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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.
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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.
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2
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Perchlorate reduction catalyzed by dioxidomolybdenum(VI) complexes: Effect of ligand substituents. J Catal 2022. [DOI: 10.1016/j.jcat.2022.11.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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3
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Ćorović MZ, Wiedemaier F, Belaj F, Mösch-Zanetti NC. Replacement of Molybdenum by Tungsten in a Biomimetic Complex Leads to an Increase in Oxygen Atom Transfer Catalytic Activity. Inorg Chem 2022; 61:12415-12424. [PMID: 35894844 PMCID: PMC9367641 DOI: 10.1021/acs.inorgchem.2c01868] [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: 11/28/2022]
Abstract
Upon replacement of molybdenum by tungsten in DMSO reductase isolated from the Rhodobacteraceae family, the derived enzyme catalyzes DMSO reduction faster. To better understand this behavior, we synthesized two tungsten(VI) dioxido complexes [WVIO2L2] with pyridine- (PyS) and pyrimidine-2-thiolate (PymS) ligands, isostructural to analogous molybdenum complexes we reported recently. Higher oxygen atom transfer (OAT) catalytic activity was observed with [WO2(PyS)2] compared to the Mo species, independent of whether PMe3 or PPh3 was used as the oxygen acceptor. [WVIO2L2] complexes undergo reduction with an excess of PMe3, yielding the tungsten(IV) oxido species [WOL2(PMe3)2], while with PPh3, no reactions are observed. Although OAT reactions from DMSO to phosphines are known for tungsten complexes, [WOL2(PMe3)2] are the first fully characterized phosphine-stabilized intermediates. By following the reaction of these reduced species with excess DMSO via UV-vis spectroscopy, we observed that tungsten compounds directly react to WVIO2 complexes while the Mo analogues first form μ-oxo Mo(V) dimers [Mo2O3L4]. Density functional theory calculations confirm that the oxygen atom abstraction from WVIO2 is an endergonic process contrasting the respective reaction with molybdenum. Here, we suggest that depending on the sacrificial oxygen acceptor, the tungsten complex may participate in catalysis either via a redox reaction or as an electrophile.
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Affiliation(s)
- Miljan Z Ćorović
- Institute of Chemistry, Inorganic Chemistry, University of Graz, 8010 Graz, Austria
| | - Fabian Wiedemaier
- Institute of Chemistry, Inorganic Chemistry, University of Graz, 8010 Graz, Austria
| | - Ferdinand Belaj
- Institute of Chemistry, Inorganic Chemistry, University of Graz, 8010 Graz, Austria
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4
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Erickson AN, Gianino J, Markovitz SJ, Brown SN. Amphiphilicity in Oxygen Atom Transfer Reactions of Oxobis(iminoxolene)osmium Complexes. Inorg Chem 2021; 60:4004-4014. [PMID: 33657323 DOI: 10.1021/acs.inorgchem.1c00068] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Oxobis(iminoxolene)osmium(VI) compounds (Rap)2OsO (Rap = 2-(4-RC6H4N)-4,6-tBu2C6H2O) are readily deoxygenated by phosphines and phosphites to give five-coordinate (Rap)2Os(PR'3) or six-coordinate (Rap)2Os(PR'3)2. Structural data indicate that this net two-electron reduction is accompanied by apparent oxidation of the iminoxolene ligands due to their greater ability to engage in π donation to the reduced deoxy form of the osmium complex. In (Rap)2Os(PR'3)2, the HOMO is a ligand-based combination of the iminoxolene redox-active orbitals, while the LUMO is a highly covalent metal-iminoxolene π* orbital. In the trans isomer, the HOMO is required to be ligand-localized by symmetry, while in the cis isomer, the ligands adopt a conformation that minimizes metal-ligand π* interactions in the HOMO. Kinetic studies indicate that the deoxygenations involve the rate-determining attack of the phosphorus(III) reagent on the five-coordinate oxo complexes. Varying the substituents of the aryl groups on the iminoxolene ligands or on the triarylphosphines has little effect on the rate of oxygen atom transfer, with the best correlation shown between oxygen atom transfer rates and the HOMO-LUMO gap of the oxo complexes. This suggests that the osmium oxo group shows a balance between electrophilic and nucleophilic character in its oxygen atom transfer reactions with phosphorus(III) reagents.
