1
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Hurdax P, Kern CS, Boné TG, Haags A, Hollerer M, Egger L, Yang X, Kirschner H, Gottwald A, Richter M, Bocquet F, Soubatch S, Koller G, Tautz FS, Sterrer M, Puschnig P, Ramsey MG. Large Distortion of Fused Aromatics on Dielectric Interlayers Quantified by Photoemission Orbital Tomography. ACS NANO 2022; 16:17435-17443. [PMID: 36239301 PMCID: PMC9620409 DOI: 10.1021/acsnano.2c08631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/12/2022] [Indexed: 06/16/2023]
Abstract
Polycyclic aromatic compounds with fused benzene rings offer an extraordinary versatility as next-generation organic semiconducting materials for nanoelectronics and optoelectronics due to their tunable characteristics, including charge-carrier mobility and optical absorption. Nonplanarity can be an additional parameter to customize their electronic and optical properties without changing the aromatic core. In this work, we report a combined experimental and theoretical study in which we directly observe large, geometry-induced modifications in the frontier orbitals of a prototypical dye molecule when adsorbed on an atomically thin dielectric interlayer on a metallic substrate. Experimentally, we employ angle-resolved photoemission experiments, interpreted in the framework of the photoemission orbital tomography technique. We demonstrate its sensitivity to detect geometrical bends in adsorbed molecules and highlight the role of the photon energy used in experiment for detecting such geometrical distortions. Theoretically, we conduct density functional calculations to determine the geometric and electronic structure of the adsorbed molecule and simulate the photoemission angular distribution patterns. While we found an overall good agreement between experimental and theoretical data, our results also unveil limitations in current van der Waals corrected density functional approaches for such organic/dielectric interfaces. Hence, photoemission orbital tomography provides a vital experimental benchmark for such systems. By comparison with the state of the same molecule on a metallic substrate, we also offer an explanation why the adsorption on the dielectric induces such large bends in the molecule.
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Affiliation(s)
- Philipp Hurdax
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Christian S. Kern
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Thomas Georg Boné
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Anja Haags
- Peter
Grünberg Institute (PGI-3), Forschungszentrum
Jülich, 52425Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425Jülich, Germany
- Experimentalphysik
IV A, RWTH Aachen University, 52074Aachen, Germany
| | - Michael Hollerer
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Larissa Egger
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Xiaosheng Yang
- Peter
Grünberg Institute (PGI-3), Forschungszentrum
Jülich, 52425Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425Jülich, Germany
- Experimentalphysik
IV A, RWTH Aachen University, 52074Aachen, Germany
| | - Hans Kirschner
- Physikalisch-Technische
Bundesanstalt (PTB), 10587Berlin, Germany
| | | | - Mathias Richter
- Physikalisch-Technische
Bundesanstalt (PTB), 10587Berlin, Germany
| | - François
C. Bocquet
- Peter
Grünberg Institute (PGI-3), Forschungszentrum
Jülich, 52425Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425Jülich, Germany
| | - Serguei Soubatch
- Peter
Grünberg Institute (PGI-3), Forschungszentrum
Jülich, 52425Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425Jülich, Germany
| | - Georg Koller
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Frank Stefan Tautz
- Peter
Grünberg Institute (PGI-3), Forschungszentrum
Jülich, 52425Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425Jülich, Germany
- Experimentalphysik
IV A, RWTH Aachen University, 52074Aachen, Germany
| | - Martin Sterrer
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Peter Puschnig
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
| | - Michael G. Ramsey
- Institute
of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010Graz, Austria
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2
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Leipzig BK, Rees JA, Kowalska JK, Theisen RM, Kavčič M, Poon PCY, Kaminsky W, DeBeer S, Bill E, Kovacs JA. How Do Ring Size and π-Donating Thiolate Ligands Affect Redox-Active, α-Imino-N-heterocycle Ligand Activation? Inorg Chem 2018; 57:1935-1949. [PMID: 29411979 DOI: 10.1021/acs.inorgchem.7b02748] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Considerable effort has been devoted to the development of first-row transition-metal catalysts containing redox-active imino-pyridine ligands that are capable of storing multiple reducing equivalents. This property allows abundant and inexpensive first-row transition metals, which favor sequential one-electron redox processes, to function as competent catalysts in the concerted two-electron reduction of substrates. Herein we report the syntheses and characterization of a series of iron complexes that contain both π-donating thiolate and π-accepting (α-imino)-N-heterocycle redox-active ligands, with progressively larger N-heterocycle rings (imidazole, pyridine, and quinoline). A cooperative interaction between these complementary redox-active ligands is shown to dictate the properties of these complexes. Unusually intense charge-transfer (CT) bands, and intraligand metrical parameters, reminiscent of a reduced (α-imino)-N-heterocycle ligand (L•-), initially suggested that the electron-donating thiolate had reduced the N-heterocycle. Sulfur K-edge X-ray absorption spectroscopic (XAS) data, however, provides evidence for direct communication, via backbonding, between the thiolate sulfur and the formally orthogonal (α-imino)-N-heterocycle ligand π*-orbitals. DFT calculations provide evidence for extensive delocalization of bonds over the sulfur, iron, and (α-imino)-N-heterocycle, and TD-DFT shows that the intense optical CT bands involve transitions between a mixed Fe/S donor, and (α-imino)-N-heterocycle π*-acceptor orbital. The energies and intensities of the optical and S K-edge pre-edge XAS transitions are shown to correlate with N-heterocycle ring size, as do the redox potentials. When the thiolate is replaced with a thioether, or when the low-spin S = 0 Fe(II) is replaced with a high-spin S = 3/2 Co(II), the N-heterocycle ligand metrical parameters and electronic structure do not change relative to the neutral L0 ligand. With respect to the development of future catalysts containing redox-active ligands, the energy cost of storing reducing equivalents is shown to be lowest when a quinoline, as opposed to imidazole or pyridine, is incorporated into the ligand backbone of the corresponding Fe complex.
