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Atta S, Mandal A, Saha R, Majumdar A. Reduction of nitrite to nitric oxide and generation of reactive chalcogen species by mononuclear Fe(II) and Zn(II) complexes of thiolate and selenolate. Dalton Trans 2024; 53:949-965. [PMID: 38126213 DOI: 10.1039/d3dt03768a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Comparative reactivity of a series of new Zn(II) and Fe(II) compounds, [(Py2ald)M(ER)] (E = S, R = Ph: M = Zn, 1aZn; M = Fe, 1aFe; E = S, R = 2,6-Me2-C6H3: M = Zn, 1bZn; M = Fe, 1bFe; E = Se, R = Ph: M = Zn, 2Zn; M = Fe, 2Fe), and [(Py2ald)M]22+ (M = Zn, 5Zn; M = Fe, 5Fe) is presented. Compound 1aZn could react with nitrite (NO2-) to produce [(Py2ald)Zn(ONO)] (3Zn), which, upon treatment with thiols and PhSeH (proton source), could regenerate either 1aZn/5Zn and 2Zn respectively, along with the production of nitric oxide (NO) where the yield of NO increases in the order tBuSH ≪ PhCH2SH < PhSH < PhSeH. In contrast to this, 1aFe, 2Fe and 5Fe could affect the direct reduction of NO2- in the absence of protons to generate NO and [{(Py2ald)(ONO)Fe}2-μ2-O] (8Fe). Moreover, 8Fe could regenerate 5Fe and 1aFe/2Fe upon treatment with 4 and 6 equiv. of PhEH (E = S/Se), respectively, along with the generation of NO. Finally, a comparative study of the mononuclear Zn(II) and Fe(II) compounds for the transfer of the coordinated thiolate/selenolate and the generation and transfer of reactive sulfur/selenium species (RES-, E = Se, S) to a series of organic substrates has been provided.
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Affiliation(s)
- Sayan Atta
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata 700032, West Bengal, India.
| | - Amit Mandal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata 700032, West Bengal, India.
| | - Rahul Saha
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata 700032, West Bengal, India.
| | - Amit Majumdar
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata 700032, West Bengal, India.
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Lin WS, Kuwata S. Recent Developments in Reactions and Catalysis of Protic Pyrazole Complexes. Molecules 2023; 28:molecules28083529. [PMID: 37110763 PMCID: PMC10143336 DOI: 10.3390/molecules28083529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 04/12/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
Protic pyrazoles (N-unsubstituted pyrazoles) have been versatile ligands in various fields, such as materials chemistry and homogeneous catalysis, owing to their proton-responsive nature. This review provides an overview of the reactivities of protic pyrazole complexes. The coordination chemistry of pincer-type 2,6-bis(1H-pyrazol-3-yl)pyridines is first surveyed as a class of compounds for which significant advances have made in the last decade. The stoichiometric reactivities of protic pyrazole complexes with inorganic nitrogenous compounds are then described, which possibly relates to the inorganic nitrogen cycle in nature. The last part of this article is devoted to outlining the catalytic application of protic pyrazole complexes, emphasizing the mechanistic aspect. The role of the NH group in the protic pyrazole ligand and resulting metal-ligand cooperation in these transformations are discussed.
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Affiliation(s)
- Wei-Syuan Lin
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Shigeki Kuwata
- Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu 525-8577, Shiga, Japan
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Partovi S, Xiong Z, Kulesa KM, Smith JM. Electrocatalytic Reduction of Nitrogen Oxyanions with a Redox-Active Cobalt Macrocycle Complex. Inorg Chem 2022; 61:9034-9039. [PMID: 35666148 DOI: 10.1021/acs.inorgchem.2c00199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cobalt complex, [Co(CR)Br2]+, where CR is the redox-active macrocycle 2,12-dimethyl-3,7,11,17-tetraazabicyclo-[11.3.1]-heptadeca-1(17),2,11,13,15-pentaene, has been investigated for the electrocatalytic reduction of aqueous NO2- and NO3-. At neutral pH, the bromide ligands are hydrolyzed, providing [Co(CR)(OH2)(OH)]2+ as the major species in aqueous solution. In the presence of nitrite, [Co(CR)(NO2)2]+ is formed as the major species in solution and is a precursor to the electrocatalytic reduction of NO2-, which is selectively converted to ammonium with high Faradaic efficiency. There is evidence for both homogeneous and heterogeneous electrocatalysis. Although similar NO3- binding is not observed, electrocatalytic reduction to ammonium also occurs, albeit with a lower Faradaic efficiency. In this case, NO2- is generated as an intermediate product of NO3- reduction.
