1
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Konsewicz K, Laczkó G, Pápai I, Zhivonitko VV. Activation of H 2 using ansa-aminoboranes: solvent effects, dynamics, and spin hyperpolarization. Phys Chem Chem Phys 2024; 26:3197-3207. [PMID: 38193236 DOI: 10.1039/d3cp05816f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
Spin hyperpolarization generated upon activation of parahydrogen, the spin-0 isomer of H2, by ansa-aminoboranes (AABs) constitutes a rare but interesting example of applied metal-free catalysis in parahydrogen-induced polarization (PHIP). AAB molecular moieties made of light elements would be useful in important areas of NMR, such as chemosensing and the production of hyperpolarized substances, or generally in NMR sensitivity enhancement. At the same time, little is known about the detailed mechanistic aspects of underlying chemical processes. Herein, we present a joint experimental-computational study of the kinetic and thermodynamic aspects of H2 activation by AABs, for the first time providing molecular-level details and results of PHIP experiments with AABs in various solvents. Specifically, a large number of kinetic and thermodynamic parameters are measured experimentally for H2 activation by 2-aminophenylboranes of variable steric bulkiness of the boryl site. A clear correlation between the experimental and DFT-predicted thermochemical parameters is observed. PHIP effects in toluene, dichloromethane, and acetonitrile are characterized and rationalized based on the use of the kinetic and nuclear spin relaxation parameters. Altogether, the obtained results provide valuable information for the further rational design of efficient AAB catalysts for metal-free PHIP based on frustrated Lewis pair (FLP) chemistry.
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Affiliation(s)
- Karolina Konsewicz
- NMR Research Unit, Faculty of Science, University of Oulu, P.O. Box 3000, Oulu, 90014, Finland.
| | - Gergely Laczkó
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar Tudósok Körútja 2, H-1117 Budapest, Hungary
- Hevesy György PhD School of Chemistry, Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
| | - Imre Pápai
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar Tudósok Körútja 2, H-1117 Budapest, Hungary
| | - Vladimir V Zhivonitko
- NMR Research Unit, Faculty of Science, University of Oulu, P.O. Box 3000, Oulu, 90014, Finland.
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2
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Eills J, Budker D, Cavagnero S, Chekmenev EY, Elliott SJ, Jannin S, Lesage A, Matysik J, Meersmann T, Prisner T, Reimer JA, Yang H, Koptyug IV. Spin Hyperpolarization in Modern Magnetic Resonance. Chem Rev 2023; 123:1417-1551. [PMID: 36701528 PMCID: PMC9951229 DOI: 10.1021/acs.chemrev.2c00534] [Citation(s) in RCA: 45] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Magnetic resonance techniques are successfully utilized in a broad range of scientific disciplines and in various practical applications, with medical magnetic resonance imaging being the most widely known example. Currently, both fundamental and applied magnetic resonance are enjoying a major boost owing to the rapidly developing field of spin hyperpolarization. Hyperpolarization techniques are able to enhance signal intensities in magnetic resonance by several orders of magnitude, and thus to largely overcome its major disadvantage of relatively low sensitivity. This provides new impetus for existing applications of magnetic resonance and opens the gates to exciting new possibilities. In this review, we provide a unified picture of the many methods and techniques that fall under the umbrella term "hyperpolarization" but are currently seldom perceived as integral parts of the same field. Specifically, before delving into the individual techniques, we provide a detailed analysis of the underlying principles of spin hyperpolarization. We attempt to uncover and classify the origins of hyperpolarization, to establish its sources and the specific mechanisms that enable the flow of polarization from a source to the target spins. We then give a more detailed analysis of individual hyperpolarization techniques: the mechanisms by which they work, fundamental and technical requirements, characteristic applications, unresolved issues, and possible future directions. We are seeing a continuous growth of activity in the field of spin hyperpolarization, and we expect the field to flourish as new and improved hyperpolarization techniques are implemented. Some key areas for development are in prolonging polarization lifetimes, making hyperpolarization techniques more generally applicable to chemical/biological systems, reducing the technical and equipment requirements, and creating more efficient excitation and detection schemes. We hope this review will facilitate the sharing of knowledge between subfields within the broad topic of hyperpolarization, to help overcome existing challenges in magnetic resonance and enable novel applications.