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Affiliation(s)
- Benjamin K Leipzig
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Julian A Rees
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Joanna K Kowalska
- Max Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Roslyn M Theisen
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | | | | | - Werner Kaminsky
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Julie A Kovacs
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
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3
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Wu Y, Chang C, Wang C, Hsieh C, Horng Y. C=N Bond Activation and Hydration by an Iron(III) Complex with Asymmetric Sulfur Oxygenation. Eur J Inorg Chem 2017. [DOI: 10.1002/ejic.201601565] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yun‐Ru Wu
- Department of Chemistry National Changhua University of Education 50058 Changhua Taiwan
| | - Chia‐Ming Chang
- Department of Chemistry National Changhua University of Education 50058 Changhua Taiwan
| | - Chia‐Chi Wang
- Department of Chemistry National Changhua University of Education 50058 Changhua Taiwan
| | - Chang‐Chih Hsieh
- Department of Chemistry National Changhua University of Education 50058 Changhua Taiwan
| | - Yih‐Chern Horng
- Department of Chemistry National Changhua University of Education 50058 Changhua Taiwan
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4
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Liang HW, Kroll T, Nordlund D, Weng TC, Sokaras D, Pierpont CG, Gaffney KJ. Charge and Spin-State Characterization of Cobalt Bis(o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies. Inorg Chem 2016; 56:737-747. [DOI: 10.1021/acs.inorgchem.6b01666] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- H. Winnie Liang
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
- PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Thomas Kroll
- Stanford Synchrotron Radiation Lightsource (SSRL), SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Dennis Nordlund
- Stanford Synchrotron Radiation Lightsource (SSRL), SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Tsu-Chien Weng
- Center for High Pressure Science & Technology Advanced Research, Pudong, Shanghai 201203, P. R. China
| | - Dimosthenis Sokaras
- Stanford Synchrotron Radiation Lightsource (SSRL), SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Cortlandt G. Pierpont
- Department
of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Kelly J. Gaffney
- PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Stanford Synchrotron Radiation Lightsource (SSRL), SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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5
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Villar-Acevedo G, Lugo-Mas P, Blakely MN, Rees JA, Ganas AS, Hanada EM, Kaminsky W, Kovacs JA. Metal-Assisted Oxo Atom Addition to an Fe(III) Thiolate. J Am Chem Soc 2016; 139:119-129. [PMID: 28033001 DOI: 10.1021/jacs.6b03512] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cysteinate oxygenation is intimately tied to the function of both cysteine dioxygenases (CDOs) and nitrile hydratases (NHases), and yet the mechanisms by which sulfurs are oxidized by these enzymes are unknown, in part because intermediates have yet to be observed. Herein, we report a five-coordinate bis-thiolate ligated Fe(III) complex, [FeIII(S2Me2N3(Pr,Pr))]+ (2), that reacts with oxo atom donors (PhIO, IBX-ester, and H2O2) to afford a rare example of a singly oxygenated sulfenate, [FeIII(η2-SMe2O)(SMe2)N3(Pr,Pr)]+ (5), resembling both a proposed intermediate in the CDO catalytic cycle and the essential NHase Fe-S(O)Cys114 proposed to be intimately involved in nitrile hydrolysis. Comparison of the reactivity of 2 with that of a more electron-rich, crystallographically characterized derivative, [FeIIIS2Me2NMeN2amide(Pr,Pr)]- (8), shows that oxo atom donor reactivity correlates with the metal ion's ability to bind exogenous ligands. Density functional theory calculations suggest that the mechanism of S-oxygenation does not proceed via direct attack at the thiolate sulfurs; the average spin-density on the thiolate sulfurs is approximately the same for 2 and 8, and Mulliken charges on the sulfurs of 8 are roughly twice those of 2, implying that 8 should be more susceptible to sulfur oxidation. Carboxamide-ligated 8 is shown to be unreactive towards oxo atom donors, in contrast to imine-ligated 2. Azide (N3-) is shown to inhibit sulfur oxidation with 2, and a green intermediate is observed, which then slowly converts to sulfenate-ligated 5. This suggests that the mechanism of sulfur oxidation involves initial coordination of the oxo atom donor to the metal ion. Whether the green intermediate is an oxo atom donor adduct, Fe-O═I-Ph, or an Fe(V)═O remains to be determined.
