species [O=FeIV(TMP*+)(alcohol)] (J. Am. Chem. Soc. 113 (1991) 6542) concerning the O=Fe stretching frequencies are discussed.
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Affiliation(s)
- T Ohta
- Department of Molecular Engineering, Kyoto University, Japan
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Schünemann V, Jung C, Trautwein AX, Mandon D, Weiss R. Intermediates in the reaction of substrate-free cytochrome P450cam with peroxy acetic acid. FEBS Lett 2000; 479:149-54. [PMID: 10981725 DOI: 10.1016/s0014-5793(00)01886-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Freeze-quenched intermediates of substrate-free cytochrome 57Fe-P450(cam) in reaction with peroxy acetic acid as oxidizing agent have been characterized by EPR and Mossbauer spectroscopy. After 8 ms of reaction time the reaction mixture consists of approximately 90% of ferric low-spin iron with g-factors and hyperfine parameters of the starting material; the remaining approximately 10% are identified as a free radical (S' = 1/2) by its EPR and as an iron(IV) (S= 1) species by its Mossbauer signature. After 5 min of reaction time the intermediates have disappeared and the Mossbauer and EPR-spectra exhibit 100% of the starting material. We note that the spin-Hamiltonian analysis of the spectra of the 8 ms reactant clearly reveals that the two paramagnetic species, e.g. the ferryl (iron(IV)) species and the radical, are not exchanged coupled. This led to the conclusion that under the conditions used, peroxy acetic acid oxidized a tyrosine residue (probably Tyr-96) into a tyrosine radical (Tyr*-96), and the iron(III) center of substrate-free P450(cam) to iron(IV).
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Affiliation(s)
- V Schünemann
- Institute of Physics, Medical University, Lübeck, Germany
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Neal TJ, Kang SJ, Turowska-Tyrk I, Schulz CE, Scheidt WR. Magnetic interactions in the high-spin iron(III) oxooctaethylchlorinato derivative [Fe(oxoOEC)(Cl)] and its pi-cation radical [Fe(oxoOEC.)(Cl)]SbCl6. Inorg Chem 2000; 39:872-80. [PMID: 12526364 DOI: 10.1021/ic991052w] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [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 beta-oxochlorin derivative [3,3,7,8,12,13,17,18-octaethyl-(3H)-porphin-2-onato(2-)]iron(III) chloride, [Fe(oxoOEC)(Cl)], and its pi-cation radical derivative [Fe(oxoOEC.)(Cl)]SbCl6 is described. Both compounds have been characterized by single-crystal X-ray structure determinations, IR, UV/vis/near-IR, and Mössbauer spectroscopies, and temperature-dependent magnetic susceptibility measurements. The macrocycles of [Fe(oxoOEC)(Cl)] and [Fe(oxoOEC.)(Cl)]SbCl6 are both saddled, and [Fe(oxoOEC.)(Cl)]-SbCl6 is slightly ruffled as well. [Fe(oxoOEC)(Cl)] shows a laterally shifted dimeric unit in the solid state, with a mean plane separation of 3.39 A and a lateral shift of 7.39 A. Crystal data for [Fe(oxoOEC)(Cl)]: triclinic, space group P1, Z = 2, a = 9.174(2) A, b = 13.522(3) A, c = 14.838(3) A, alpha = 95.79(3) degrees, beta = 101.46(2) degrees, gamma = 104.84(3) degrees. Upon oxidation, the inter-ring geometric parameters increase; the mean plane separation and the lateral shift of the dimeric unit of [Fe(oxoOEC.)(Cl)]SbCl6 are 4.82 and 8.79 A, respectively. Crystal data for [Fe(oxoOEC.)(Cl)]SbCl6: monoclinic, space group Cc, Z = 4, a = 19.8419(13) A, b = 10.027(2) A, c = 22.417(4) A, beta = 96.13(2) degrees. A broad near-IR absorption band appears at 1415 nm for the pi-cation radical, [Fe(oxoOEC.)(Cl)]SbCl6. Zero-field Mössbauer measurements at 4.2 K for both [Fe(oxoOEC)(Cl)] and [Fe(oxoOEC.)(Cl)]SbCl6 confirmed that the oxidation state of the iron atom did not change upon chemical oxidation. Solid-state magnetic susceptibility measurements for [Fe(oxoOEC.)(Cl)]SbCl6 resulted in a large temperature dependence of the magnetic moment that can best be fit with a model that includes a zero-field splitting parameter of D = 6 cm-1, antiferromagnetic intermolecular iron-iron coupling (2JFe-Fe = -0.14 cm-1), antiferromagnetic intramolecular iron-radical coupling (2JFe-r = -76 cm-1), and antiferromagnetic radical-radical coupling (2Jr-r = -13 cm-1).