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Affiliation(s)
- Alexander N Erickson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
| | - Jacqueline Gianino
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
| | - Sean J Markovitz
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
| | - Seth N Brown
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
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5
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Ehweiner MA, Wiedemaier F, Belaj F, Mösch-Zanetti NC. Oxygen Atom Transfer Reactivity of Molybdenum(VI) Complexes Employing Pyrimidine- and Pyridine-2-thiolate Ligands. Inorg Chem 2020; 59:14577-14593. [PMID: 32951421 DOI: 10.1021/acs.inorgchem.0c02412] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Four dioxidomolybdenum(VI) complexes of the general structure [MoO2L2] employing the S,N-bidentate ligands pyrimidine-2-thiolate (PymS, 1), pyridine-2-thiolate (PyS, 2), 4-methylpyridine-2-thiolate (4-MePyS, 3) and 6-methylpyridine-2-thiolate (6-MePyS, 4) were synthesized and characterized by spectroscopic means and single-crystal X-ray diffraction analysis (2-4). Complexes 1-4 were reacted with PPh3 and PMe3, respectively, to investigate their oxygen atom transfer (OAT) reactivity and catalytic applicability. Reduction with PPh3 leads to symmetric molybdenum(V) dimers of the general structure [Mo2O3L4] (6-9). Kinetic studies showed that the OAT from [MoO2L2] to PPh3 is 5 times faster for the PymS system than for the PyS and 4-MePyS systems. The reaction of complexes 1-3 with PMe3 gives stable molybdenum(IV) complexes of the structure [MoOL2(PMe3)2] (10-12), while reduction of [MoO2(6-MePyS)2] (4) yields [MoO(6-MePyS)2(PMe3)] (13) with only one PMe3 coordinated to the metal center. The activity of complexes 1-4 in catalytic OAT reactions involving Me2SO and Ph2SO as oxygen donors and PPh3 as an oxygen acceptor has been investigated to assess the influence of the varied ligand frameworks on the OAT reaction rates. It was found that [MoO2(PymS)2] (1) and [MoO2(6-MePyS)2] (4) are similarly efficient catalysts, while complexes 2 and 3 are only moderately active. In the catalytic oxidation of PMe3 with Me2SO, complex 4 is the only efficient catalyst. Complexes 1-4 were also found to catalytically reduce NO3- with PPh3, although their reactivity is inhibited by further reduced species such as NO, as exemplified by the formation of the nitrosyl complex [Mo(NO)(PymS)3] (14), which was identified by single-crystal X-ray diffraction analysis. Computed ΔG⧧ values for the very first step of the OAT were found to be lower for complexes 1 and 4 than for 2 and 3, explaining the difference in catalytic reactivity between the two pairs and revealing the requirement for an electron-deficient ligand system.
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Affiliation(s)
- Madeleine A Ehweiner
- Institute of Chemistry, Inorganic Chemistry, University of Graz, Schubertstrasse 1, 8010 Graz, Austria
| | - Fabian Wiedemaier
- Institute of Chemistry, Physical and Theoretical Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz, Austria
| | - Ferdinand Belaj
- Institute of Chemistry, Inorganic Chemistry, University of Graz, Schubertstrasse 1, 8010 Graz, Austria
| | - Nadia C Mösch-Zanetti
- Institute of Chemistry, Inorganic Chemistry, University of Graz, Schubertstrasse 1, 8010 Graz, Austria
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6
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Wang SY, Dai JW, Chen HB, Zhou ZH. 2,2′-Bipyridine or 1,10-phenanthroline chelated oxomolybdenum(V) complexes with glycolate, lactate and malate in acidic media. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2019.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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7
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Paudel J, Pokhrel A, Kirk ML, Li F. Remote Charge Effects on the Oxygen-Atom-Transfer Reactivity and Their Relationship to Molybdenum Enzymes. Inorg Chem 2019; 58:2054-2068. [PMID: 30673233 DOI: 10.1021/acs.inorgchem.8b03093] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the syntheses, crystal structures, and characterization of the novel cis-dioxomolybdenum(VI) complexes [Tpm*MoVIO2Cl](MoO2Cl3) (1) and [Tpm*MoVIO2Cl](ClO4) (2), which are supported by the charge-neutral tris(3,5-dimethyl-1-pyrazolyl)methane (Tpm*) ligand. A comparison between isostructural [Tpm*MoVIO2Cl]+ and Tp*MoVIO2Cl [Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate] reveals the effects of one unit of overall charge difference on their spectroscopic and electrochemical properties, geometric and electronic structures, and O-atom-transfer (OAT) reactivities, providing new insight into pyranopterin molybdoenzyme OAT reactivity. Computational studies of these molecules indicate that the delocalized positive charge lowers the lowest unoccupied molecular orbital (LUMO) energy of cationic [Tpm*MoO2Cl]+ relative to Tp*MoO2Cl. Despite their virtually identical geometric structures revealed by crystal structures, the MoVI/MoV redox potential of 2 is increased by 350 mV relative to that of Tp*MoVIO2Cl. This LUMO stabilization also contributes to an increased effective electrophilicity of [Tpm*MoO2Cl]+ relative to that of Tp*MoO2Cl, resulting in a more favorable resonant interaction between the molydenum complex LUMO and the highest occupied molecular orbital (HOMO) of the PPh3 substrate. This leads to a greater thermodynamic driving force, an earlier transition state, and a lowered activation barrier for the orbitally controlled first step of the OAT reaction in the Tpm* system relative to the Tp* system. An Eyring plot analysis shows that this initial step yields an O≡MoIV-OPPh3 intermediate via an associative transition state, and the reaction is ∼500-fold faster for 2 than for Tp*MoO2Cl. The second step of the OAT reaction entails solvolysis of the O≡MoIV-OPPh3 intermediate to afford the solvent-substituted MoIV product and is 750-fold faster for the Tpm* system at -15 °C compared to the Tp* system. The observed rate enhancement for the second step is ascribed to a switch of the reaction mechanism from a dissociative pathway for the Tp* system to an alternative associative pathway for the Tpm* system. This is due to a more Lewis acidic MoIV center in the Tpm* system.