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Affiliation(s)
- Gloria Villar-Acevedo
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Priscilla Lugo-Mas
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Maike N Blakely
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Julian A Rees
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Abbie S Ganas
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Erin M Hanada
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Werner Kaminsky
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
| | - Julie A Kovacs
- The Department of Chemistry, University of Washington , Box 351700, Seattle, Washington 98195-1700, United States
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6
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Li N, Jin Y, Xue LZ, Li PY, Yan DY, Zhu XY. 188Re-labeled hyperbranched polysulfonamine as a robust tool for targeted cancer diagnosis and radioimmunotherapy. CHINESE JOURNAL OF POLYMER SCIENCE 2013. [DOI: 10.1007/s10118-013-1242-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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7
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The Active Site of Nitrile Hydratase: An Assembly of Unusual Coordination Features by Nature. MOLECULAR DESIGN IN INORGANIC BIOCHEMISTRY 2013. [DOI: 10.1007/430_2012_85] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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8
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Coggins MK, Toledo S, Shaffer E, Kaminsky W, Shearer J, Kovacs JA. Characterization and dioxygen reactivity of a new series of coordinatively unsaturated thiolate-ligated manganese(II) complexes. Inorg Chem 2012; 51:6633-44. [PMID: 22642272 DOI: 10.1021/ic300192q] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis, structural, and spectroscopic characterization of four new coordinatively unsaturated mononuclear thiolate-ligated manganese(II) complexes ([Mn(II)(S(Me2)N(4)(6-Me-DPEN))](BF(4)) (1), [Mn(II)(S(Me2)N(4)(6-Me-DPPN))](BPh(4))·MeCN (3), [Mn(II)(S(Me2)N(4)(2-QuinoPN))](PF(6))·MeCN·Et(2)O (4), and [Mn(II)(S(Me2)N(4)(6-H-DPEN)(MeOH)](BPh(4)) (5)) is described, along with their magnetic, redox, and reactivity properties. These complexes are structurally related to recently reported [Mn(II)(S(Me2)N(4)(2-QuinoEN))](PF(6)) (2) (Coggins, M. K.; Kovacs, J. A. J. Am. Chem. Soc.2011, 133, 12470). Dioxygen addition to complexes 1-5 is shown to result in the formation of five new rare examples of Mn(III) dimers containing a single, unsupported oxo bridge: [Mn(III)(S(Me2)N(4)(6-Me-DPEN)](2)-(μ-O)(BF(4))(2)·2MeOH (6), [Mn(III)(S(Me2)N(4)(QuinoEN)](2)-(μ-O)(PF(6))(2)·Et(2)O (7), [Mn(III)(S(Me2)N(4)(6-Me-DPPN)](2)-(μ-O)(BPh(4))(2) (8), [Mn(III)(S(Me2)N(4)(QuinoPN)](2)-(μ-O)(BPh(4))(2) (9), and [Mn(III)(S(Me2)N(4)(6-H-DPEN)](2)-(μ-O)(PF(6))(2)·2MeCN (10). Labeling studies show that the oxo atom is derived from (18)O(2). Ligand modifications, involving either the insertion of a methylene into the backbone or the placement of an ortho substituent on the N-heterocyclic amine, are shown to noticeably modulate the magnetic and reactivity properties. Fits to solid-state magnetic susceptibility data show that the Mn(III) ions of μ-oxo dimers 6-10 are moderately antiferromagnetically coupled, with coupling constants (2J) that fall within the expected range. Metastable intermediates, which ultimately convert to μ-oxo bridged 6 and 7, are observed in low-temperature reactions between 1 and 2 and dioxygen. Complexes 3-5, on the other hand, do not form observable intermediates, thus illustrating the effect that relatively minor ligand modifications have upon the stability of metastable dioxygen-derived species.