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Affiliation(s)
- T J Neal
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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21
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Satoh M, Ohba Y, Hoshino M, Konishi S, Ebina F, Yamauchi S, Iwaizumi M. Electronic States and Magnetic Properties of Triplet Porphyrinato Copper(II) Cation Radical Complexes. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1999. [DOI: 10.1246/bcsj.72.2389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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22
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Murakami T, Yamaguchi K, Watanabe Y, Morishima I. A New Active Intermediate in Monooxygenations Catalyzed by Iron Porphyrin Complexes. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1998. [DOI: 10.1246/bcsj.71.1343] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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23
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Strachan JP, Gentemann S, Seth J, Kalsbeck WA, Lindsey JS, Holten D, Bocian DF. Synthesis and Characterization of Tetrachlorodiarylethyne-Linked Porphyrin Dimers. Effects of Linker Architecture on Intradimer Electronic Communication. Inorg Chem 1998; 37:1191-1201. [PMID: 11670323 DOI: 10.1021/ic970967c] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effects of incorporating chloro groups at all ortho positions of a diphenylethyne linker that bridges the zinc and free base (Fb) components of a porphyrin dimer (ZnFbB(Cl(4))) have been investigated in detail via various static and time-resolved spectroscopic methods. The excited-state energy-transfer rate in ZnFbB(Cl(4)) ((134 ps)(-)(1)) is 5-fold slower than that in the corresponding dimer having an unsubstituted linker (ZnFbU, (24 ps)(-)(1)) but is only modestly slower than that in the dimer having o-methyl groups on the linker (ZnFbB(CH(3))(4), (115 ps)(-)(1)). The ground-state hole/electron-hopping rates in the oxidized bis-Zn analogues of all three dimers are much slower than the excited-state energy-transfer rates. There is no discernible difference between the hole/electron-hopping rates in the o-chloro- and o-methyl-substituted arrays. The similar ground- and excited-state dynamics observed for the o-chloro- and o-methyl-substituted arrays is attributed to the dominance of torsional constraints in mediating the extent of through-bond electronic communication. These constraints attenuate intradimer communication by restricting the rotation toward coplanarity of the phenyl rings of the linker and the porphyrin rings. Thus, the o-chloro groups on the linker decrease electronic communication via a steric, rather than purely electronic, mechanism.