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Affiliation(s)
- Jaya Paudel
- Department of Chemistry and Biochemistry , New Mexico State University , Las Cruces , New Mexico 88003 , United States
| | - Amrit Pokhrel
- Department of Chemistry and Chemical Biology , The University of New Mexico , Albuquerque , New Mexico 87131 , United States
| | - Martin L Kirk
- Department of Chemistry and Chemical Biology , The University of New Mexico , Albuquerque , New Mexico 87131 , United States
| | - Feifei Li
- Department of Chemistry and Biochemistry , New Mexico State University , Las Cruces , New Mexico 88003 , United States
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8
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Castiñeira Reis M, Marín-Luna M, Silva López C, Faza ON. Mechanism of the Molybdenum-Mediated Cadogan Reaction. ACS OMEGA 2018; 3:7019-7026. [PMID: 31458865 PMCID: PMC6644586 DOI: 10.1021/acsomega.8b01278] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 06/13/2018] [Indexed: 05/24/2023]
Abstract
Oxygen atom transfer reactions are receiving increasing attention because they bring about paramount transformations in the current biomass processing industry. Significant efforts have therefore been made lately in the development of efficient and scalable methods to deoxygenate organic compounds. One recent alternative involves the modification of the Cadogan reaction in which a Mo(VI) core catalyzes the reduction of o-nitrostyrene derivatives to indoles in the presence of PPh3. We have used density functional theory calculations to perform a comprehensive mechanistic study on this transformation, in which we find two clearly defined stages: an associative path from the nitro to the nitroso compound, characterized by the reduction of the catalyst in the first step, and a peculiar mechanism involving oxazaphosphiridine and nitrene intermediates leading to an indole product, where the metal catalyst does not participate.
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Affiliation(s)
- Marta Castiñeira Reis
- Departamento
de Química Orgánica, Universidade de Vigo, Campus Lagoas-Marcosende, 36310 Vigo, Spain
| | - Marta Marín-Luna
- Departamento
de Química Orgánica, Universidade de Vigo, Campus Lagoas-Marcosende, 36310 Vigo, Spain
| | - Carlos Silva López
- Departamento
de Química Orgánica, Universidade de Vigo, Campus Lagoas-Marcosende, 36310 Vigo, Spain
| | - Olalla Nieto Faza
- Departamento
de Química Orgánica, Universidade de Vigo, Campus As Lagoas, 32004 Orense, Spain
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9
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Wang SY, Dong X, Zhou ZH. N-hetercycle dimeric molybdenum(V) complexes with strong interactions and their catalytic degradations of methyl orange. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2018.03.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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10
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Moradi-Shoeili Z, Zare M. The Effect of Substituents on Catalytic Performance of bis-Thiosemicarbazone Mo(VI) Complexes: Synthesis and Spectroscopic, Electrochemical, and Functional Properties. KINETICS AND CATALYSIS 2018. [DOI: 10.1134/s002315841802012x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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11
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Elrod LT, Kim E. Lewis Acid Assisted Nitrate Reduction with Biomimetic Molybdenum Oxotransferase Complex. Inorg Chem 2018; 57:2594-2602. [PMID: 29443517 DOI: 10.1021/acs.inorgchem.7b02956] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reduction of nitrate (NO3-) to nitrite (NO2-) is of significant biological and environmental importance. While MoIV(O) and MoVI(O)2 complexes that mimic the active site structure of nitrate reducing enzymes are prevalent, few of these model complexes can reduce nitrate to nitrite through oxygen atom transfer (OAT) chemistry. We present a novel strategy to induce nitrate reduction chemistry of a previously known catalyst MoIV(O)(SN)2 (2), where SN = bis(4- tert-butylphenyl)-2-pyridylmethanethiolate, that is otherwise incapable of achieving OAT with nitrate. Addition of nitrate with the Lewis acid Sc(OTf)3 (OTf = trifluoromethanesulfonate) to 2 results in an immediate and clean conversion of 2 to MoVI(O)2(SN)2 (1). The Lewis acid additive further reacts with the OAT product, nitrite, to form N2O and O2. This work highlights the ability of Sc3+ additives to expand the reactivity scope of an existing MoIV(O) complex together with which Sc3+ can convert nitrate to stable gaseous molecules.