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Affiliation(s)
- James Eills
- Institute
for Bioengineering of Catalonia, Barcelona
Institute of Science and Technology, 08028Barcelona, Spain,
| | - Dmitry Budker
- Johannes
Gutenberg-Universität Mainz, 55128Mainz, Germany,Helmholtz-Institut,
GSI Helmholtzzentrum für Schwerionenforschung, 55128Mainz, Germany,Department
of Physics, UC Berkeley, Berkeley, California94720, United States
| | - Silvia Cavagnero
- Department
of Chemistry, University of Wisconsin, Madison, Madison, Wisconsin53706, United States
| | - Eduard Y. Chekmenev
- Department
of Chemistry, Integrative Biosciences (IBio), Karmanos Cancer Institute
(KCI), Wayne State University, Detroit, Michigan48202, United States,Russian
Academy of Sciences, Moscow119991, Russia
| | - Stuart J. Elliott
- Molecular
Sciences Research Hub, Imperial College
London, LondonW12 0BZ, United Kingdom
| | - Sami Jannin
- Centre
de RMN à Hauts Champs de Lyon, Université
de Lyon, CNRS, ENS Lyon, Université Lyon 1, 69100Villeurbanne, France
| | - Anne Lesage
- Centre
de RMN à Hauts Champs de Lyon, Université
de Lyon, CNRS, ENS Lyon, Université Lyon 1, 69100Villeurbanne, France
| | - Jörg Matysik
- Institut
für Analytische Chemie, Universität
Leipzig, Linnéstr. 3, 04103Leipzig, Germany
| | - Thomas Meersmann
- Sir
Peter Mansfield Imaging Centre, University Park, School of Medicine, University of Nottingham, NottinghamNG7 2RD, United Kingdom
| | - Thomas Prisner
- Institute
of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic
Resonance, Goethe University Frankfurt, , 60438Frankfurt
am Main, Germany
| | - Jeffrey A. Reimer
- Department
of Chemical and Biomolecular Engineering, UC Berkeley, and Materials Science Division, Lawrence Berkeley National
Laboratory, Berkeley, California94720, United States
| | - Hanming Yang
- Department
of Chemistry, University of Wisconsin, Madison, Madison, Wisconsin53706, United States
| | - Igor V. Koptyug
- International Tomography Center, Siberian
Branch of the Russian Academy
of Sciences, 630090Novosibirsk, Russia,
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3
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Sorochkina K, Chernichenko K, Zhivonitko VV, Nieger M, Repo T. Water Reduction and Dihydrogen Addition in Aqueous Conditions With ansa-Phosphinoborane. Chemistry 2022; 28:e202201927. [PMID: 35861909 PMCID: PMC9804508 DOI: 10.1002/chem.202201927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Indexed: 01/05/2023]
Abstract
Ortho-phenylene-bridged phosphinoborane (2,6-Cl2 Ph)2 B-C6 H4 -PCy2 1 was synthesized in three steps from commercially available starting materials. 1 reacts with H2 or H2 O under mild conditions to form corresponding zwitterionic phosphonium borates 1-H2 or 1-H2 O. NMR studies revealed both reactions to be remarkably reversible. Thus, when exposed to H2 , 1-H2 O partially converts to 1-H2 even in the presence of multiple equivalents of water in the solution. The addition of parahydrogen to 1 leads to nuclear spin hyperpolarization both in dry and hydrous solvents, confirming the dissociation of 1-H2 O to free 1. These observations were supported by computational studies indicating that the formation of 1-H2 and 1-H2 O from 1 are thermodynamically favored. Unexpectedly, 1-H2 O can release molecular hydrogen to form phosphine oxide 1-O. Kinetic, mechanistic, and computational (DFT) studies were used to elucidate the unique "umpolung" water reduction mechanism.