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Affiliation(s)
- Jon-Paul Strachan
- Departments of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, Washington University, St. Louis, Missouri 63130-4899, and University of California, Riverside, California 92521-0403
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Sibilia SA, Czernuszewicz RS, Crossley MJ, Spiro TG. Orbital Ordering in β-Substituted Porphyrins: Resonance Raman Spectra of the Radical Cations. Inorg Chem 1997. [DOI: 10.1021/ic970562s] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sharon A. Sibilia
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544
| | | | | | - Thomas G. Spiro
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544
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25
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Kuramochi H, Noodleman L, Case DA. Density Functional Study on the Electronic Structures of Model Peroxidase Compounds I and II. J Am Chem Soc 1997. [DOI: 10.1021/ja970574c] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hiroshi Kuramochi
- Contribution from the Department of Molecular Biology, TPC15, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
| | - Louis Noodleman
- Contribution from the Department of Molecular Biology, TPC15, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
| | - David A. Case
- Contribution from the Department of Molecular Biology, TPC15, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
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Renner MW, Barkigia KM, Fajer J. Conformational landscapes of nonplanar porphyrins: superstructure, ligation, binding pockets and oxidation effects in Cu(II) porphyrins. Inorganica Chim Acta 1997. [DOI: 10.1016/s0020-1693(97)05570-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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27
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Oxidation of polycyclic aromatic hydrocarbons by an oxoferryl porphyrin π-cation radical. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s1381-1169(97)00053-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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28
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Jayaraj K, Gold A, Austin RN, Ball LM, Terner J, Mandon D, Weiss R, Fischer J, DeCian A, Bill E, Müther M, Schünemann V, Trautwein AX. Compound I and Compound II Analogues from Porpholactones. Inorg Chem 1997; 36:4555-4566. [PMID: 11670121 DOI: 10.1021/ic970597s] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The tetraaza macrocycles 2-oxa-3-oxotetramesitylporphine (|H(2) 1|) and 2-oxa-3-oxotetrakis(2,6-dichlorophenyl)porphine (|H(2) 2|) and the corresponding iron complexes (|Fe(III)(X) 1| and |Fe(III)(X) 2|; X= Cl(-), OH(-), or SO(3)CF(3)(-)) have been synthesized. These macrocycles are derived from porphyrins by transformation of one pyrrole ring to an oxazolone ring. The resulting lactone functionality serves to restrict but not completely block pi-conjugation around the periphery. These complexes thus share properties with both porphyrins and chlorins. The ferric and high-valent iron complexes have been characterized by a variety of spectroscopic techniques. The molecular structure of |Fe(III)(Cl) 2| has been obtained by X-ray crystallography and shows that the structural changes at the macrocycle periphery do not perturb the coordination sphere of iron relative to the corresponding porphyrin complexes. This is illustrated by the observation that Fe-O frequencies in the resonance Raman spectra of the porpholactone analogues of compounds I and II are not substantially different from those of porphyrins and by the axial appearance of the EPR signals of the high-spin ferric complexes. This is consistent with reports that the Fe=O unit of oxidized porphyrins and chlorins is relatively insensitive to alteration of macrocycle symmetry. Nevertheless, probes of properties of the porpholactone macrocycle ((1)H NMR, resonance Raman skeletal modes) show effects of the asymmetry induced by the oxazolone ring. On the basis of (1)H NMR, EPR, Mössbauer, and resonance Raman data, the singly occupied molecular orbital of oxoferryl porpholactone pi-cation radicals correlates with the a(1u) molecular orbital of porphyrins under D(4)(h)() symmetry. Moreover, the paramagnetic properties and the intramolecular exchange interaction of ferryl iron and the porpholactone pi-radical have been characterized by EPR and magnetic Mössbauer measurements and spin-Hamiltonian analyses. The values J(0) = 17 cm(-)(1) and J(0) = 11 cm(-)(1) obtained for the exchange coupling constants of the oxoferryl porpholactone pi-cation radical complexes |Fe(IV)=O 1|(+) and |Fe(IV)=O 2|(+), respectively, are among the lowest found for synthetic compound I analogues.
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Affiliation(s)
- K. Jayaraj
- Institut für Physik, Medizinische Universität zu Lübeck, D-23538 Lübeck, Germany
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Sibilia SA, Hu S, Piffat C, Melamed D, Spiro TG. Metal Dependence of the Highest Occupied Molecular Orbital in Sterically Hindered Octaethyltetraphenylporphyrins. Inorg Chem 1997; 36:1013-1019. [PMID: 11669663 DOI: 10.1021/ic960774+] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Resonance Raman (RR) spectra are reported for nickel(II) and copper(II) 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin (MOETPP) cation radicals in order to examine the influence of the substituent pattern and of out-of-plane distortions on the character of the porphyrin frontier orbitals. Isotopic frequency shifts ((13)C(m), (15)N, d(20)) were used to secure assignments of the RR bands. The highest occupied molecular orbital was found to switch from a(2u) to a(1u) between CuOETPP(+) and NiOETPP(+) as evidenced by (1) opposite shifts in the C(beta)C(beta) stretching mode, nu(2), and (2) selective enhancement of phenyl modes in CuOETPP(+) vs ethyl modes in NiOETPP(+). However, the nu(2) shifts are smaller than those seen in NiOEP(+) (A(1u)) or CuTPP(+) (A(2u)), indicating that mixing of the A(1u) and A(2u) states is greater in the OETPP(+) radicals. A greater amount of mixing in OETPP(+) is consistent with a small energy gap between the two states and with the out-of-plane distortion. The dominant mixing mechanism is a bond alternant (A(2g)) distortion, which is evident in the CuOETPP crystal structure and in the appearance of anomalously polarized bands in the Soret-enhanced radical cation RR spectra. Intensity analysis of the absorption spectra supports the inference of orbital switching between NiOETPP and CuOETPP but also indicates an increased energy gap between the two metals, relative to OEP and TPP. This increase in metal sensitivity is attributable to the out-of-plane distortions observed in Ni- and CuOETPP.