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Affiliation(s)
- Lee Taylor Elrod
- Department of Chemistry , Brown University , Providence , Rhode Island 02912 , United States
| | - Eunsuk Kim
- Department of Chemistry , Brown University , Providence , Rhode Island 02912 , United States
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12
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Saswati, Roy S, Dash SP, Acharyya R, Kaminsky W, Ugone V, Garribba E, Harris C, Lowe JM, Dinda R. Chemistry of oxidomolybdenum(IV) and -(VI) complexes with ONS donor ligands: Synthesis, computational evaluation and oxo-transfer reactions. Polyhedron 2018. [DOI: 10.1016/j.poly.2017.12.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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13
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Acid-facilitated product release from a Mo(IV) center: relevance to oxygen atom transfer reactivity of molybdenum oxotransferases. J Biol Inorg Chem 2017; 23:193-207. [PMID: 29177705 DOI: 10.1007/s00775-017-1518-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 11/10/2017] [Indexed: 01/27/2023]
Abstract
We report that pyridinium ions (HPyr+) accelerate the conversion of [Tp*MoIVOCl(OPMe3)] (1) to [Tp*MoIVOCl(NCCH3)] (2) by 103-fold, affording 2 in near-quantitative yield; Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate. This novel reactivity and the mechanism of this reaction were investigated in detail. The formation of 2 followed pseudo-first-order kinetics, with the observed pseudo-first-order rate constant (k obs) linearly correlated with [HPyr+]. An Eyring plot revealed that this HPyr+-facilitated reaction has a small positive value of ∆S ‡ indicative of a dissociative interchange (Id) mechanism, different from the slower associative interchange (Ia) mechanism in the absence of HPyr+ marked with a negative ∆S ‡. Interestingly, log(k obs) was found to be linearly correlated to the acidity of substituted pyridinium ions. This novel reactivity is further investigated using combined DFT and ab initio coupled cluster methods. Different reaction pathways, including Id, Ia, and possible alternative routes in the absence or presence of HPyr+, were considered, and enthalpy and free energies were calculated for each pathway. Our computational results further underscored that the Id route is energetically favored in the presence of HPyr+, in contrast with the preferred Ia-NNO pathway in the absence of HPyr+. Our computational results also revealed molecular-level details for the HPyr+-facilitated Id route. Specifically, HPyr+ initially becomes hydrogen-bonded to the oxygen atom of the Mo(IV)-OPMe3 moiety, which lowers the activation barrier for the Mo-OPMe3 bond cleavage in a rate-limiting step to dissociate the OPMe3 product. The implications of our results were discussed in the context of molybdoenzymes, particularly the reductive half-reaction of sulfite oxidase.
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14
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Castiñeira Reis M, Marín-Luna M, Silva López C, Faza ON. [MoO 2] 2+-Mediated Oxygen Atom Transfer via an Unusual Lewis Acid Mechanism. Inorg Chem 2017; 56:10570-10575. [PMID: 28829586 DOI: 10.1021/acs.inorgchem.7b01529] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Density functional theory is applied to the study of the oxygen atom transfer reaction from sulfoxide (DMSO) to phosphine (PMe3) catalyzed by the [MoO2]2+ active core. In this work, two fundamentally different roles are explored for this dioxometal complex in the first step of the catalytic cycle: as an oxidizing agent and as a Lewis acid. The latter turns out to be the favored pathway for the oxygen atom transfer. This finding may have more general implications for similar reactions catalyzed by the same [MoO2]2+ core.
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Affiliation(s)
- Marta Castiñeira Reis
- Departamento de Quı́mica Orgánica, Universidade de Vigo , Lagoas-Marcosende, 36310 Vigo, Spain
| | - Marta Marín-Luna
- Departamento de Quı́mica Orgánica, Universidade de Vigo , Lagoas-Marcosende, 36310 Vigo, Spain
| | - Carlos Silva López
- Departamento de Quı́mica Orgánica, Universidade de Vigo , Lagoas-Marcosende, 36310 Vigo, Spain
| | - Olalla Nieto Faza
- Departamento de Quı́mica Orgánica, Universidade de Vigo , Campus As Lagoas, 32004 Ourense, Spain
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15
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Affiliation(s)
- Charles G. Young
- Department of Chemistry and PhysicsLa Trobe Institute for Molecular ScienceLa Trobe University3086MelbourneVictoriaAustralia
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16
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Yang J, Mogesa B, Basu P, Kirk ML. Large Ligand Folding Distortion in an Oxomolybdenum Donor-Acceptor Complex. Inorg Chem 2015; 55:785-93. [PMID: 26692422 DOI: 10.1021/acs.inorgchem.5b02252] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Interligand charge transfer is examined in the novel metallo-dithiolene complex MoO(SPh)2((i)Pr2Dt(0)) (where (i)Pr2Dt(0) = N,N'-isopropyl-piperazine-2,3-dithione). The title complex displays a remarkable 70° "envelope"-type fold of the five-membered dithiolene ring, which is bent upward toward the terminal oxo ligand. A combination of electronic absorption and resonance Raman spectroscopies have been used to probe the basic electronic structure responsible for the large fold-angle distortion. The intense charge transfer transition observed at ∼18 000 cm(-1) is assigned as a thiolate → dithione ligand-to-ligand charge transfer (LL'CT) transition that also possesses Mo(IV) → dithione charge transfer character. Strong orbital mixing between occupied and virtual orbitals with Mo(x(2)-y(2)) orbital character is derived from a strong pseudo Jahn-Teller effect, which drives the large fold-angle distortion to yield a double-well potential in the electronic ground state.