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Affiliation(s)
- Sheyda Partovi
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Ziqing Xiong
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Krista M Kulesa
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Jeremy M Smith
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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Gupta S, Vijayan S, Bertke JA, Kundu S. NO Generation from the Cross-Talks between Ene-diol Antioxidants and Nitrite at Metal Sites. Inorg Chem 2022; 61:8477-8483. [PMID: 35612531 DOI: 10.1021/acs.inorgchem.2c00364] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The one-electron reduction of nitrite (NO2-) to nitric oxide (NO) and ene-diol oxidation are two important biochemical transformations. Employing mononuclear cobalt-nitrite complexes with CoIII and CoII oxidation states, [(Bz3Tren)CoIII(nitrite)2](ClO4) (1) and [(Bz3Tren)CoII(nitrite)](ClO4) (2), this report illustrates NO release coupled to stepwise oxidation of ene-diol antioxidants such as l-ascorbic acid (AH2) and catechol. Analysis of the AH2 end-product reveals that the reaction with complex 1 affords dehydroascorbic acid. Intriguingly, a controlled oxidation of AH2 with complex 2 results in a [CoII]-bound ascorbyl radical-anion (8). Finally, NO release with the concomitant generation of metal-bound 3,5-di-tert-butyl-semiquinone radical anion from the reactions of 3,5-di-tert-butyl-catechol and [(Bz3Tren)MII(nitrite)](ClO4) (2, M = Co; 4, M = Zn) provides mechanistic insights into the cross-talk between nitrite and ene-diols at the metal sites.
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Affiliation(s)
- Shourya Gupta
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM), Thiruvananthapuram 695551, India
| | - Swathy Vijayan
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM), Thiruvananthapuram 695551, India
| | - Jeffery A Bertke
- Department of Chemistry, Georgetown University, Box 571227-1227, Washington, District of Columbia 20057, United States
| | - Subrata Kundu
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM), Thiruvananthapuram 695551, India
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Popp J, Riggenmann T, Schröder D, Ampßler T, Salvador P, Klüfers P. Bent and Linear {CoNO} 8 Entities: Structure and Bonding in a Prototypic Class of Nitrosyls. Inorg Chem 2021; 60:15980-15996. [PMID: 34612642 DOI: 10.1021/acs.inorgchem.1c00998] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Among the isoelectronic ligands CN-, CO, and NO+, an oblique bonding to the metal is well-established for the nitrosyl ligand, with M-N-O angles down to ≈120°. In the last decades, the nitrosyl community got into the habit of addressing a bent-bonded nitrosyl ligand as 1NO-. Thus, because various redox forms of a nitrosyl ligand seem to exist, the ligand is considered to be "noninnocent" because of the obvious ambiguity of an oxidation state (OS) assignment of the ligand and metal. Among the bent-bonded species, the low-spin {CoNO}8 class is prototypic. From this class, some 20 new nitrosyl compounds, the X-ray structure determinations of which comply with strict quality criteria, were analyzed with respect to the OS issue. As a result, the effective OS method shows a low-spin d8 CoI-NO+ couple instead of a negative OS of the ligand at the BP86/def2-TZVP (+D3, +CPCM with infinite permittivity) level of theory. The same holds for some new members of the linear subclass of {CoNO}8 compounds. For all compounds, a largely invariable "real" charge of ≈ -0.3 e was obtained from population analyses. All of these electron-rich d8 species strive to manage Pauli repulsion between the metal electrons and the lone pair at the nitrosyl's nitrogen atom, with the bending of the CoNO unit as the most frequent escape.