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Affiliation(s)
- Michael K Coggins
- The Department of Chemistry, University of Washington, Campus Box 351700, Seattle, Washington 98195-1700, USA
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9
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Saha R, Biswas S, Steele IM, Dey K, Mostafa G. A supramolecular spin crossover Fe(III) complex and its Cr(III) isomer: stabilization of water-chloride cluster within supramolecular host. Dalton Trans 2011; 40:3166-75. [PMID: 21340091 DOI: 10.1039/c0dt01256d] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The metal complexes, [M(Hdammthiol)(2)]Cl·3H(2)O [M = Cr(III) (1), Fe(III) (2)] [where H(2)dammthiol is the thiol form of the ligand, diacetylmonoxime morpholine N-thiohydrazone] were synthesized by metal template reactions of diacetylemonoxime with morpholine N-thiohydrazide in the presence of CrCl(3)·6H(2)O and FeCl(3)·6H(2)O. Both the complexes (1 and 2) were characterized by single crystal X-ray crystallography, spectroscopic (IR and UV-vis), Mössbauer and TGA analyses. The single crystal X-ray studies of both complexes show that the supramolecular hosts, constructed by the discrete mononuclear complexes, form supramolecular channels along the c-axis which are filled up by water-chloride clusters. In both complexes, the 1D water-chloride chain with chair-like architecture within the supramolecular hosts presents novelty. The magnetic measurement study of Fe(III) complex shows a spin crossover from S = 1/2 at 2.5 K to S = 5/2 at 300 K. At very low temperature, the presence of strong cooperative hydrogen bonding interactions stabilizes the S = 1/2 state.
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Affiliation(s)
- Rajat Saha
- Department of Physics, Jadavpur University, Jadavpur, Kolkata-700032, India
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10
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Galardon E, Tomas A, Selkti M, Roussel P, Artaud I. Synthesis, Characterization, and Reactivity of Alkyldisulfanido Zinc Complexes. Inorg Chem 2009; 48:5921-7. [DOI: 10.1021/ic900238v] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Erwan Galardon
- Laboratoire de Chimie et Biochimie Pharmacologique et Toxicologique, UMR 8601 CNRS, Université Paris Descartes, 45 rue des Saints Pères, 75270 Paris cedex 06, France
| | - Alain Tomas
- Laboratoire de Cristallographie et RMN Biologiques, UMR 8015 CNRS, Université Paris Descartes, 4 avenue de l’Observatoire, 75270 Paris cedex 06, France
| | - Mohamed Selkti
- Laboratoire de Cristallographie et RMN Biologiques, UMR 8015 CNRS, Université Paris Descartes, 4 avenue de l’Observatoire, 75270 Paris cedex 06, France
| | - Pascal Roussel
- UCCS − Unité de Catalyse et Chimie du Solide, UMR 8012 CNRS, École Nationale Supérieure de Chimie de Lille BP 90108 − 59652 Villeneuve d’Ascq cedex, France
| | - Isabelle Artaud
- Laboratoire de Chimie et Biochimie Pharmacologique et Toxicologique, UMR 8601 CNRS, Université Paris Descartes, 45 rue des Saints Pères, 75270 Paris cedex 06, France
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11
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Lugo-Mas P, Taylor W, Schweitzer D, Theisen RM, Xu L, Shearer J, Swartz RD, Gleaves MC, Dipasquale A, Kaminsky W, Kovacs JA. Properties of square-pyramidal alkyl-thiolate Fe(III) complexes, including an analogue of the unmodified form of nitrile hydratase. Inorg Chem 2008; 47:11228-36. [PMID: 18989922 PMCID: PMC2659597 DOI: 10.1021/ic801704n] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The syntheses and structures of three new coordinatively unsaturated, monomeric, square-pyramidal thiolate-ligated Fe(III) complexes are described, [Fe(III)((tame-N(3))S(2)(Me2))](+) (1), [Fe(III)(Et-N(2)S(2)(Me2))(py)](1-) (3), and [Fe(III)((tame-N(2)S)S(2)(Me2))](2-) (15). The anionic bis-carboxamide, tris-thiolate N(2)S(3) coordination sphere of 15 is potentially similar to that of the yet-to-be characterized unmodified form of NHase. Comparison of the magnetic and reactivity properties of these reveals how anionic charge build up (from cationic 1 to anionic 3 and dianionic 15) and spin-state influence apical ligand affinity. For all of the ligand-field combinations examined, an intermediate S = 3/2 spin state was shown to be favored by a strong N(2)S(2) basal plane ligand field, and this was found to reduce the affinity for apical ligands, even when they are built in. This is in contrast to the post-translationally modified NHase active site, which is low spin and displays a higher affinity for apical ligands. Cationic 1 and its reduced Fe(II) precursor are shown to bind NO and CO, respectively, to afford [Fe(III)((tame-N(3))S(2)(Me))(NO)](+) (18, nu(NuO) = 1865 cm(-1)), an analogue of NO-inactivated NHase, and [Fe(II)((tame-N(3))S(2)(Me))(CO)] (16; nu(CO) stretch (1895 cm(-1)). Anions (N(3)(-), CN(-)) are shown to be unreactive toward 1, 3, and 15 and neutral ligands unreactive toward 3 and 15, even when present in 100-fold excess and at low temperatures. The curtailed reactivity of 15, an analogue of the unmodified form of NHase, and its apical-oxygenated S = 3/2 derivative [Fe(III)((tame-N(2)SO(2))S(2)(Me2))](2-) (20) suggests that regioselective post-translational oxygenation of the basal plane NHase cysteinate sulfurs plays an important role in promoting substrate binding. This is supported by previously reported theoretical (DFT) calculations.