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Affiliation(s)
- Kristina Sorochkina
- Department of ChemistryUniversity of HelsinkiA. I. Virtasen aukio 100014HelsinkiFinland
| | - Konstantin Chernichenko
- Department of ChemistryUniversity of HelsinkiA. I. Virtasen aukio 100014HelsinkiFinland,Chemical Process Research and Development Janssen PharmaceuticaTurnhoutseweg 302340BeerseBelgium
| | | | - Martin Nieger
- Department of ChemistryUniversity of HelsinkiA. I. Virtasen aukio 100014HelsinkiFinland
| | - Timo Repo
- Department of ChemistryUniversity of HelsinkiA. I. Virtasen aukio 100014HelsinkiFinland
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4
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Tickner BJ, Zhivonitko VV. Advancing homogeneous catalysis for parahydrogen-derived hyperpolarisation and its NMR applications. Chem Sci 2022; 13:4670-4696. [PMID: 35655870 PMCID: PMC9067625 DOI: 10.1039/d2sc00737a] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 03/21/2022] [Indexed: 12/18/2022] Open
Abstract
Parahydrogen-induced polarisation (PHIP) is a nuclear spin hyperpolarisation technique employed to enhance NMR signals for a wide range of molecules. This is achieved by exploiting the chemical reactions of parahydrogen (para-H2), the spin-0 isomer of H2. These reactions break the molecular symmetry of para-H2 in a way that can produce dramatically enhanced NMR signals for reaction products, and are usually catalysed by a transition metal complex. In this review, we discuss recent advances in novel homogeneous catalysts that can produce hyperpolarised products upon reaction with para-H2. We also discuss hyperpolarisation attained in reversible reactions (termed signal amplification by reversible exchange, SABRE) and focus on catalyst developments in recent years that have allowed hyperpolarisation of a wider range of target molecules. In particular, recent examples of novel ruthenium catalysts for trans and geminal hydrogenation, metal-free catalysts, iridium sulfoxide-containing SABRE systems, and cobalt complexes for PHIP and SABRE are reviewed. Advances in this catalysis have expanded the types of molecules amenable to hyperpolarisation using PHIP and SABRE, and their applications in NMR reaction monitoring, mechanistic elucidation, biomedical imaging, and many other areas, are increasing.
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Affiliation(s)
- Ben J Tickner
- NMR Research Unit, Faculty of Science, University of Oulu P.O. Box 3000 Oulu 90014 Finland
- Department of Chemical and Biological Physics, Faculty of Chemistry, Weizmann Institute of Science Rehovot 7610001 Israel
| | - Vladimir V Zhivonitko
- NMR Research Unit, Faculty of Science, University of Oulu P.O. Box 3000 Oulu 90014 Finland
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5
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Zakharov DO, Chernichenko K, Sorochkina K, Repo T, Zhivonitko VV. Parahydrogen-induced polarization study of imine hydrogenations mediated by a metal-free catalyst. Dalton Trans 2022; 51:13606-13611. [DOI: 10.1039/d2dt02178a] [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
Parahydrogen-induced polarization is a nuclear spin hyperpolarization technique that can provide strongly enhanced NMR signals of catalytic hydrogenation reaction products and intermediates. Among other matters, this can be employed to...
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6
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Zakharov DO, Chernichenko K, Sorochkina K, Yang S, Telkki VV, Repo T, Zhivonitko VV. Parahydrogen-Induced Polarization in Hydrogenation Reactions Mediated by a Metal-Free Catalyst. Chemistry 2021; 28:e202103501. [PMID: 34928532 PMCID: PMC9303582 DOI: 10.1002/chem.202103501] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Indexed: 11/28/2022]
Abstract
We report nuclear spin hyperpolarization of various alkenes achieved in alkyne hydrogenations with parahydrogen over a metal‐free hydroborane catalyst (HCAT). Being an intramolecular frustrated Lewis pair aminoborane, HCAT utilizes a non‐pairwise mechanism of H2 transfer to alkynes that normally prevents parahydrogen‐induced polarization (PHIP) from being observed. Nevertheless, the specific spin dynamics in catalytic intermediates leads to the hyperpolarization of predominantly one hydrogen in alkene. PHIP enabled the detection of important HCAT‐alkyne‐H2 intermediates through substantial 1H, 11B and 15N signal enhancement and allowed advanced characterization of the catalytic process.