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Affiliation(s)
- Jing Yang
- Department of Chemistry and Chemical Biology, The University of New Mexico , MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
| | - Benjamin Mogesa
- Department of Chemistry and Biochemistry, Duquesne University , Pittsburgh, Pennsylvania 15282, United States
| | - Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University , Pittsburgh, Pennsylvania 15282, United States
| | - Martin L Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico , MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
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17
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Pimkov IV, Serli-Mitasev B, Peterson AA, Ratvasky SC, Hammann B, Basu P. Designing the Molybdopterin Core through Regioselective Coupling of Building Blocks. Chemistry 2015; 21:17057-72. [DOI: 10.1002/chem.201502845] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Indexed: 01/08/2023]
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18
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Ducrot A, Scattergood B, Coulson B, Perutz RN, Duhme-Klair AK. Electronic Fine-Tuning of Oxygen Atom Transfer Reactivity ofcis-Dioxomolybdenum(VI) Complexes with Thiosemicarbazone Ligands. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201500059] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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19
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Moradi-Shoeili Z, Zare M, Bagherzadeh M, Kubicki M, Boghaei DM. Synthesis, structural characterization, and catalytic reactivity of a new molybdenum(VI) complex containing 1,3,4-thiadiazole derivative as a tridentate NNO donor ligand. J COORD CHEM 2015. [DOI: 10.1080/00958972.2014.993321] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Zeinab Moradi-Shoeili
- Department of Chemistry, Sharif University of Technology, Tehran, Iran
- Faculty of Sciences, Department of Chemistry, University of Guilan, Rasht, Iran
| | - Maryam Zare
- Department of Chemistry, Sharif University of Technology, Tehran, Iran
- Materials Science & Engineering Department, Golpayegan University of Technology, Golpayegan, Iran
| | | | - Maciej Kubicki
- Faculty of Chemistry, Adam Mickiewicz University, Poznan, Poland
| | - Davar M. Boghaei
- Department of Chemistry, Sharif University of Technology, Tehran, Iran
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Synthesis and properties of a molybdenum Schiff base electrocatalyst for generating hydrogen from acetic acid. TRANSIT METAL CHEM 2014. [DOI: 10.1007/s11243-014-9878-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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21
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Sparacino-Watkins C, Stolz JF, Basu P. Nitrate and periplasmic nitrate reductases. Chem Soc Rev 2014; 43:676-706. [PMID: 24141308 DOI: 10.1039/c3cs60249d] [Citation(s) in RCA: 189] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The nitrate anion is a simple, abundant and relatively stable species, yet plays a significant role in global cycling of nitrogen, global climate change, and human health. Although it has been known for quite some time that nitrate is an important species environmentally, recent studies have identified potential medical applications. In this respect the nitrate anion remains an enigmatic species that promises to offer exciting science in years to come. Many bacteria readily reduce nitrate to nitrite via nitrate reductases. Classified into three distinct types--periplasmic nitrate reductase (Nap), respiratory nitrate reductase (Nar) and assimilatory nitrate reductase (Nas), they are defined by their cellular location, operon organization and active site structure. Of these, Nap proteins are the focus of this review. Despite similarities in the catalytic and spectroscopic properties Nap from different Proteobacteria are phylogenetically distinct. This review has two major sections: in the first section, nitrate in the nitrogen cycle and human health, taxonomy of nitrate reductases, assimilatory and dissimilatory nitrate reduction, cellular locations of nitrate reductases, structural and redox chemistry are discussed. The second section focuses on the features of periplasmic nitrate reductase where the catalytic subunit of the Nap and its kinetic properties, auxiliary Nap proteins, operon structure and phylogenetic relationships are discussed.
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22
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Affiliation(s)
- Russ Hille
- Department of Biochemistry, University of California, Riverside, Riverside, California 92521, United States
| | - James Hall
- Department of Biochemistry, University of California, Riverside, Riverside, California 92521, United States
| | - Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, United States
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23
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Pimkov IV, Nigam A, Venna K, Fleming FF, Solntsev PV, Nemykin VN, Basu P. Dithiolopyranthione Synthesis, Spectroscopy and an Unusual Reactivity with DDQ. J Heterocycl Chem 2013; 50:879-886. [PMID: 25328243 PMCID: PMC4200397 DOI: 10.1002/jhet.1715] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The bicyclic pyran thiolone tetrahydro-3αH-[1,3]dithiolo[4,5-β]pyran-2-thione (3a) engages in a highly unusual fragmentation in the presence of DDQ. The pyran thiolone, 3a, was synthesized by chlorination of 3,4-dihydro-2H-pyran (1), followed by condensing with CS2 and NaSH. Reaction of 3a with DDQ generates the isomerized pyran thiolone tetrahydro-3αH-[1,3]dithiolo[4,5-β]pyran-2-thione (3b) and 4-benzyl-5-(3-hydroxypropyl)-1,3-dithiole-2-thione (4) via a deep-seated rearrangement. The identity of 3b was confirmed by single crystal X-ray analysis: P21/c, a=5.807(9) Å, b = 12.99(2) Å, c = 11.445(15), β=113.23(6)°. Mechanistic experiments and computational insight is used to explain the likely sequence of events in the highly unusual formation of 4. Collectively, these results establish fundamental reactivity patterns for further research in this area.
