1
|
Landrini M, Patel R, Tyrrell-Thrower J, Macchioni A, Hughes DL, Tensi L, Hrobárik P, Rocchigiani L. Exploring Ligand Effects on Structure, Bonding, and Photolytic Hydride Transfer of Cationic Gold(I) Bridging Hydride Complexes of Molybdocene and Tungstenocene. Inorg Chem 2024; 63:13525-13545. [PMID: 38989543 DOI: 10.1021/acs.inorgchem.4c01655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
A diverse family of heterobimetallic bridging hydride adducts of the type [LAu(μ-H)2MCp2][X] (L = 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene, IPr; 1,3-bis(1-adamantyl)imidazole-2-ylidene, IAd; 1,3-bis(2,6-di-iso-propylphenyl)-5,5-dimethyl-4,6-diketopyrimidinyl-2-ylidene, DippDAC; triphenylphosphine, PPh3; 2-di-tert-butylphosphino-2',4',6'-triisopropylbiphenyl, tBuXPhos; X = SbF6-, BF4- or TfO-) was synthesized by reacting group VI metallocene dihydrides Cp2MH2 (Cp = cyclopentadienyl anion; M = Mo, W) with cationic gold(I) complexes [LAu(NCMe)][X]. Trimetallic [L'Au2(μ-H)2WCp2][X]2 and tetrametallic [L'Au2{(μ-H)2WCp2}2] [X]2 complexes (L' = rac-2,2'-bis(diphenylphosphino)-1,1'-binaphthalene or bis(diphenylphosphinomethane)) were obtained by reacting digold [L'{Au(NCMe)}2][X]2 with Cp2WH2 in a 1:1 and a 1:2 stoichiometry. Accessing such a broad structural diversity allowed us to pinpoint roles played by the ancillary ligands and group VI metals on the bonding properties of this family of bridging hydrides. In particular, a clear effect of the ligand on the interaction energy and electronic structure was observed, with important implications on photolytic reactivity. UV or visible light irradiation, indeed, leads to the selective cleavage of the heterobimetallic Au(μ-H)2M arrangement and formation of molecular gold hydrides. The photolysis was found to be chromoselective (wavelength-dependent), which can be ascribed to different charge redistributions upon excitation to the first (Kasha's reactivity) and higher (anti-Kasha's reactivity) excited states.
Collapse
Affiliation(s)
- Martina Landrini
- Department of Chemistry, Biology and Biotechnology, University of Perugia and CIRCC, Via Elce di Sotto 8, 06123 Perugia, Italy
| | - Rohan Patel
- School of Chemistry, University of East Anglia, Norwich Research Park, NR4 7TJ Norwich, U.K
| | - Joshua Tyrrell-Thrower
- School of Chemistry, University of East Anglia, Norwich Research Park, NR4 7TJ Norwich, U.K
| | - Alceo Macchioni
- Department of Chemistry, Biology and Biotechnology, University of Perugia and CIRCC, Via Elce di Sotto 8, 06123 Perugia, Italy
| | - David L Hughes
- School of Chemistry, University of East Anglia, Norwich Research Park, NR4 7TJ Norwich, U.K
| | - Leonardo Tensi
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo 1, 06123 Perugia, Italy
| | - Peter Hrobárik
- Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, SK-84215 Bratislava, Slovakia
| | - Luca Rocchigiani
- Department of Chemistry, Biology and Biotechnology, University of Perugia and CIRCC, Via Elce di Sotto 8, 06123 Perugia, Italy
- School of Chemistry, University of East Anglia, Norwich Research Park, NR4 7TJ Norwich, U.K
| |
Collapse
|
2
|
Nemykin VN, Sabin JR, Kail BW, Upadhyay A, Hendrich MP, Basu P. Influence of the ligand-field on EPR parameters of cis- and trans-isomers in Mo V systems relevant to molybdenum enzymes: Experimental and density functional theory study. J Inorg Biochem 2023; 245:112228. [PMID: 37149488 PMCID: PMC10330323 DOI: 10.1016/j.jinorgbio.2023.112228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 04/12/2023] [Accepted: 04/12/2023] [Indexed: 05/08/2023]
Abstract