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Affiliation(s)
| | | | - Kristina Sorochkina
- University of Helsinki: Helsingin Yliopisto, Department of Chemistry, FINLAND
| | - Shengjun Yang
- University of Oulu: Oulun Yliopisto, NMR Research Unit, FINLAND
| | | | - Timo Repo
- University of Helsinki: Helsingin Yliopisto, Department of Chemistry, FINLAND
| | - Vladimir V Zhivonitko
- University of Oulu: Oulun Yliopisto, NMR Research Unit, Pentti Kaiteral Katu 1, 90570, Oulu, FINLAND
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7
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Zhivonitko VV, Beer H, Zakharov DO, Bresien J, Schulz A. Hyperpolarization Effects in Parahydrogen Activation with Pnictogen Biradicaloids: Metal-free PHIP and SABRE. Chemphyschem 2021; 22:813-817. [PMID: 33725397 PMCID: PMC8251785 DOI: 10.1002/cphc.202100141] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 03/11/2021] [Indexed: 01/30/2023]
Abstract
Biradicaloids attract attention as a novel class of reagents that can activate small molecules such as H2, ethylene and CO2. Herein, we study activation of parahydrogen (nuclear spin‐0 isomer of H2) by a number of 4‐ and 5‐membered pnictogen biradicaloids based on hetero‐cyclobutanediyl [X(μ‐NTer)2Z] and hetero‐cyclopentanediyl [X(μ‐NTer)2ZC(NDmp)] moieties (X,Z=P,As; Ter=2,6‐Mes2−C6H3, Dmp=2,6‐Me2−C6H3). The concerted mechanism of this reaction allowed observing strong nuclear spin hyperpolarization effects in 1H and 31P NMR experiments. Signal enhancements from two to four orders of magnitude were detected at 9.4 T depending on the structure. It is demonstrated that 4‐membered biradicaloids activate H2 reversibly, leading to SABRE (signal amplification by reversible exchange) hyperpolarization of biradicaloids themselves and their H2 adducts. In contrast, the 5‐membered counterparts demonstrate rather irreversible parahydrogen activation resulting in hyperpolarized H2 adducts only. Kinetic measurements provided parameters to support experimental observations.
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Affiliation(s)
| | - Henrik Beer
- Institute of Chemistry, University of Rostock, Albert-Einstein-Strasse 3a, 18059, Rostock, Germany
| | - Danila O Zakharov
- NMR Research Unit, University of Oulu, P.O. Box 3000, 90014, Oulu, Finland
| | - Jonas Bresien
- Institute of Chemistry, University of Rostock, Albert-Einstein-Strasse 3a, 18059, Rostock, Germany
| | - Axel Schulz
- Institute of Chemistry, University of Rostock, Albert-Einstein-Strasse 3a, 18059, Rostock, Germany.,Leibniz-Institut für Katalyse e.V., Universität Rostock, Albert-Einstein-Strasse 29a, 18059, Rostock, Germany
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8
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Holtkamp P, Schwabedissen J, Neumann B, Stammler HG, Koptyug IV, Zhivonitko VV, Mitzel NW. A Zwitterionic Phosphonium Stannate(II) via Hydrogen Splitting by a Sn/P Frustrated Lewis-Pair and Reductive Elimination. Chemistry 2020; 26:17381-17385. [PMID: 33016507 PMCID: PMC7839681 DOI: 10.1002/chem.202004425] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Indexed: 11/22/2022]
Abstract
The reactivity of the frustrated Lewis pair (FLP) (F5C2)3SnCH2P(tBu)2 (1) was investigated with respect to the activation of elemental hydrogen. The reaction of 1 at elevated hydrogen pressure afforded the intramolecular phosphonium stannate(II) (F5C2)2SnCH2PH(tBu)2 (3). It was characterized by means of multinuclear NMR spectroscopy and single crystal X‐ray diffraction. NMR experiments with the two isotopologues H2 and D2 showed it to be formed via an H2 adduct (F5C2)3HSnCH2PH(tBu)2 (2) and the subsequent formal reductive elimination of pentafluoroethane; this is supported by DFT calculations. Parahydrogen‐induced polarization experiments revealed the formation of a second product of the reaction of 1 with H2, [HP(tBu)2Me][Sn(C2F5)3] (4), in 1H NMR spectra, whereas 2 was not detected due to its transient nature.