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Affiliation(s)
- Igor V. Pimkov
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282
| | - Archana Nigam
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282
| | - Kiran Venna
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282
| | - Fraser F. Fleming
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282
| | - Pavlo V. Solntsev
- Department of Chemistry, The University of Minnesota-Duluth, Duluth, MN 55812
| | - Victor N. Nemykin
- Department of Chemistry, The University of Minnesota-Duluth, Duluth, MN 55812
| | - Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282
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24
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Jensen LM, Abrahams BF, Young CG. Water-soluble scorpionate ligands and their reactions with molybdenum complexes. Crystal structures of lithium tris(3-isopropylpyrazol-1-yl)methanesulfonate and MoVOCl3(OPPh3)2·MoVIO2Cl2(OPPh3)2. J COORD CHEM 2013. [DOI: 10.1080/00958972.2013.778988] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
| | | | - Charles G. Young
- a School of Chemistry, University of Melbourne , Parkville , Australia
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25
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Mitra J, Sarkar S. Oxo-Mo(IV)(dithiolene)thiolato complexes: analogue of reduced sulfite oxidase. Inorg Chem 2013; 52:3032-42. [PMID: 23461669 DOI: 10.1021/ic302485c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A series of [Mo(IV)O(mnt)(SR)(N-N)](-) (mnt = maleonitriledithiolate; R = Ph, nap, p-Cl-Ph, p-CO2H-Ph, and p-NO2-Ph; N-N = 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen)) complexes analogous to the reduced active site of enzymes of the sulfite oxidase family has been synthesized and their participation in electron transfer reactions studied. Equatorial thiolate and dithiolene ligations have been used to closely simulate the three sulfur coordinations present in the native molybdenum active site. These synthetic analogues have been shown to participate in electron transfer via a pentavalent EPR-active Mo(V) intermediate with minimal structural change as observed electrochemically by reversible oxidative responses. The role of the redox-active dithiolene ligand as an electron transfer gate between external oxidants and the molybdenum center could be envisaged in one of the analogue systems where the initial transient EPR signal with <g> = 2.008 is replaced by the appearance of a typical Mo(V)-centered EPR (<g> = 1.976) signal. The appearance of such a ligand-based transient radical at the initial stage has been supported by the ligand-centered frontier orbital from DFT calculation. A stepwise rationale has been provided by computational study to show that the coupled effects of the diimine bite angle and the thiolato dihedral angle determine the metal- or ligand-based frontier orbital occupancy. DFT calculation has further supported the similarity between the reduced, semireduced, and oxidized resting state of the molybdenum center in Moco of SO with the synthesized complexes and their corresponding one-electron and fully oxidized species.
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Affiliation(s)
- Joyee Mitra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, Uttar Pradesh, India
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26
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Moradi-Shoeili Z, Boghaei DM, Amini M, Bagherzadeh M, Notash B. New molybdenum(VI) complex with ONS-donor thiosemicarbazone ligand: Preparation, structural characterization, and catalytic applications in olefin epoxidation. INORG CHEM COMMUN 2013. [DOI: 10.1016/j.inoche.2012.10.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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27
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Basu P, Kail BW, Adams AK, Nemykin VN. Quantitation of the ligand effect in oxo-transfer reactions of dioxo-Mo(VI) trispyrazolyl borate complexes. Dalton Trans 2012; 42:3071-81. [PMID: 23212540 DOI: 10.1039/c2dt32349d] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The oxygen atom transfer reactivity (OAT) of dioxo-Mo(VI) complexes of hydrotrispyrazolyl borate (hydrotris(3,5-dimethylpyrazolyl)borate, Tp(Me2); hydrotris(3-isopropylpyrazol-1-yl)borate, Tp(iPr)) with tertiary phosphines (PMe(3), PMe(2)Ph, PEt(3), PEt(2)Ph, PBu(n)(3), PMePh(2), or PEtPh(2)) has been investigated. In acetonitrile, these reactions proceed via the formation of a phosphoryl intermediate complex that undergoes a solvolysis reaction. We report the synthesis and characterization of several phosphoryl complexes. The rates of formation of phosphoryl complexes and their solvation were determined by spectrophotometry. The rates of the reactions and the properties of the phosphoryl species were investigated using the Quantitative Analysis of Ligand Effect (QALE) methodology. The results show that, at least in this system, the first step of the reaction is controlled primarily by the steric factor, and in the second step, both electronic and steric factors are important. We also analyzed the effect of ligands on the reaction rate i.e., Tp(Me2)vs. Tp(iPr).
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Affiliation(s)
- Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15228, USA.
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28
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Tenderholt AL, Hodgson KO, Hedman B, Holm RH, Solomon EI. Substrate and metal control of barrier heights for oxo transfer to Mo and W bis-dithiolene sites. Inorg Chem 2012; 51:3436-42. [PMID: 22372518 DOI: 10.1021/ic2020397] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Reaction coordinates for oxo transfer from the substrates Me(3)NO, Me(2)SO, and Me(3)PO to the biologically relevant Mo(IV) bis-dithiolene complex [Mo(OMe)(mdt)(2)](-) where mdt = 1,2-dimethyl-ethene-1,2-dithiolate(2-), and from Me(2)SO to the analogous W(IV) complex, have been calculated using density functional theory. In each case, the reaction first proceeds through a transition state (TS1) to an intermediate with substrate weakly bound, followed by a second transition state (TS2) around which breaking of the substrate X-O bond begins. By analyzing the energetic contributions to each barrier, it is shown that the nature of the substrate and metal determines which transition state controls the rate-determining step of the reaction.