The electron paramagnetic resonance (EPR) investigation of mononuclear cis- and trans-(L1O)MoOCl2 complexes [L1OH = bis(3,5-dimethylpyrazolyl)-3-tert-butyl-2-hydroxy-5-methylphenyl)methane] reveals a significant difference in their spin Hamiltonian parameters which reflect different equatorial and axial ligand fields created by the heteroscorpionate donor atoms. Density functional theory (DFT) was used to calculate the values of principal components and relative orientations of the g and A tensors, and the molecular framework in four pairs of isomeric mononuclear oxo‑molybdenum(V) complexes (cis- and trans-(L1O)MoOCl2, cis,cis- and cis,trans-(L-N2S2)MoOCl [L-N2S2H2 = N,N'-dimethyl-N,N'-bis(mercaptophenyl)ethylenediamine], cis,cis- and cis,trans-(L-N2S2)MoO(SCN), and cis- and trans-[(dt)2MoO(OMe)]2- [dtH2 = 2,3-dimercapto-2-butene]). Scalar relativistic DFT calculations were conducted using three different exchange-correlation functionals. It was found that the use of hybrid exchange-correlation functional with 25% of the Hartree-Fock exchange leads to the best quantitative agreement between theory and experiment. A simplified ligand-field approach was used to analyze the influence of the ligand fields in all cis- and trans-isomers on energies and contributions of molybdenum d-orbital manifold to g and A tensors and relative orientations. Specifically, contributions that originated from the spin-orbit coupling of the dxz, dyz, and dx2-y2 orbitals into the ground state have been discussed. The new findings are discussed in the context of the experimental data of mononuclear molybdoenzyme, DMSO reductase.
Collapse
Affiliation(s)
- Victor N Nemykin
- Department of Chemistry, University of Tennessee - Knoxville, Knoxville, TN 37996, USA; Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN 55812, USA.
| | - Jared R Sabin
- Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN 55812, USA
| | - Brian W Kail
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15216, USA
| | - Anup Upadhyay
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Michael P Hendrich
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15216, USA; Department of Chemistry and Chemical Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA.
| |
Collapse
|
3
|
Gómez-Piñeiro RJ, Drosou M, Bertaina S, Decroos C, Simaan AJ, Pantazis DA, Orio M. Decoding the Ambiguous Electron Paramagnetic Resonance Signals in the Lytic Polysaccharide Monooxygenase from Photorhabdus luminescens. Inorg Chem 2022; 61:8022-8035. [PMID: 35549254 PMCID: PMC9131454 DOI: 10.1021/acs.inorgchem.2c00766] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding the structure and function of lytic polysaccharide monooxygenases (LPMOs), copper enzymes that degrade recalcitrant polysaccharides, requires the reliable atomistic interpretation of electron paramagnetic resonance (EPR) data on the Cu(II) active site. Among various LPMO families, the chitin-active PlAA10 shows an intriguing phenomenology with distinct EPR signals, a major rhombic and a minor axial signal. Here, we combine experimental and computational investigations to uncover the structural identity of these signals. X-band EPR spectra recorded at different pH values demonstrate pH-dependent population inversion: the major rhombic signal at pH 6.5 becomes minor at pH 8.5, where the axial signal dominates. This suggests that a protonation change is involved in the interconversion. Precise structural interpretations are pursued with quantum chemical calculations. Given that accurate calculations of Cu g-tensors remain challenging for quantum chemistry, we first address this problem via a thorough calibration study. This enables us to define a density functional that achieves accurate and reliable prediction of g-tensors, giving confidence in our evaluation of PlAA10 LPMO models. Large models were considered that include all parts of the protein matrix surrounding the Cu site, along with the characteristic second-sphere features of PlAA10. The results uniquely identify the rhombic signal with a five-coordinate Cu ion bearing two water molecules in addition to three N-donor ligands. The axial signal is attributed to a four-coordinate Cu ion where only one of the waters remains bound, as hydroxy. Alternatives that involve decoordination of the histidine brace amino group are unlikely based on energetics and spectroscopy. These results provide a reliable spectroscopy-consistent view on the plasticity of the resting state in PlAA10 LPMO as a foundation for further elucidating structure-property relationships and the formation of catalytically competent species. Our strategy is generally applicable to the study of EPR parameters of mononuclear copper-containing metalloenzymes.