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Affiliation(s)
- Priscilla Lugo-Mas
- The Department of Chemistry, University of Washington, Box 351700 Seattle, Washington 98195-1700, USA
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12
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Tennyson AG, Dhar S, Lippard SJ. Synthesis and Characterization of {Ni(NO)}10and {Co(NO)2}10Complexes Supported by Thiolate Ligands. J Am Chem Soc 2008; 130:15087-98. [DOI: 10.1021/ja803992y] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Andrew G. Tennyson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Shanta Dhar
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Stephen J. Lippard
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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13
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Yano T, Ozawa T, Masuda H. Structural and Functional Model Systems for Analysis of the Active Center of Nitrile Hydratase. CHEM LETT 2008. [DOI: 10.1246/cl.2008.672] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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14
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Brines LM, Shearer J, Fender JK, Schweitzer D, Shoner SC, Barnhart D, Kaminsky W, Lovell S, Kovacs JA. Periodic trends within a series of five-coordinate thiolate-ligated [MII(SMe2N4(tren))]+ (M = Mn, Fe, Co, Ni, Cu, Zn) complexes, including a rare example of a stable CuII-thiolate. Inorg Chem 2007; 46:9267-77. [PMID: 17867686 PMCID: PMC2532082 DOI: 10.1021/ic701433p] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of five-coordinate thiolate-ligated complexes [M(II)(tren)N4S(Me2)]+ (M = Mn, Fe, Co, Ni, Cu, Zn; tren = tris(2-aminoethyl)amine) are reported, and their structural, electronic, and magnetic properties are compared. Isolation of dimeric [Ni(II)(SN4(tren)-RS(dang))]2 ("dang"= dangling, uncoordinated thiolate supported by H bonds), using the less bulky [(tren)N4S](1-) ligand, pointed to the need for gem-dimethyls adjacent to the sulfur to sterically prevent dimerization. All of the gem-dimethyl derivatized complexes are monomeric and, with the exception of [Ni(II)(S(Me2)N4(tren)]+, are isostructural and adopt a tetragonally distorted trigonal bipyramidal geometry favored by ligand constraints. The nickel complex uniquely adopts an approximately ideal square pyramidal geometry and resembles the active site of Ni-superoxide dismutase (Ni-SOD). Even in coordinating solvents such as MeCN, only five-coordinate structures are observed. The MII-S thiolate bonds systematically decrease in length across the series (Mn-S > Fe-S > Co-S > Ni-S approximately Cu-S < Zn-S) with exceptions occurring upon the occupation of sigma* orbitals. The copper complex, [Cu(II)(S(Me2)N4(tren)]+, represents a rare example of a stable CuII-thiolate, and models the perturbed "green" copper site of nitrite reductase. In contrast to the intensely colored, low-spin Fe(III)-thiolates, the M(II)-thiolates described herein are colorless to moderately colored and high-spin (in cases where more than one spin-state is possible), reflecting the poorer energy match between the metal d- and sulfur orbitals upon reduction of the metal ion. As the d-orbitals drop in energy proceeding across the across the series M(2+) (M= Mn, Fe, Co, Ni, Cu), the sulfur-to-metal charge-transfer transition moves into the visible region, and the redox potentials cathodically shift. The reduced M(+1) oxidation state is only accessible with copper, and the more oxidized M(+4) oxidation state is only accessible for manganese.
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Affiliation(s)
- Lisa M. Brines
- The Department of Chemistry, University of Washington: Box 351700 Seattle, WA 98195-1700
| | - Jason Shearer
- The Department of Chemistry, University of Washington: Box 351700 Seattle, WA 98195-1700
| | - Jessica K. Fender
- The Department of Chemistry, University of Washington: Box 351700 Seattle, WA 98195-1700
| | - Dirk Schweitzer
- The Department of Chemistry, University of Washington: Box 351700 Seattle, WA 98195-1700
| | - Steven C. Shoner
- The Department of Chemistry, University of Washington: Box 351700 Seattle, WA 98195-1700
| | | | | | | | - Julie A. Kovacs
- The Department of Chemistry, University of Washington: Box 351700 Seattle, WA 98195-1700
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15
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Kovacs JA, Brines LM. Understanding how the thiolate sulfur contributes to the function of the non-heme iron enzyme superoxide reductase. Acc Chem Res 2007; 40:501-9. [PMID: 17536780 PMCID: PMC3703784 DOI: 10.1021/ar600059h] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Toxic superoxide radicals, generated via adventitious reduction of dioxygen, have been implicated in a number of disease states. The cysteinate-ligated non-heme iron enzyme superoxide reductase (SOR) degrades superoxide via reduction. Biomimetic analogues which provide insight into why nature utilizes a trans-thiolate to promote SOR function are described. Spectroscopic and/or structural characterization of the first examples of thiolate-ligated Fe (III)-peroxo complexes provides important benchmark parameters for the identification of biological intermediates. Oxidative addition of superoxide is favored by low redox potentials. The trans influence of the thiolate appears to significantly weaken the Fe-O peroxo bond, favoring proton-induced release of H 2O 2 from a high-spin Fe(III)-OOH complex.