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Affiliation(s)
- Philipp Holtkamp
- Lehrstuhl für Anorganische Chemie und Strukturchemie, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Jan Schwabedissen
- Lehrstuhl für Anorganische Chemie und Strukturchemie, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Beate Neumann
- Lehrstuhl für Anorganische Chemie und Strukturchemie, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Hans-Georg Stammler
- Lehrstuhl für Anorganische Chemie und Strukturchemie, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Igor V Koptyug
- International Tomography Center, SB RAS, Institutskaya St. 3A, Novosibirsk, 630090, Russia
| | | | - Norbert W Mitzel
- Lehrstuhl für Anorganische Chemie und Strukturchemie, Fakultät für Chemie, Universität Bielefeld, Universitätsstraße 25, 33615, Bielefeld, Germany
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9
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Tickner BJ, Rayner PJ, Duckett SB. Using SABRE Hyperpolarized 13C NMR Spectroscopy to Interrogate Organic Transformations of Pyruvate. Anal Chem 2020; 92:9095-9103. [DOI: 10.1021/acs.analchem.0c01334] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Ben. J. Tickner
- Center for Hyperpolarization in Magnetic Resonance (CHyM), Department of Chemistry, University of York, Heslington, York YO10 5NY, United Kingdom
| | - Peter J. Rayner
- Center for Hyperpolarization in Magnetic Resonance (CHyM), Department of Chemistry, University of York, Heslington, York YO10 5NY, United Kingdom
| | - Simon B. Duckett
- Center for Hyperpolarization in Magnetic Resonance (CHyM), Department of Chemistry, University of York, Heslington, York YO10 5NY, United Kingdom
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10
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Berthault P, Boutin C, Martineau-Corcos C, Carret G. Use of dissolved hyperpolarized species in NMR: Practical considerations. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2020; 118-119:74-90. [PMID: 32883450 DOI: 10.1016/j.pnmrs.2020.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 03/20/2020] [Accepted: 03/20/2020] [Indexed: 06/11/2023]
Abstract
Hyperpolarization techniques that can transiently boost nuclear spin polarization are generally carried out at low temperature - as in the case of dynamic nuclear polarization - or at high temperature in the gaseous state - as in the case of optically pumped noble gases. This review aims at describing the various issues and challenges that have been encountered during dissolution of hyperpolarized species, and solutions to these problems that have been or are currently proposed in the literature. During the transport of molecules from the polarizer to the NMR detection region, and when the hyperpolarized species or a precursor of hyperpolarization (e.g. parahydrogen) is introduced into the solution of interest, several obstacles need to be overcome to keep a high level of final magnetization. The choice of the magnetic field, the design of the dissolution setup, and ways to isolate hyperpolarized compounds from relaxation agents will be presented. Due to the non-equilibrium character of the hyperpolarization, new NMR pulse sequences that perform better than the classical ones will be described. Finally, three applications in the field of biology will be briefly mentioned.