Collapse
Affiliation(s)
| | - Maria Drosou
- Inorganic Chemistry Laboratory, National and Kapodistrian University of Athens, Panepistimiopolis, Zografou 15771, Greece
| | - Sylvain Bertaina
- Aix-Marseille Université, CNRS, IM2NP UMR 7334, Marseille 13397, France
| | - Christophe Decroos
- Aix Marseille Université, CNRS, Centrale Marseille, iSm2, Marseille 13397, France
| | - A Jalila Simaan
- Aix Marseille Université, CNRS, Centrale Marseille, iSm2, Marseille 13397, France
| | - Dimitrios A Pantazis
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Maylis Orio
- Aix Marseille Université, CNRS, Centrale Marseille, iSm2, Marseille 13397, France
| |
Collapse
|
4
|
EPR Spectroscopy of Cu(II) Complexes: Prediction of g-Tensors Using Double-Hybrid Density Functional Theory. MAGNETOCHEMISTRY 2022. [DOI: 10.3390/magnetochemistry8040036] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Computational electron paramagnetic resonance (EPR) spectroscopy is an important field of applied quantum chemistry that contributes greatly to connecting spectroscopic observations with the fundamental description of electronic structure for open-shell molecules. However, not all EPR parameters can be predicted accurately and reliably for all chemical systems. Among transition metal ions, Cu(II) centers in inorganic chemistry and biology, and their associated EPR properties such as hyperfine coupling and g-tensors, pose exceptional difficulties for all levels of quantum chemistry. In the present work, we approach the problem of Cu(II) g-tensor calculations using double-hybrid density functional theory (DHDFT). Using a reference set of 18 structurally and spectroscopically characterized Cu(II) complexes, we evaluate a wide range of modern double-hybrid density functionals (DHDFs) that have not been applied previously to this problem. Our results suggest that the current generation of DHDFs consistently and systematically outperform other computational approaches. The B2GP-PLYP and PBE0-DH functionals are singled out as the best DHDFs on average for the prediction of Cu(II) g-tensors. The performance of the different functionals is discussed and suggestions are made for practical applications and future methodological developments.
Collapse
|
5
|
Theibich YA, Sauer SP, Leggio LL, Hedegård ED. Estimating the accuracy of calculated electron paramagnetic resonance hyperfine couplings for a lytic polysaccharide monooxygenase. Comput Struct Biotechnol J 2020; 19:555-567. [PMID: 33510861 PMCID: PMC7807142 DOI: 10.1016/j.csbj.2020.12.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/11/2020] [Accepted: 12/13/2020] [Indexed: 11/07/2022] Open
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are enzymes that bind polysaccharides followed by an (oxidative) disruption of the polysaccharide surface, thereby boosting depolymerization. The binding process between the LPMO catalytic domain and polysaccharide is key to the mechanism and establishing structure-function relationships for this binding is therefore crucial. The hyperfine coupling constants (HFCs) from EPR spectroscopy have proven useful for this purpose. Unfortunately, EPR does not provide direct structural data and therefore the experimental EPR parameters have to be supported with parameters calculated with density functional theory. Yet, calculated HFCs are extremely sensitive to the employed computational setup. Using the LPMO Ls(AA9)A catalytic domain, we here quantify the importance of several choices in the computational setup, ranging from the use of specialized basis, the underlying structures, and the employed exchange-correlation functional. We show that specialized basis sets are an absolute necessity, and also that care has to be taken in the optimization of the underlying structure: only by allowing large parts of the protein around the active site to structurally relax could we obtain results that uniformly reproduced experimental trends. We compare our results to previously published X-ray structures and experimental HFCs for Ls(AA9)A as well as to recent experimental/theoretical results for another (AA10) family of LPMOs.
