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Neshat A, Mousavizadeh Mobarakeh A, Yousefshahi MR, Varmaghani F, Dusek M, Eigner V, Kucerakova M. Introducing Novel Redox-Active Bis(phenolate) N-Heterocyclic Carbene Proligands: Investigation of Their Coordination to Fe(II)/Fe(III) and Their Catalytic Activity in Transfer Hydrogenation of Carbonyl Compounds. ACS OMEGA 2024; 9:25135-25145. [PMID: 38882110 PMCID: PMC11170717 DOI: 10.1021/acsomega.4c02602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 05/19/2024] [Accepted: 05/23/2024] [Indexed: 06/18/2024]
Abstract
A simple and efficient procedure for synthesizing novel pincer-type tridentate N-heterocyclic carbene bisphenolate ligands is reported. The synthesis of pincer proligands with N,N'-disubstituted imidazoline core, 5 and 6, was carried out via triethylorthoformate-promoted cyclization of either N,N'-bis(2-hydroxy-3,5-di-tert-butylphenyl)cyclohexanediamine, 3, or N,N'-bis(2-hydroxyphenyl)cyclohexanediamine, 4, in the presence of concentrated hydrochloric acid. Cyclic voltammograms of the ligands revealed ligand-centered redox activity, indicating the noninnocent nature of the ligands. The voltammograms of the ligands exhibit two successive one-electron oxidations and two consecutive one-electron reductions. In contrast to previous reports, the redox-active ligands in this study exhibit one-electron oxidation and reduction processes. All products were thoroughly characterized by using 1H and 13C NMR spectroscopy. The base-promoted deprotonation of the proligands and subsequent reaction with iron(II) and iron(III) chlorides yielded compounds 7 and 8. These compounds are binuclear and tetranuclear iron(III) complexes that do not contain carbene functional groups. Complexes 7 and 8 were characterized by using elemental analysis and single-crystal X-ray crystallography. At low catalyst loadings, both 7 and 8 exhibited high catalytic activity in the transfer hydrogenation of selected aldehydes and ketones.
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Affiliation(s)
- Abdollah Neshat
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), 444 Prof. Sobouti Blvd., Gava Zang, Zanjan 45137-66731, Iran
| | - Ali Mousavizadeh Mobarakeh
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), 444 Prof. Sobouti Blvd., Gava Zang, Zanjan 45137-66731, Iran
| | - Mohammad Reza Yousefshahi
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), 444 Prof. Sobouti Blvd., Gava Zang, Zanjan 45137-66731, Iran
| | - Fahimeh Varmaghani
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), 444 Prof. Sobouti Blvd., Gava Zang, Zanjan 45137-66731, Iran
| | - Michal Dusek
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Prague 8, The Czech Republic
| | - Vaclav Eigner
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Prague 8, The Czech Republic
| | - Monika Kucerakova
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Prague 8, The Czech Republic
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Kevlishvili I, Duan C, Kulik HJ. Classification of Hemilabile Ligands Using Machine Learning. J Phys Chem Lett 2023:11100-11109. [PMID: 38051982 DOI: 10.1021/acs.jpclett.3c02828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Hemilabile ligands have the capacity to partially disengage from a metal center, providing a strategy to balance stability and reactivity in catalysis, but they are not straightforward to identify. We identify ligands in the Cambridge Structural Database that have been crystallized with distinct denticities and are thus identifiable as hemilabile ligands. We implement a semi-supervised learning approach using a label-spreading algorithm to augment a small negative set that is supported by heuristic rules of ligand and metal co-occurrence. We show that a heuristic based on coordinating atom identity alone is not sufficient to identify whether a ligand is hemilabile, and our trained machine-learning classification models are instead needed to predict whether a bi-, tri-, or tetradentate ligand is hemilabile with high accuracy and precision. Feature importance analysis of our models shows that the second, third, and fourth coordination spheres all play important roles in ligand hemilability.
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Affiliation(s)
- Ilia Kevlishvili
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Chenru Duan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Wei D, Shi X, Junge H, Du C, Beller M. Carbon neutral hydrogen storage and release cycles based on dual-functional roles of formamides. Nat Commun 2023; 14:3726. [PMID: 37349304 DOI: 10.1038/s41467-023-39309-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 06/07/2023] [Indexed: 06/24/2023] Open
Abstract
The development of alternative clean energy carriers is a key challenge for our society. Carbon-based hydrogen storage materials are well-suited to undergo reversible (de)hydrogenation reactions and the development of catalysts for the individual process steps is crucial. In the current state, noble metal-based catalysts still dominate this field. Here, a system for partially reversible and carbon-neutral hydrogen storage and release is reported. It is based on the dual-functional roles of formamides and uses a small molecule Fe-pincer complex as the catalyst, showing good stability and reusability with high productivity. Starting from formamides, quantitative production of CO-free hydrogen is achieved at high selectivity ( > 99.9%). This system works at modest temperatures of 90 °C, which can be easily supplied by the waste heat from e.g., proton-exchange membrane fuel cells. Employing such system, we achieve >70% H2 evolution efficiency and >99% H2 selectivity in 10 charge-discharge cycles, avoiding undesired carbon emission between cycles.