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Affiliation(s)
- Julie A Kovacs
- The Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, USA
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16
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Morgado CA, Mcnamara JP, Hillier * IH, Sundararajan M. The structure and spin-states of some Fe(III) mimics of nitrile hydratase, studied by DFT and ONIOM(DFT:PM3) calculations. Mol Phys 2005. [DOI: 10.1080/00268970512331340583] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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17
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Ozawa T, Ikeda T, Yano T, Arii H, Yamaguchi S, Funahashi Y, Jitsukawa K, Masuda H. Coordination of a Water Molecule to a Square-pyramidal N2S3-type Co(III) Complex Directed to an Active Site of Nitrile Hydratase. CHEM LETT 2005. [DOI: 10.1246/cl.2005.18] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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18
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Kovacs JA. Synthetic analogues of cysteinate-ligated non-heme iron and non-corrinoid cobalt enzymes. Chem Rev 2004; 104:825-48. [PMID: 14871143 PMCID: PMC4487544 DOI: 10.1021/cr020619e] [Citation(s) in RCA: 233] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Julie A Kovacs
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, USA
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19
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Akermark B, Bjernemose J, Börje A, Chmielewski PJ, Paulsen H, Simonsen O, Stein PC, Toftlund H, Wolny JA. Strain-induced substitutional lability in a Ru(ii) complex of a hypodentate polypyridine ligand. Dalton Trans 2004:1215-20. [PMID: 15252663 DOI: 10.1039/b316093a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The ruthenium(II) complex of heptadentate N,N,N',N'-tetrakis(2-pyridylmethyl)-2,6-bis(aminomethyl)pyridine (tpap) was isolated as the hexafluorophosphate complex Ru(tpap)(PF6)2. The crystal structure has been determined for the triflate salt Ru(tpap)(CF3SO3)2.2H2O, which crystallizes in the monoclinic space group P2(1)/n. The structure was refined to a final R value of 0.0549 for 5894 observed reflections. The heptadentate ligand coordinates with six nitrogens, i.e. with two tertiary nitrogens and four pyridine nitrogens, one of the pyridines remaining un-coordinated. The resulting structure is significantly distorted from octahedral geometry with an equatorial Nsp3-Ru-Npyridine angle of 120 degrees. The consequence of the above steric strain is a labilization of the system and fluxional behaviour involving exchange between equatorially coordinated and non-coordinated pyridines has been observed by 1H NMR for Ru(tpap)(PF6)2 in d6-acetone solution. The activation parameters of DeltaG(not equal to 298) = 53 kJ mol(-1), DeltaH(not equal) = 56 +/- 1 kJ mol(-1) and DeltaS(not equal) = -10 +/- 3 J mol(-1) K(-1) were determined on the basis of NMR experiments. In addition electronic structure calculations applying density functional theory (DFT) have been performed in order to identify a transition state and to estimate the activation barrier. On the basis of NMR and DFT results the mechanism of isoexchange involving a hepta-coordinated intermediate has been proposed.
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Affiliation(s)
- Björn Akermark
- Stockholms Universitet, Organisk Kemi, Arrheniuslaboratoriet, 106 91 Stockholm, Sweden
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20
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Cowan DA, Cameron RA, Tsekoa TL. Comparative biology of mesophilic and thermophilic nitrile hydratases. ADVANCES IN APPLIED MICROBIOLOGY 2003; 52:123-58. [PMID: 12964242 DOI: 10.1016/s0065-2164(03)01005-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Don A Cowan
- Advanced Research Centre for Applied Microbiology, Department of Biotechnology, University of the Western Cape, Bellville 7535, Cape Town, South Africa
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21
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Tsujimura M, Odaka M, Nakayama H, Dohmae N, Koshino H, Asami T, Hoshino M, Takio K, Yoshida S, Maeda M, Endo I. A novel inhibitor for Fe-type nitrile hydratase: 2-cyano-2-propyl hydroperoxide. J Am Chem Soc 2003; 125:11532-8. [PMID: 13129355 DOI: 10.1021/ja035018z] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nitrile hydratase (NHase) is a non-heme iron or non-corrin cobalt enzyme having two post-translationally modified ligand residues, cysteine-sulfinic acid (alphaCys112-SO(2)H) and -sulfenic acid (alphaCys114-SOH). We studied the interaction between Fe-type NHase and isobutyronitrile (iso-BN) which had been reported as a competitive inhibitor with a K(i) value of 5 microM. From detailed kinetic studies of the inhibitory effect of iso-BN on Fe-type NHase, we found that authentic iso-BN was hydrated normally and that the impurity present in commercially available iso-BN inhibited NHase activity strongly. The inhibitory compound induced significant changes in the UV-vis absorption spectrum of NHase, suggesting its interaction with the iron center. This compound was purified by using reversed-phase HPLC and identified as 2-cyano-2-propyl hydroperoxide (Cpx) by (1)H and PFG-HMBC NMR spectroscopy. Upon addition of a stoichiometric amount of Cpx, NHase was irreversibly inactivated, probably by the oxidation of alphaCys114-SOH to Cys-SO(2)H. This result suggests that the -SOH structure of alphaCys114 is essential for the catalytic activity. The oxygen atom in Cys-SO(2)H is confirmed to come from the solvent H(2)O. The oxidized NHase was found to induce the UV-vis absorption spectral changes by addition of Cpx, suggesting that Cpx strongly interacted with iron(III) in the oxidized NHase to form a stable complex. Thus, Cpx functions as a novel irreversible inhibitor for NHase.