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Affiliation(s)
- Jens Popp
- Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstraße 5-13, 81377 Munich, Germany
| | - Tobias Riggenmann
- Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstraße 5-13, 81377 Munich, Germany
| | - Daniel Schröder
- Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstraße 5-13, 81377 Munich, Germany
| | - Torsten Ampßler
- Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstraße 5-13, 81377 Munich, Germany
| | - Pedro Salvador
- Institut de Química Computacional i Catàlisi i Departament de Química, Universitat de Girona, Maria Aurèlia Capmany 69, 17003 Girona, Spain
| | - Peter Klüfers
- Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstraße 5-13, 81377 Munich, Germany
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Cabelof AC, Carta V, Chen C, Pink M, Caulton KG. Pincers with diverse donors and their interconversion: application to Ni(II). Z Anorg Allg Chem 2021. [DOI: 10.1002/zaac.202100064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Alyssa C. Cabelof
- Department of Chemistry Indiana University 800 E. Kirkwood Ave. Bloomington IN, 47401 USA
| | - Veronica Carta
- Department of Chemistry Indiana University 800 E. Kirkwood Ave. Bloomington IN, 47401 USA
| | - Chun‐Hsing Chen
- Department of Chemistry Indiana University 800 E. Kirkwood Ave. Bloomington IN, 47401 USA
| | - Maren Pink
- Department of Chemistry Indiana University 800 E. Kirkwood Ave. Bloomington IN, 47401 USA
| | - Kenneth G. Caulton
- Department of Chemistry Indiana University 800 E. Kirkwood Ave. Bloomington IN, 47401 USA
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Cabelof AC, Carta V, Caulton KG. A proton-responsive ligand becomes a dimetal linker for multisubstrate assembly via nitrate deoxygenation. Chem Commun (Camb) 2021; 57:2780-2783. [PMID: 33598673 DOI: 10.1039/d0cc07886g] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A bidentate pyrazolylpyridine ligand (HL) was installed on divalent nickel to give [(HL)2Ni(NO3)]NO3. This compound reacts with a bis-silylated heterocycle, 1,4-bis-(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene (TMS2Pz) to simultaneously reduce one of the nitrate ligands and deprotonate one of the HL ligands, giving octahedral (HL)(L-)Ni(NO3). The mononitrate species formed is then further reacted with TMS2Pz to doubly deoxygenate nitrate and form [(L-)Ni(NO)]2, dimeric via bridging pyrazolate with bent nitrosyl ligands, representing a two-electron reduction of coordinated nitrate. Independent synthesis of a dimeric species [(L-)Ni(Br)]2 is reported and effectively assembles two metals with better atom economy.
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Affiliation(s)
- Alyssa C Cabelof
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, IN 47401, USA.
| | - Veronica Carta
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, IN 47401, USA.
| | - Kenneth G Caulton
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, IN 47401, USA.
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Beagan DM, Cabelof AC, Caulton KG. Back donation, intramolecular electron transfer and N-O bond scission targeting nitrogen oxyanion reduction: how can a metal complex assist? Dalton Trans 2021; 50:2149-2157. [PMID: 33491695 DOI: 10.1039/d0dt03430d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A density functional theory exploration studies a range of ancillary coordinated ligands accompanying nitrogen oxyanions with the goal of promoting back donation towards varied nitrogen oxidation states. Evaluation of a suite of Ru and Rh metal complexes reveals minimum back donation to the κ1-nitrogen oxyanion ligand, even upon one-electron reduction. This reveals some surprising consequences of reduction, including redox activity at pyridine and nitrogen oxyanion dissociation. Bidentate nitrate was therefore considered, where ancillary ligands enforce geometries that maximize M-NOx orbital overlap. This strategy is successful and leads to full electron transfer in several cases to form a pyramidal radical NO32- ligand. The impact of ancillary ligand on degree of nitrate reduction is probed by comparing the powerful o-donor tris-carbene borate (TCB) to a milder donor, tris-pyrazolyl borate (Tp). This reveals that with the milder Tp donor, nitrate reduction is only seen upon addition of a Lewis base. Protonation of neutral and anionic (TCB)Ru(κ2-NO3) at both terminal and internal oxygens reveals exergonic N-O bond cleavage for the reduced species, with one electron coming from Ru, yielding a RuIII hydroxide product. Comparison of H+ to Na+ electrophile shows weaker progress towards N-O bond scission. Finally, calculations on (TCB)Fe(κ2-NO3) and [(TCB)Fe(κ2-NO3)]- show that electron transfer to nitrate is possible even with an earth abundant 3d metal.
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Affiliation(s)
- Daniel M Beagan
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, IN 47401, USA.
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Cabelof AC, Erny AM, Carta V, Pink M, Caulton KG. Anion metathesis and chlorination of late transition metal pincer complexes: Comparing Co, Rh and Zn. Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2020.120118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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