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Affiliation(s)
- Sharon A. Sibilia
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544
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Schulz CE, Song H, Mislankar A, Orosz RD, Reed CA, Debrunner PG, Scheidt WR. [Fe(OEP•)(X)]+ π-Cation Radicals: Characterization and Spin−Spin Interactions. Inorg Chem 1997. [DOI: 10.1021/ic961053d] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Charles E. Schulz
- Departments of Physics, Knox College, Galesburg, Illinois 61401, and University of Illinois, Urbana, Illinois 61801, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, and Department of Chemistry, University of Southern California, Los Angeles, California 90089-0744
| | - Hungsun Song
- Departments of Physics, Knox College, Galesburg, Illinois 61401, and University of Illinois, Urbana, Illinois 61801, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, and Department of Chemistry, University of Southern California, Los Angeles, California 90089-0744
| | - Anil Mislankar
- Departments of Physics, Knox College, Galesburg, Illinois 61401, and University of Illinois, Urbana, Illinois 61801, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, and Department of Chemistry, University of Southern California, Los Angeles, California 90089-0744
| | - Robert D. Orosz
- Departments of Physics, Knox College, Galesburg, Illinois 61401, and University of Illinois, Urbana, Illinois 61801, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, and Department of Chemistry, University of Southern California, Los Angeles, California 90089-0744
| | - Christopher A. Reed
- Departments of Physics, Knox College, Galesburg, Illinois 61401, and University of Illinois, Urbana, Illinois 61801, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, and Department of Chemistry, University of Southern California, Los Angeles, California 90089-0744
| | - Peter G. Debrunner
- Departments of Physics, Knox College, Galesburg, Illinois 61401, and University of Illinois, Urbana, Illinois 61801, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, and Department of Chemistry, University of Southern California, Los Angeles, California 90089-0744
| | - W. Robert Scheidt
- Departments of Physics, Knox College, Galesburg, Illinois 61401, and University of Illinois, Urbana, Illinois 61801, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, and Department of Chemistry, University of Southern California, Los Angeles, California 90089-0744
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Kalsbeck WA, Seth J, Bocian DF. Evidence for Porphyrin (π)−Chlorine (p) Orbital Overlap in the π-Cation Radicals of Zinc(II) and Magnesium(II) Tetrakis(o-dichlorophenyl)porphyrin. Inorg Chem 1996. [DOI: 10.1021/ic9608354] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- William A. Kalsbeck
- Department of Chemistry, University of California, Riverside, California 92521-0403
| | - Jyoti Seth
- Department of Chemistry, University of California, Riverside, California 92521-0403
| | - David F. Bocian
- Department of Chemistry, University of California, Riverside, California 92521-0403
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Nakano T, Agatsuma N, Kodama S, Kakuda H, Dolphin D. A Biomimetic Study of Cytochrome P450 Related Oxidations of Toluenes Using Synthetic Hemin. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1996. [DOI: 10.1246/bcsj.69.3513] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Molecular Structure of the Chloroiron(III) Derivative of themeso-Unsubstituted 2,7,12,17-Tetramethyl-3,8,13,18-tetramesitylporphyrin and Weak Ferromagnetic Exchange Interactions in the A1u Oxoiron(IV) Porphyrin π Radical Cation Complex. Chemistry 1996. [DOI: 10.1002/chem.19960020919] [Citation(s) in RCA: 18] [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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