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Affiliation(s)
- Adam L Tenderholt
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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29
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Matsushita O, Derkacheva VM, Muranaka A, Shimizu S, Uchiyama M, Luk’yanets EA, Kobayashi N. Rectangular-Shaped Expanded Phthalocyanines with Two Central Metal Atoms. J Am Chem Soc 2012; 134:3411-8. [DOI: 10.1021/ja209589x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Osamu Matsushita
- Department of Chemistry, Graduate
School of Science, Tohoku University, Sendai
980-8578, Japan
| | | | - Atsuya Muranaka
- Advanced Elements
Chemistry Research
Team, ASI, RIKEN, Wako 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Saitama 332-0012, Japan
| | - Soji Shimizu
- Department of Chemistry, Graduate
School of Science, Tohoku University, Sendai
980-8578, Japan
| | - Masanobu Uchiyama
- Advanced Elements
Chemistry Research
Team, ASI, RIKEN, Wako 351-0198, Japan
- Graduate School of Pharmaceutical
Sciences, The University of Tokyo, Bunkyo-ku,
Tokyo 113-0033, Japan
| | - Evgeny A. Luk’yanets
- Organic Intermediates and Dyes Institute, B. Sadovaya 1/4, Moscow 123995,
Russia
| | - Nagao Kobayashi
- Department of Chemistry, Graduate
School of Science, Tohoku University, Sendai
980-8578, Japan
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30
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Volpe M, Mösch-Zanetti NC. Molybdenum(VI) Dioxo and Oxo-Imido Complexes of Fluorinated β-Ketiminato Ligands and Their Use in OAT Reactions. Inorg Chem 2012; 51:1440-9. [DOI: 10.1021/ic201681u] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Manuel Volpe
- Institut für Chemie, Bereich Anorganische
Chemie, Karl-Franzens-Universität, Graz Stremayrgasse
16, A-8010 Graz, Austria
| | - Nadia C. Mösch-Zanetti
- Institut für Chemie, Bereich Anorganische
Chemie, Karl-Franzens-Universität, Graz Stremayrgasse
16, A-8010 Graz, Austria
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31
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Sugimoto H, Tano H, Miyake H, Itoh S. Generation of bis(dithiolene)dioxomolybdenum(vi) complexes from bis(dithiolene)monooxomolybdenum(iv) complexes by proton-coupled electron transfer in aqueous media. Dalton Trans 2011; 40:2358-65. [DOI: 10.1039/c0dt00763c] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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32
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Mayilmurugan R, Harum BN, Volpe M, Sax AF, Palaniandavar M, Mösch‐Zanetti NC. Mechanistic Insight into the Reactivity of Oxotransferases by Novel Asymmetric Dioxomolybdenum(VI) Model Complexes. Chemistry 2010; 17:704-13. [DOI: 10.1002/chem.201001177] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 08/27/2010] [Indexed: 11/06/2022]
Affiliation(s)
- Ramasamy Mayilmurugan
- Institut für Chemie, Bereich Anorganische Chemie, Karl‐Franzens‐Universität Graz, Schubertstrasse 1, 8010, Graz (Austria), Fax: (+43) 316‐380‐9835
| | - Bastian N. Harum
- Institut für Chemie, Bereich Anorganische Chemie, Karl‐Franzens‐Universität Graz, Schubertstrasse 1, 8010, Graz (Austria), Fax: (+43) 316‐380‐9835
| | - Manuel Volpe
- Institut für Chemie, Bereich Anorganische Chemie, Karl‐Franzens‐Universität Graz, Schubertstrasse 1, 8010, Graz (Austria), Fax: (+43) 316‐380‐9835
| | - Alexander F. Sax
- Institut für Chemie, Bereich Physikalische und Theoretische Chemie, Karl‐Franzens‐Universität Graz, Heinrichstrasse 28/VI, 8010, Graz (Austria)
| | | | - Nadia C. Mösch‐Zanetti
- Institut für Chemie, Bereich Anorganische Chemie, Karl‐Franzens‐Universität Graz, Schubertstrasse 1, 8010, Graz (Austria), Fax: (+43) 316‐380‐9835
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33
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Ng VWL, Taylor MK, Hill LMR, White JM, Young CG. Novel
O
,
O′
‐Donor Oxo‐Mo
IV
Hydrotris(3‐isopropylpyrazolyl)borate Complexes Formed by Chelation of Potentially Hydrogen‐Bonding Phenolate Ligands on Reduction of Dioxo‐Mo
VI
Complexes. Eur J Inorg Chem 2010. [DOI: 10.1002/ejic.201000214] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Victor W. L. Ng
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia, Fax: +613‐349‐5180
| | - Michelle K. Taylor
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia, Fax: +613‐349‐5180
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia, Fax: +613‐349‐5180
| | - Lyndal M. R. Hill
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia, Fax: +613‐349‐5180
| | - Jonathan M. White
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia, Fax: +613‐349‐5180
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia, Fax: +613‐349‐5180
| | - Charles G. Young
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia, Fax: +613‐349‐5180