Collapse
Affiliation(s)
- Yusuf A. Theibich
- Department of Chemistry, University of University, Copenhagen, Denmark
| | | | - Leila Lo Leggio
- Department of Chemistry, University of University, Copenhagen, Denmark
| | - Erik D. Hedegård
- Division of Theoretical Chemistry, Lund University, Chemical Centre, P. O. Box 124, SE-221 00 Lund, Sweden
| |
Collapse
|
6
|
Gohr S, Hrobárik P, Kaupp M. Four-Component Relativistic Density Functional Calculations of EPR Parameters for Model Complexes of Tungstoenzymes. J Phys Chem A 2017; 121:9106-9117. [DOI: 10.1021/acs.jpca.7b08768] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sebastian Gohr
- Institut
für Chemie, Theoretische Chemie/Quantenchemie, Technische Universität Berlin, Sekr. C7, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Peter Hrobárik
- Institut
für Chemie, Theoretische Chemie/Quantenchemie, Technische Universität Berlin, Sekr. C7, Straße des 17. Juni 135, 10623 Berlin, Germany
- Department
of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina CH-2, Ilkovičova 6, SK-84215 Bratislava, Slovakia
| | - Martin Kaupp
- Institut
für Chemie, Theoretische Chemie/Quantenchemie, Technische Universität Berlin, Sekr. C7, Straße des 17. Juni 135, 10623 Berlin, Germany
| |
Collapse
|
7
|
Burcher B, Sanders KJ, Benda L, Pintacuda G, Jeanneau E, Danopoulos AA, Braunstein P, Olivier-Bourbigou H, Breuil PAR. A Straightforward Access to Stable, 16 Valence-electron Phosphine-Stabilized Fe 0 Olefin Complexes and their Reactivity. Organometallics 2017; 36:605-613. [PMID: 31031510 DOI: 10.1021/acs.organomet.6b00803] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The use of the dialkene divinyltetramethyldisiloxane (dvtms) allows easy access to the reactive 16 valence-electron complexes [Fe0(L-L)(dvtms)], (L-L) = dppe (1,2-bis(diphenylphosphino)ethane), (1), dppp (1,2-bis(diisopropylphosphino)propane), (2), pyNMeP(iPr)2 (N-(diisopropylphosphino)-N-methylpyridin-2-amine), (4), dipe (1,2-bis(diisopropylphosphino)ethane), (5), and [Fe0(L)2(dvtms)], L = PMe3, (3), by a mild reductive route using AlEt2(OEt) as reducing agent. In contrast, by the same methodology, the 18 valence-electron complexes [Fe0(L-L)2(ethylene)], (L-L) = dppm (1,2-bis(diphenylphosphino)methane), 6, (L-L) = dppa (1,2-bis(diphenylphosphino)amine) 7 or (L-L)=dppe, 8, were obtained, which do not contain dvtms. In addition, a combined DFT and solid-state paramagnetic NMR methodology is introduced for the structure determination of 5. A comparative study of the reactivity of 1,2,4-6 and 8 with 3-hexyne highlights emerging mechanistic implications for C-C coupling reactions using these complexes as catalysts.
Collapse
Affiliation(s)
- Benjamin Burcher
- IFP Energies nouvelles, Rond-point de l'échangeur de Solaize, BP 3, 69360 Solaize, France
| | - Kevin J Sanders
- Institut des Sciences Analytiques, UMR 5280 CNRS, Université de Lyon, École Normale Supérieure de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Ladislav Benda
- Institut des Sciences Analytiques, UMR 5280 CNRS, Université de Lyon, École Normale Supérieure de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Guido Pintacuda
- Institut des Sciences Analytiques, UMR 5280 CNRS, Université de Lyon, École Normale Supérieure de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
| | - Erwann Jeanneau
- Centre de Diffractométrie Henri Longchambon, Site CLEA - Bât. ISA, 3ème étage, 5 rue de La Doua, 69100 Villeurbanne, France
| | - Andreas A Danopoulos
- Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, 4 rue Blaise Pascal, CS90032, 67081 Strasbourg, France
| | - Pierre Braunstein
- Université de Strasbourg, CNRS, CHIMIE UMR 7177, Laboratoire de Chimie de Coordination, 4 rue Blaise Pascal, CS90032, 67081 Strasbourg, France
| | | | - Pierre-Alain R Breuil
- IFP Energies nouvelles, Rond-point de l'échangeur de Solaize, BP 3, 69360 Solaize, France
| |
Collapse
|
8
|
Young CG. Chemical systems modeling the d1 Mo(V) states of molybdenum enzymes. J Inorg Biochem 2016; 162:238-252. [PMID: 27432259 DOI: 10.1016/j.jinorgbio.2016.06.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/14/2016] [Accepted: 06/03/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Charles G Young
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia.