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Affiliation(s)
- Patrick Berthault
- NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette, France.
| | - Céline Boutin
- NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette, France
| | - Charlotte Martineau-Corcos
- ILV, UMR CNRS 8180, Université de Versailles Saint Quentin, 45 avenue des Etats-Unis, 78035 Versailles Cedex, France
| | - Guillaume Carret
- Cortecnet, 15 rue des tilleuls, 78960 Voisins-le-Bretonneux, France
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11
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Tickner BJ, Parker RR, Whitwood AC, Duckett SB. Probing the Hydrogenation of Vinyl Sulfoxides Using para-Hydrogen. Organometallics 2019; 38:4377-4382. [PMID: 31787798 PMCID: PMC6880776 DOI: 10.1021/acs.organomet.9b00610] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Indexed: 12/25/2022]
Abstract
![]()
Vinyl sulfoxides are an important functional group used
in a wide range of organic transformations. Here, we use [IrCl(COD)(IMes)]
where IMes = 1,3-bis(2,4,6-trimethyl-phenyl)imidazole-2-ylidene and
COD = cis,cis-1,5-cyclooctadiene
to rapidly hydrogenate phenylvinylsulfoxide. We use para-hydrogen-induced hyperpolarization (PHIP) to follow this reaction
with [IrCl(H)2(IMes)(S(O)(Ph)(Et))2] dominating
in the later stages. Decomposition to form the reduced C–S
bond cleavage product [Ir2(H)3(κ2-H)(κ2-SPh)2(IMes)2(S(Et)(Ph)O)]
limits turnover. The related product [Ir2(H)4(κ2-S)(IMes)2(S(O)(CH2Ph)2)2] is formed from dibenzylsulfoxide, demonstrating
the wider utility of this transformation.
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Affiliation(s)
- Ben J Tickner
- Center for Hyperpolarisation in Magnetic Resonance (CHyM), University of York, Heslington, York YO10 5NY, United Kingdom
| | - Rachel R Parker
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Adrian C Whitwood
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Simon B Duckett
- Center for Hyperpolarisation in Magnetic Resonance (CHyM), University of York, Heslington, York YO10 5NY, United Kingdom
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12
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Tickner BJ, Lewis JS, John RO, Whitwood AC, Duckett SB. Mechanistic insight into novel sulfoxide containing SABRE polarisation transfer catalysts. Dalton Trans 2019; 48:15198-15206. [PMID: 31576870 DOI: 10.1039/c9dt02951f] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Signal Amplification By Reversible Exchange (SABRE) is a hyperpolarisation technique that commonly uses [Ir(H)2(carbene)(substrate)3]Cl complexes to catalytically transfer magnetisation from para-hydrogen derived hydride ligands to coordinated substrates. Here, we explore the reactivity of a novel class of such catalysts based on sulfoxide containing [IrCl(H)2(carbene)(DMSO)2], which are involved in the hyperpolarisation of pyruvate using SABRE. We probe the reactivity of this species by NMR and DFT and upon reaction with sodium pyruvate establish the formation of two isomers of [Ir(H)2(η2-pyruvate)(DMSO)(IMes)]. Studies with related disodium oxalate yield [Ir2(H)4(IMes)2(DMSO)2(η2-κ2-Oxalate)] that is characterised by NMR and X-ray diffraction.
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Affiliation(s)
- Ben J Tickner
- Center for Hyperpolarization in Magnetic Resonance (CHyM), University of York, Heslington, York YO10 5NY, UK.
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13
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Zhivonitko VV, Bresien J, Schulz A, Koptyug IV. Parahydrogen-induced polarization with a metal-free P-P biradicaloid. Phys Chem Chem Phys 2019; 21:5890-5893. [PMID: 30694276 PMCID: PMC6430094 DOI: 10.1039/c8cp07625a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Metal-free H2 activations are unusual but interesting for catalytic transformations, particularly in parahydrogen-based nuclear spin hyperpolarization techniques. We demonstrate that metal-free singlet phosphorus biradicaloid, [P(μ-NTer)]2, provides pronounced 1H and 31P hyperpolarization while activating the parahydrogen molecules. A brief analysis of the resulting NMR signals and the important kinetic parameters are presented.
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