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34
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Basu P, Kail BW, Young CG. Influence of the oxygen atom acceptor on the reaction coordinate and mechanism of oxygen atom transfer from the dioxo-Mo(VI) complex, Tp(iPr)MoO(2)(OPh), to tertiary phosphines. Inorg Chem 2010; 49:4895-900. [PMID: 20433155 PMCID: PMC2897133 DOI: 10.1021/ic902500h] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The oxygen atom transfer reactivity of the dioxo-Mo(VI) complex, Tp(iPr)MoO(2)(OPh) (Tp(iPr) = hydrotris(3-isopropylpyrazol-1-yl)borate), with a range of tertiary phosphines (PMe(3), PMe(2)Ph, PEt(3), PBu(n)(3), PEt(2)Ph, PEtPh(2), and PMePh(2)) has been investigated. The first step in all the reactions follows a second-order rate law indicative of an associative transition state, consistent with nucleophilic attack by the phosphine on an oxo ligand, namely, Tp(iPr)MoO(2)(OPh) + PR(3) --> Tp(iPr)MoO(OPh)(OPR(3)). The calculated free energy of activation for the formation of the OPMe(3) intermediate (Chem. Eur. J. 2006, 12, 7501) is in excellent agreement with the experimental DeltaG() value reported here. The second step of the reaction, that is, the exchange of the coordinated phosphine oxide by acetonitrile, Tp(iPr)MoO(OPh)(OPR(3)) + MeCN --> Tp(iPr)MoO(OPh)(MeCN) + OPR(3), is first-order in starting complex in acetonitrile. The reaction occurs via a dissociative interchange (I(d)) or associative interchange (I(a)) mechanism, depending on the nature of the phosphine oxide. The activation parameters for the solvolysis of Tp(iPr)MoO(OPh)(OPMe(3)) (DeltaH(++) = 56.3 kJ mol(-1); DeltaS(++) = -125.9 J mol(-1) K(-1); DeltaG(++) = 93.8 kJ mol(-1)) and Tp(iPr)MoO(OPh)(OPEtPh(2)) (DeltaH(++) = 66.5 kJ mol(-1); DeltaS(++) = -67.6 J mol(-1) K(-1); DeltaG(++) = 86.7 kJ mol(-1)) by acetonitrile are indicative of I(a) mechanisms. In contrast, the corresponding parameters for the solvolysis reaction of Tp(iPr)MoO(OPh)(OPEt(3)) (DeltaH(++) = 95.8 kJ mol(-1); DeltaS(++) = 26.0 J mol(-1) K(-1); DeltaG(++) = 88.1 kJ mol(-1)) and the remaining complexes by the same solvent are indicative of an I(d) mechanism. The equilibrium constant for the solvolysis of the oxo-Mo(V) phosphoryl complex, [Tp(iPr)MoO(OPh)(OPMe(3))](+), by acetonitrile was calculated to be 1.9 x 10(-6). The oxo-Mo(V) phosphoryl complex is more stable than the acetonitrile analogue, whereas the oxo-Mo(IV) acetonitrile complex is more stable than the phosphoryl analogue. The higher stability of the Mo(V) phosphoryl complex may explain the phosphate inhibition of sulfite oxidase.
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Affiliation(s)
- Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, Pennsylvania 15282, USA.
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35
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Sugimoto H, Tatemoto S, Suyama K, Miyake H, Itoh S, Dong C, Yang J, Kirk ML. Dioxomolybdenum(VI) complexes with ene-1,2-dithiolate ligands: synthesis, spectroscopy, and oxygen atom transfer reactivity. Inorg Chem 2010; 48:10581-90. [PMID: 19831360 DOI: 10.1021/ic901112s] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
New dioxomolybdenum(VI) complexes, (Et(4)N)(Ph(4)P)[Mo(VI)O(2)(S(2)C(2)(CO(2)Me)(2))(bdt)] (2) and (Et(4)N)(Ph(4)P)[Mo(VI)O(2)(S(2)C(2)(CO(2)Me)(2))(bdtCl(2))](4)(S(2)C(2)(CO(2)Me)(2) = 1,2-dicarbomethoxyethylene-1,2-ditholate, bdt = 1,2-benzenedithiolate, bdtCl(2) = 3,6-dichloro-1,2-benzenedithiolate), that possess at least one ene-1,2-dithiolate ligand were synthesized by the reaction of their mono-oxo-molybdenum(IV) derivatives, (Et(4)N)(2)[Mo(IV)O(S(2)C(2)(CO(2)Me)(2))(bdt)] (1) and (Et(4)N)(2)[Mo(IV)O(S(2)C(2)(CO(2)Me)(2))(bdtCl(2))] (3), with Me(3)NO. Additionally, the bis(ene-1,2-dithiolate)Mo(VI)O(2) complex, (Et(4)N)(Ph(4)P)[Mo(VI)O(2)(S(2)C(2)(CO(2)Me)(2))(2)] (6), was isolated. Complexes 2, 4, and 6 were characterized by elemental analysis, negative-ion ESI mass spectrometry, and IR spectroscopy. X-ray analysis of 4 and 6 revealed a Mo(VI) center that adopts a distorted octahedral geometry. Variable-temperature (1)H NMR spectra of (CD(3))(2)CO solutions of the Mo(VI)O(2) complexes indicated that the Mo centers isomerize between Delta and Lambda forms. The electronic structures of 2, 4, and 6 have been investigated by electronic absorption and resonance Raman spectroscopy and bonding calculations. The results indicate very similar electronic structures for the complexes and considerable pi-delocalization between the Mo(VI)O(2) and ene-1,2-dithiolate units. The similar oxygen atom transfer kinetics for the complexes results from their similar electronic structures.
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Affiliation(s)
- Hideki Sugimoto
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
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