| |
Collapse
|
9
|
Affiliation(s)
- Charles G. Young
- Department of Chemistry and PhysicsLa Trobe Institute for Molecular ScienceLa Trobe University3086MelbourneVictoriaAustralia
| |
Collapse
|
10
|
Gohr S, Hrobárik P, Repiský M, Komorovský S, Ruud K, Kaupp M. Four-Component Relativistic Density Functional Theory Calculations of EPR g- and Hyperfine-Coupling Tensors Using Hybrid Functionals: Validation on Transition-Metal Complexes with Large Tensor Anisotropies and Higher-Order Spin–Orbit Effects. J Phys Chem A 2015; 119:12892-905. [DOI: 10.1021/acs.jpca.5b10996] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sebastian Gohr
- Institut für Chemie, Theoretische
Chemie/Quantenchemie, Technische Universität Berlin, Sekr. C7, Straße des 17. Juni
135, 10623 Berlin, Germany
| | - Peter Hrobárik
- Institut für Chemie, Theoretische
Chemie/Quantenchemie, Technische Universität Berlin, Sekr. C7, Straße des 17. Juni
135, 10623 Berlin, Germany
| | - Michal Repiský
- Department of Chemistry, Centre for Theoretical
and Computational Chemistry (CTCC), UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Stanislav Komorovský
- Department of Chemistry, Centre for Theoretical
and Computational Chemistry (CTCC), UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Kenneth Ruud
- Department of Chemistry, Centre for Theoretical
and Computational Chemistry (CTCC), UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Martin Kaupp
- Institut für Chemie, Theoretische
Chemie/Quantenchemie, Technische Universität Berlin, Sekr. C7, Straße des 17. Juni
135, 10623 Berlin, Germany
| |
Collapse
|
11
|
Doonan CJ, Gourlay C, Nielsen DJ, Ng VWL, Smith PD, Evans DJ, George GN, White JM, Young CG. d(1) Oxosulfido-Mo(V) Compounds: First Isolation and Unambiguous Characterization of an Extended Series. Inorg Chem 2015; 54:6386-96. [PMID: 26046577 DOI: 10.1021/acs.inorgchem.5b00708] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reaction of Tp(iPr)Mo(VI)OS(OAr) with cobaltocene in toluene results in the precipitation of brown, microcrystalline oxosulfido-Mo(V) compounds, [CoCp2][Tp(iPr)Mo(V)OS(OAr)] (Cp(-) = η(5)-C5H5(-), Tp(iPr)(-) = hydrotris(3-isopropylpyrazol-1-yl)borate, OAr(-) = phenolate or 2-(s)Bu, 2-(t)Bu, 3-(t)Bu, 4-(s)Bu, 4-Ph, 3,5-(s)Bu2, 2-CO2Me, 2-CO2Et or 2-CO2Ph derivative thereof). The compounds are air- and water-sensitive and display ν(Mo═O) and ν(Mo[Formula: see text]S) IR absorption bands at ca. 890 and 435 cm(-1), respectively, 20-40 cm(-1) lower in energy than the corresponding bands in Tp(iPr)MoOS(OAr). They are electrochemically active and exhibit three reversible cyclovoltammetric waves (E(Mo(VI)/Mo(V)) = -0.40 to -0.66 V, E([CoCp2](+)/CoCp2) = -0.94 V and E(CoCp2/[CoCp2](-)) = -1.88 V vs SCE). Structural characterization of [CoCp2][Tp(iPr)MoOS(OC6H4CO2Et-2)]·2CH2Cl2 revealed a distorted octahedral Mo(V) anion with Mo═O and Mo[Formula: see text]S distances of 1.761(5) and 2.215(2) Å, respectively, longer than corresponding distances in related Tp(iPr)MoOS(OAr) compounds. The observation of strong S(1s) → (S(3p) + Mo(4d)) S K-preedge transitions indicative of a d(1) sulfido-Mo(V) moiety and the presence of short Mo═O (ca. 1.72 Å) and Mo[Formula: see text]S (ca. 2.25 Å) backscattering contributions in the Mo K-edge EXAFS further support the oxosulfido-Mo(V) formulation. The compounds are EPR-active, exhibiting highly anisotropic (Δg 0.124-0.150), rhombic, frozen-glass spectra with g1 close to the value observed for the free electron (ge = 2.0023). Spectroscopic studies are consistent with the presence of a highly covalent Mo[Formula: see text]S π* singly occupied molecular orbital. The compounds are highly reactive, with reactions localized at the terminal sulfido ligand. For example, the compounds react with cyanide and PPh3 to produce thiocyanate and SPPh3, respectively, and various (depending on solvent) oxo-Mo(V) species. Reactions with copper reagents also generally lead to desulfurization and the formation of oxo-Mo(V) or -Mo(IV) complexes.