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Affiliation(s)
- Masanari Tsujimura
- Biomolecular Characterization Division, RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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22
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Grapperhaus CA, Li M, Patra AK, Poturovic S, Kozlowski PM, Zgierski MZ, Mashuta MS. Synthesis and characterization of N2S3X-Fe models of iron-containing nitrile hydratase. Inorg Chem 2003; 42:4382-8. [PMID: 12844310 DOI: 10.1021/ic026239t] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of iron complexes based on the pentadentate ligand 4,7-bis(2'-methyl-2'-mercaptopropyl)-1-thia-4,7-diazacyclononane), (bmmp-TASN)(2)(-), have been synthesized and characterized as models of iron-containing nitrile hydratase (NHase). The chloro derivative [(bmmp-TASN)Fe(III)Cl].0.5EtOH (1) contains a labile chloride which facilitates synthesis of related complexes via substitution reactions. Complex 1 is high-spin, g = 4.28. Addition of NEt(4)CN with 1 in CH(2)Cl(2) results in the cyanide ligated complex [(bmmp-TASN)Fe(III)CN] x 0.5EtOH (2), which shows a single intense nu(CN) band at 2083 cm(-)(1) in the IR region. Complex 2 is low-spin, g(1) = 2.31, g(2) = 2.16, and g(3) = 1.96. Under basic conditions complex 1 affords a mu-oxo bridged dimeric Fe(III) complex [(bmmp-TASN)Fe(III)](2)O (3), which shows an intense band at 799 cm(-)(1). Complex 3 was recrystallized from CH(2)Cl(2)/hexane solution in the triclinic space group P1, with a = 10.5486(15) A, b = 13.0612(19) A, c = 8.1852(12) A, alpha = 96.923(2) degrees, beta = 112.729(2) degrees, gamma = 81.048(2) degrees, and Z = 1. Density functional theory (DFT) calculations of the previously communicated iron-nitrosyl complex [(bmmp-TASN)Fe(III)(NO)][BPh(4)] (4) (Inorg. Chem. 2002, 41, 1039-1041) reveal that the HOMO region is dominated by Fe-S bonding. Complexes 1-4 display irreversible or quasi-reversible reductions in the cyclic voltammograms. All of the iron complexes and the zinc derivative, (bmmp-TASN)Zn (5), display an irreversible oxidation. Complex 5 was crystallized in the monoclinic space group P2(1)/n with a = 9.5759(6) A, b = 20.9790(13) A, c = 10.7113(7) A, beta = 91.283(1) degrees, and Z = 4.
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Affiliation(s)
- Craig A Grapperhaus
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, USA.
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23
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Shearer J, Fitch SB, Kaminsky W, Benedict J, Scarrow RC, Kovacs JA. How does cyanide inhibit superoxide reductase? Insight from synthetic FeIIIN4S model complexes. Proc Natl Acad Sci U S A 2003; 100:3671-6. [PMID: 12655068 PMCID: PMC152980 DOI: 10.1073/pnas.0637029100] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2002] [Indexed: 11/18/2022] Open
Abstract
Superoxide reductases (SORs) are nonheme iron-containing enzymes that reduce HO(2) to H(2)O(2). Exogenous substrates such as N(3)(-) and CN(-) have been shown to bind to the catalytic iron site of SOR, and cyanide acts as an inhibitor. To understand how these exogenous ligands alter the physical and reactivity properties of the SOR iron site, acetate-, azide-, and cyanide-ligated synthetic models of SOR have been prepared. The x-ray crystal structures of azide-ligated [Fe(III)(S(Me2)N(4)(tren))(N(3))](+) (3), dimeric cyanide-bridged ([Fe(III)(S(Me2)N(4)(tren))](2)-mu-CN)(3+) (5), and acetate-ligated [Fe(III)(S(Me2)N(4)(tren))(OAc)](+) (6) are described, in addition to x-ray absorption spectrum-derived and preliminary crystallographic structures of cyanide-ligated [Fe(III)(S(Me2)N(4)(tren))(CN)](+) (4). Cyanide coordination to our model (4) causes the redox potential to shift anodically by 470 mV relative to acetate-ligated 6 and 395 mV relative to azide-ligated 3. If cyanide coordination were to cause a similar shift in redox potential with SOR, then the reduction potential of the catalytically active Fe(3+) center would fall well below that of its biological reductants. These results suggest therefore that cyanide inhibits SOR activity by making the Fe(2+) state inaccessible and thus preventing the enzyme from turning over. Cyanide inhibits activity in the metalloenzyme superoxide dismutase via a similar mechanism. The reduced five-coordinate precursor to 3, 4, and 6 [Fe(II)(S(Me2)N(4)(tren))](+) (1) was previously shown by us to react with superoxide to afford H(2)O(2) via an [Fe(III)(S(Me2)N(4)(tren))(OOH)](+) intermediate. Cyanide and azide do not bind to 1 and do not prevent 1 from reducing superoxide.