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Affiliation(s)
- Duo Wei
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, P. R. China
- Leibniz-Institut für Katalyse e.V, 18059, Rostock, Germany
| | - Xinzhe Shi
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, P. R. China
- Leibniz-Institut für Katalyse e.V, 18059, Rostock, Germany
| | - Henrik Junge
- Leibniz-Institut für Katalyse e.V, 18059, Rostock, Germany.
| | - Chunyu Du
- School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, P. R. China.
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Hert CM, Curley JB, Kelley SP, Hazari N, Bernskoetter WH. Comparative CO 2 Hydrogenation Catalysis with MACHO-type Manganese Complexes. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Clayton M. Hert
- The Department of Chemistry, The University of Missouri, Columbia, Missouri 65211, United States
| | - Julia B. Curley
- The Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Steven P. Kelley
- The Department of Chemistry, The University of Missouri, Columbia, Missouri 65211, United States
| | - Nilay Hazari
- The Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States
| | - Wesley H. Bernskoetter
- The Department of Chemistry, The University of Missouri, Columbia, Missouri 65211, United States
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Smith MB. The Backbone of Success of P,N-Hybrid Ligands: Some Recent Developments. Molecules 2022; 27:6293. [PMID: 36234830 PMCID: PMC9614609 DOI: 10.3390/molecules27196293] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 09/21/2022] [Accepted: 09/21/2022] [Indexed: 12/03/2022] Open
Abstract
Organophosphorus ligands are an invaluable family of compounds that continue to underpin important roles in disciplines such as coordination chemistry and catalysis. Their success can routinely be traced back to facile tuneability thus enabling a high degree of control over, for example, electronic and steric properties. Diphosphines, phosphorus compounds bearing two separated PIII donor atoms, are also highly valued and impart their own unique features, for example excellent chelating properties upon metal complexation. In many classical ligands of this type, the backbone connectivity has been based on all carbon spacers only but there is growing interest in embedding other donor atoms such as additional nitrogen (-NH-, -NR-) sites. This review will collate some important examples of ligands in this field, illustrate their role as ligands in coordination chemistry and highlight some of their reactivities and applications. It will be shown that incorporation of a nitrogen-based group can impart unusual reactivities and important catalytic applications.
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Affiliation(s)
- Martin B Smith
- Department of Chemistry, Loughborough University, Loughborough, Leics LE11 3TU, UK
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Pandey B, Krause JA, Guan H. Iron Dihydride Complex Stabilized by an All-Phosphorus-Based Pincer Ligand and Carbon Monoxide. Inorg Chem 2022; 61:11143-11155. [PMID: 35816559 DOI: 10.1021/acs.inorgchem.2c01027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PNP-pincer-stabilized iron carbonyl dihydride complexes are key intermediates in catalytic hydrogenation and dehydrogenation reactions; however, decomposition through these intermediates has been observed. This inspires the development of a PPP-pincer system that may show improved catalyst stability. In this work, bis[2-(diisopropylphosphino)phenyl]phosphine (or iPrPPHP) is used to react with FeCl2 under a carbon monoxide (CO) atmosphere to yield trans-(iPrPPHP)Fe(CO)Cl2. A subsequent reaction with NaBH4 produces syn/anti-(iPrPPHP)FeH(CO)Cl or cis,anti-(iPrPPHP)Fe(CO)H2, depending on the amount of NaBH4 employed. The cis-dihydride complex shows catalytic activity for the conversion of PhCHO to PhCH2OH (under H2) or PhCO2CH2Ph (under Ar). It also catalyzes the dehydrogenation of PhCH2OH to PhCHO and PhCO2CH2Ph, albeit with limited turnover numbers. A more efficient catalytic process is the dehydrogenation of formic acid to carbon dioxide (CO2), which can operate under additive-free conditions. Mechanistic investigation suggests that the cis-dihydride complex undergoes protonation with formic acid to release H2 while forming anti-(iPrPPHP)FeH(CO)(OCHO)·HCO2H, in which the CO ligand has shifted and the formate is hydrogen-bonded to formic acid. The hydrido formate complex loses CO2 under ambient conditions, completing the catalytic cycle by reforming the cis-dihydride complex.
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Affiliation(s)
- Bedraj Pandey
- Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States
| | - Jeanette A Krause
- Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States
| | - Hairong Guan
- Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States
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Wu T, Wang S, Lv Y, Fu T, Jiang J, Lu X, Yu ZP, zhang J, Wang L, Zhou HP. A New Bis(thioether)-Dipyrrin N2S2 Ligand and Its Coordination Behaviors to Nickel, Copper and Zinc. Dalton Trans 2022; 51:9699-9707. [DOI: 10.1039/d2dt01282k] [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
Tetradentate N2S2 coordination platforms are widespread in biological system and have endowed the metalloenzymes and metalloproteins with abundant reactivities and functions. However, there have only three types of N2S2 scaffolds...
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