Collapse
Affiliation(s)
| | | | | | | | | | | | - Graham N George
- §Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | | | - Charles G Young
- ¶Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia
| |
Collapse
|
12
|
Wang FM. Synthesis, structure, and catalytic property of a mononuclear dioxomolybdenum(VI) complex containing MoON core. RUSS J COORD CHEM+ 2014. [DOI: 10.1134/s1070328414040101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
13
|
Hedegård ED, Kongsted J, Sauer SPA. Validating and Analyzing EPR Hyperfine Coupling Constants with Density Functional Theory. J Chem Theory Comput 2013; 9:2380-8. [PMID: 26583728 DOI: 10.1021/ct400171c] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Erik D Hedegård
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark
| | - Jacob Kongsted
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark
| | | |
Collapse
|
14
|
Eaton SS, Eaton GR. The world as viewed by and with unpaired electrons. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 223:151-63. [PMID: 22975244 PMCID: PMC3496796 DOI: 10.1016/j.jmr.2012.07.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 07/26/2012] [Accepted: 07/27/2012] [Indexed: 06/01/2023]
Abstract
Recent advances in electron paramagnetic resonance (EPR) include capabilities for applications to areas as diverse as archeology, beer shelf life, biological structure, dosimetry, in vivo imaging, molecular magnets, and quantum computing. Enabling technologies include multifrequency continuous wave, pulsed, and rapid scan EPR. Interpretation is enhanced by increasingly powerful computational models.
Collapse
Affiliation(s)
- Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
| | | |
Collapse
|
15
|
Biaso F, Burlat B, Guigliarelli B. DFT Investigation of the Molybdenum Cofactor in Periplasmic Nitrate Reductases: Structure of the Mo(V) EPR-Active Species. Inorg Chem 2012; 51:3409-19. [DOI: 10.1021/ic201533p] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Frédéric Biaso
- Unité de Bioénergétique
et Ingénierie des Protéines, UMR 7281, Centre National
de la Recherche Scientifique, Institut de Microbiologie de la Méditerranée,
and Aix-Marseille University, 31 Chemin
Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Bénédicte Burlat
- Unité de Bioénergétique
et Ingénierie des Protéines, UMR 7281, Centre National
de la Recherche Scientifique, Institut de Microbiologie de la Méditerranée,
and Aix-Marseille University, 31 Chemin
Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Bruno Guigliarelli
- Unité de Bioénergétique
et Ingénierie des Protéines, UMR 7281, Centre National
de la Recherche Scientifique, Institut de Microbiologie de la Méditerranée,
and Aix-Marseille University, 31 Chemin
Joseph Aiguier, 13402 Marseille Cedex 20, France
| |
Collapse
|
16
|
Rajapakshe A, Astashkin AV, Klein EL, Reichmann D, Mendel RR, Bittner F, Enemark JH. Structural studies of the molybdenum center of mitochondrial amidoxime reducing component (mARC) by pulsed EPR spectroscopy and 17O-labeling. Biochemistry 2011; 50:8813-22. [PMID: 21916412 DOI: 10.1021/bi2005762] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Mitochondrial amidoxime reducing components (mARC-1 and mARC-2) represent a novel group of Mo-containing enzymes in eukaryotes. These proteins form the catalytic part of a three-component enzyme complex known to be responsible for the reductive activation of several N-hydroxylated prodrugs. No X-ray crystal structures are available for these enzymes as yet. A previous biochemical investigation [Wahl, B., et al. (2010) J. Biol. Chem., 285, 37847-37859 ] has revealed that two of the Mo coordination positions are occupied by sulfur atoms from a pyranopterindithiolate (molybdopterin, MPT) cofactor. In this work, we have used continuous wave and pulsed electron paramagnetic resonance (EPR) spectroscopy and density functional theoretical (DFT) calculations to determine the nature of remaining ligands in the Mo(V) state of the active site of mARC-2. Experiments with samples in D(2)O have identified the exchangeable equatorial ligand as a hydroxyl group. Experiments on samples in H(2)(17)O-enriched buffer have shown the presence of a slowly exchangeable axial oxo ligand. Comparison of the experimental (1)H and (17)O hyperfine interactions with those calculated using DFT has shown that the remaining nonexchangeable equatorial ligand is, most likely, protein-derived and that the possibility of an equatorial oxo ligand can be excluded.