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Affiliation(s)
- Jason Shearer
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700, USA
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Shearer J, Jackson HL, Schweitzer D, Rittenberg DK, Leavy TM, Kaminsky W, Scarrow RC, Kovacs JA. The first example of a nitrile hydratase model complex that reversibly binds nitriles. J Am Chem Soc 2002; 124:11417-28. [PMID: 12236756 PMCID: PMC4485622 DOI: 10.1021/ja012555f] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nitrile hydratase (NHase) is an iron-containing metalloenzyme that converts nitriles to amides. The mechanism by which this biochemical reaction occurs is unknown. One mechanism that has been proposed involves nucleophilic attack of an Fe-bound nitrile by water (or hydroxide). Reported herein is a five-coordinate model compound ([Fe(III)(S(2)(Me2)N(3)(Et,Pr))](+)) containing Fe(III) in an environment resembling that of NHase, which reversibly binds a variety of nitriles, alcohols, amines, and thiocyanate. XAS shows that five-coordinate [Fe(III)(S(2)(Me2)N(3)(Et,Pr))](+) reacts with both methanol and acetonitrile to afford a six-coordinate solvent-bound complex. Competitive binding studies demonstrate that MeCN preferentially binds over ROH, suggesting that nitriles would be capable of displacing the H(2)O coordinated to the iron site of NHase. Thermodynamic parameters were determined for acetonitrile (DeltaH = -6.2(+/-0.2) kcal/mol, DeltaS = -29.4(+/-0.8) eu), benzonitrile (-4.2(+/-0.6) kcal/mol, DeltaS = -18(+/-3) eu), and pyridine (DeltaH = -8(+/-1) kcal/mol, DeltaS = -41(+/-6) eu) binding to [Fe(III)(S(2)(Me2)N(3)(Et,Pr))](+) using variable-temperature electronic absorption spectroscopy. Ligand exchange kinetics were examined for acetonitrile, iso-propylnitrile, benzonitrile, and 4-tert-butylpyridine using (13)C NMR line-broadening analysis, at a variety of temperatures. Activation parameters for ligand exchange were determined to be DeltaH(+ +) = 7.1(+/-0.8) kcal/mol, DeltaS(+ +) = -10(+/-1) eu (acetonitrile), DeltaH(+ +) = 5.4(+/-0.6) kcal/mol, DeltaS(+ +) = -17(+/-2) eu (iso-propionitrile), DeltaH(+ +) = 4.9(+/-0.8) kcal/mol, DeltaS(+ +) = -20(+/-3) eu (benzonitrile), and DeltaH(+ +) = 4.7(+/-1.4) kcal/mol DeltaS(+ +) = -18(+/-2) eu (4-tert-butylpyridine). The thermodynamic parameters for pyridine binding to a related complex, [Fe(III)(S(2)(Me2)N(3)(Pr,Pr))](+) (DeltaH = -5.9(+/-0.8) kcal/mol, DeltaS = -24(+/-3) eu), are also reported, as well as kinetic parameters for 4-tert-butylpyridine exchange (DeltaH(+ +) = 3.1(+/-0.8) kcal/mol, DeltaS(+ +) = -25(+/-3) eu). These data show for the first time that, when it is contained in a ligand environment similar to that of NHase, Fe(III) is capable of forming a stable complex with nitriles. Also, the rates of ligand exchange demonstrate that low-spin Fe(III) in this ligand environment is more labile than expected. Furthermore, comparison of [Fe(III)(S(2)(Me2)N(3)(Et,Pr))](+) and [Fe(III)(S(2)(Me2)N(3)(Pr,Pr))](+) demonstrates how minor distortions induced by ligand constraints can dramatically alter the reactivity of a metal complex.
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Affiliation(s)
- Jason Shearer
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195
| | - Henry L. Jackson
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195
| | - Dirk Schweitzer
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195
| | - Durrell K. Rittenberg
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195
| | - Tanya M. Leavy
- Department of Chemistry, Haverford College, Haverford, PennsylVania 19041
| | | | - Robert C. Scarrow
- Department of Chemistry, Haverford College, Haverford, PennsylVania 19041
| | - Julie A. Kovacs
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195
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