Collapse
Affiliation(s)
- Asha Rajapakshe
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, USA
| | | | | | | | | | | | | |
Collapse
|
17
|
Assessment of higher-order spin–orbit effects on electronic g-tensors of d 1 transition-metal complexes by relativistic two- and four-component methods. Theor Chem Acc 2011. [DOI: 10.1007/s00214-011-0951-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
18
|
Egorochkin AN, Kuznetsova OV, Khamaletdinova NM, Domratcheva-Lvova LG. EPR parameters of radical ions and polarizability effect. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2011; 49:175-183. [PMID: 21391241 DOI: 10.1002/mrc.2727] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 10/15/2010] [Accepted: 12/17/2010] [Indexed: 05/30/2023]
Abstract
The literature data on substituent influence on the g factors, hyperfine coupling (hfc) constants (a) of the EPR signals and the spin densities (ρ) have been analyzed for 25 series of the organic radical cations and radical anions as well as of the transition metal complexes. The g, a, and ρ values were first established to depend not only on the inductive and resonance effects but also on the polarizability of substituents which can be characterized by the σ(α) constants. The polarizability effect is caused by the partial charge on the radical center. This effect consists in an electrostatic attraction between the charge and the dipole moments induced by this charge in the substituents. The polarizability contribution ranges up to 92%.
Collapse
Affiliation(s)
- Alexey N Egorochkin
- G A Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Nizhny Novgorod, Russia
| | | | | | | |
Collapse
|
19
|
Hernandez-Marin E, Seth M, Ziegler T. Density Functional Theory Study of the Electron Paramagnetic Resonance Parameters and the Magnetic Circular Dichroism Spectrum for Model Compounds of Dimethyl Sulfoxide Reductase. Inorg Chem 2010; 49:1566-76. [DOI: 10.1021/ic901888q] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Elizabeth Hernandez-Marin
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Michael Seth
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Tom Ziegler
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| |
Collapse
|
20
|
Hadt RG, Nemykin VN, Olsen JG, Basu P. Comparative calculation of EPR spectral parameters in [Mo(V)OX4]-, [Mo(V)OX5]2-, and [Mo(V)OX4(H2O)]- complexes. Phys Chem Chem Phys 2009; 11:10377-84. [PMID: 19890522 PMCID: PMC2879133 DOI: 10.1039/b905554a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The EPR spectral parameters, i.e. g-tensors and molybdenum hyperfine couplings, for several d(1) systems of the general formula [Mo(V)EX(4)](n-), [Mo(V)OX(5)](2-), and [Mo(V)OX(4)(H(2)O)](-) (E = O, N; X = F, Cl, Br; n = 1 or 2) were calculated using Density Functional Theory. The influence of basis sets, their contraction scheme, the type of exchange-correlation functional, the amount of Hartree-Fock exchange, molecular geometry, and relativistic effects on the calculated EPR spectra parameters have been discussed. The g-tensors and molybdenum hyperfine coupling parameters were calculated using a relativistic Hamiltonian coupled with several LDA, GGA, and 'hybrid' exchange-correlation functionals and uncontracted full-electron DGauss DZVP basis sets. The calculated EPR parameters are found to be sensitive to the Mo=E distance and E=Mo-Cl angle, and thus the choice of starting molecular geometry should be considered as an important factor in predicting the g-tensors and hyperfine coupling constants in oxo-molybdenum compounds. In the present case, the GGA exchange-correlation functionals provide a better agreement between the theory and the experiment.
Collapse
Affiliation(s)
- Ryan G. Hadt
- Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN 55812, USA.
| | - Victor N. Nemykin
- Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN 55812, USA.
| | - Joseph G. Olsen
- Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN 55812, USA.
| | - Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, USA.
| |
Collapse
|
21
|
Ryde U, Schulzke C, Starke K. Which functional groups of the molybdopterin ligand should be considered when modeling the active sites of the molybdenum and tungsten cofactors? A density functional theory study. J Biol Inorg Chem 2009; 14:1053-64. [PMID: 19479286 PMCID: PMC3085732 DOI: 10.1007/s00775-009-0548-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 05/01/2009] [Indexed: 11/29/2022]
Abstract
A density functional theory study of the influence of the various functional groups of the molybdopterin ligand on electronic and geometric properties of active-site models for the molybdenum and tungsten cofactors has been undertaken. We used analogous molybdenum and tungsten complexes with increasingly accurate representation of the molybdopterin ligands and compared bond lengths, angles, charge distribution, composition of the binding orbitals, as well as the redox potentials in relation to each other. On the basis of our findings, we suggest using ligand systems including the pyrane and the pyrazine rings, besides the dithiolene function, to obtain sufficiently reliable computational, but also synthetic, models for the molybdenum and tungsten cofactors, whereas the second ring of the pterin might be neglected for efficiency reasons.
Collapse
Affiliation(s)
- Ulf Ryde
- Department of Theoretical Chemistry, Chemical Center, Lund University, 124, 221 00 Lund, Sweden
| | - Carola Schulzke
- Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstr. 4, 37077 Göttingen, Germany
| | - Kerstin Starke
- Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstr. 4, 37077 Göttingen, Germany
- Department of Chemical Physics, Chemical Center, Lund University, 124, 221 00 Lund, Sweden
| |
Collapse
|
22
|
A multiconfigurational perturbation theory study of the electronic structure and EPR g values of an oxomolybdenum enzyme model complex. Theor Chem Acc 2009. [DOI: 10.1007/s00214-009-0605-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
23
|
Hrobárik P, Malkina OL, Malkin VG, Kaupp M. Relativistic two-component calculations of electronic g-tensor for oxo-molybdenum(V) and oxo-tungsten(V) complexes: The important role of higher-order spin-orbit contributions. Chem Phys 2009. [DOI: 10.1016/j.chemphys.2008.10.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
24
|
Hernandez-Marin E, Ziegler T. Theoretical Study of the Oxidation Reaction and Electron Spin Resonance Parameters Involving Sulfite Oxidase. Inorg Chem 2009; 48:1323-33. [DOI: 10.1021/ic801158t] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Elizabeth Hernandez-Marin
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4
| | - Tom Ziegler
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4
| |
Collapse
|
25
|
Rinkevicius Z, de Almeida KJ, Oprea CI, Vahtras O, Ågren H, Ruud K. Degenerate Perturbation Theory for Electronic g Tensors: Leading-Order Relativistic Effects. J Chem Theory Comput 2008; 4:1810-28. [DOI: 10.1021/ct800053f] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Zilvinas Rinkevicius
- Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Katia Julia de Almeida
- Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Cornel I. Oprea
- Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Olav Vahtras
- Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Hans Ågren
- Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, SE-10691 Stockholm, Sweden
| | - Kenneth Ruud
- Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway
| |
Collapse
|