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Chaloupecká E, Kurfiřt M, Červenková Šťastná L, Karban J, Dračínský M. Exploring long-range fluorine-carbon J-coupling for conformational analysis of deoxyfluorinated disaccharides: A combined computational and NMR study. Bioorg Chem 2024; 147:107388. [PMID: 38678775 DOI: 10.1016/j.bioorg.2024.107388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 04/18/2024] [Accepted: 04/18/2024] [Indexed: 05/01/2024]
Abstract
In this study, we investigated the potential of long-range fluorine-carbon J-coupling for determining the structures of deoxyfluorinated disaccharides. Three disaccharides, previously synthesized as potential galectin inhibitors, exhibited through-space fluorine-carbon J-couplings. In our independent conformational analysis of these disaccharide derivatives, we employed a combination of density functional theory (DFT) calculations and nuclear magnetic resonance (NMR) experiments. By comparing the calculated nuclear shieldings with the experimental carbon chemical shifts, we were able to identify the most probable conformers for each compound. A model comprising fluoromethane and methane molecules was used to study the relationship between molecular arrangements and intermolecular through-space J-coupling. Our study demonstrates the important effect of internuclear distance and molecular orientation on the magnitude of fluorine-carbon coupling. The experimental values for the fluorine-carbon through-space couplings (TSCs) of the disaccharides corresponded with values calculated for the most probable conformers identified by the conformational analysis. These results unlock the broader application of fluorine-carbon TSCs as powerful tools for conformational analysis of flexible molecules, offering valuable insights for future structural investigations.
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Affiliation(s)
- Ema Chaloupecká
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 160 00 Prague, Czech Republic; Department of Organic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, 128 40 Prague 2, Czech Republic
| | - Martin Kurfiřt
- Institute of Chemical Process Fundamentals of the Czech Academy of Sciences, Rozvojová 1/135, 165 00 Prague 6, Czech Republic; University of Chemistry and Technology, Technická 3, 166 28 Prague 6, Czech Republic
| | - Lucie Červenková Šťastná
- Institute of Chemical Process Fundamentals of the Czech Academy of Sciences, Rozvojová 1/135, 165 00 Prague 6, Czech Republic
| | - Jindřich Karban
- Institute of Chemical Process Fundamentals of the Czech Academy of Sciences, Rozvojová 1/135, 165 00 Prague 6, Czech Republic
| | - Martin Dračínský
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, 160 00 Prague, Czech Republic.
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2
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Chiari C, Batista PR, Viesser RV, Schenberg LA, Ducati LC, Linclau B, Tormena CF. Molecular dynamics and NMR reveal the coexistence of H-bond-assisted and through-space JFH coupling in fluorinated amino alcohols. Org Biomol Chem 2024; 22:2580-2595. [PMID: 38441115 DOI: 10.1039/d4ob00049h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
The JFH coupling constants in fluorinated amino alcohols were investigated through experimental and theoretical approaches. The experimental JFH couplings were only reproduced theoretically when explicit solvation through molecular dynamics (MD) simulations was conducted in DMSO as the solvent. The combination of MD conformation sampling and DFT NMR spin-spin coupling calculations for these compounds reveals the simultaneous presence of through-space (TS) and hydrogen bond (H-bond) assisted JFH coupling between fluorine and hydrogen of the NH group. Furthermore, MD simulations indicate that the hydrogen in the amino group participates in both an intermolecular bifurcated H-bond with DMSO and in transmitting the observed JFH coupling. The contribution of TS to the JFH coupling is due to the spatial proximity of the fluorine and the NH group, aided by a combination of the non-bonding transmission pathway and the hydrogen bonding pathway. The experimental JFH coupling observed for the molecules studied should be represented as 4TS/1hJFH coupling.
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Affiliation(s)
- Cassia Chiari
- Institute of Chemistry, University of Campinas - UNICAMP, P. O. Box 6154, 13083-970, Campinas, São Paulo, Brazil.
| | - Patrick R Batista
- Institute of Chemistry, University of Campinas - UNICAMP, P. O. Box 6154, 13083-970, Campinas, São Paulo, Brazil.
| | - Renan V Viesser
- Department of Chemistry, University of Houston, Houston, TX 77024, USA
| | - Leonardo A Schenberg
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748, 05508-000, São Paulo, SP, Brazil
| | - Lucas C Ducati
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748, 05508-000, São Paulo, SP, Brazil
| | - Bruno Linclau
- Department of Organic and Macromolecular Chemistry, Ghent University, Ghent 9000, Belgium
| | - Cláudio F Tormena
- Institute of Chemistry, University of Campinas - UNICAMP, P. O. Box 6154, 13083-970, Campinas, São Paulo, Brazil.
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3
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Saielli G. Through-space scalar spin-spin coupling: from rigid intramolecular cases to short-lived van der Waals complexes. Chemphyschem 2024; 25:e202300963. [PMID: 38215244 DOI: 10.1002/cphc.202300963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/06/2024] [Accepted: 01/08/2024] [Indexed: 01/14/2024]
Abstract
We will discuss, with the help of few selected examples, how the concept of through-space scalar spin-spin coupling between non covalently bonded nuclei has evolved in recent years. We will first present systems where 'no covalent bond' actually means that the two atoms are separated by a large number of bonds; then we will see cases where it is referred to true van der Waals dimers, but with the two atoms somehow constrained in their positions; we will finish with the most recent examples of liquids and even gaseous mixtures with full translational degrees of freedom in a regime of intermolecular/interatomic fast exchange.
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Affiliation(s)
- Giacomo Saielli
- CNR Institute on Membrane Technology, Unit of Padova, Via Marzolo, 1, 35131, Padova, Italy
- Department of Chemical Sciences, University of Padova, Via Marzolo, 1, 35131, Padova, Italy
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4
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Cariello G, Zeoly LA, Piscelli BA, Lectka T, Cormanich RA. The pitfalls of using JHF spin-spin coupling constants to infer hydrogen bond formation in organofluorine compounds. Chem Commun (Camb) 2023. [PMID: 37987509 DOI: 10.1039/d3cc05389j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Theoretical decomposition of "through space" spin-spin coupling constants (SSCCs) in organofluorine compounds signal that intramolecular hydrogen bonds (H-bonds) are not the primary mechanism of transmission for SSCCs. Increasing solvent polarity may disrupt H-bonds, but not necessarily the JFH SSCC. Substituent effects may drastically alter the SSCC transmission pathway. Accurate SSCC analysis requires benchmarking theoretical calculations to support experimental data interpretation.
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Affiliation(s)
- Guilherme Cariello
- Universidade Estadual de Campinas (UNICAMP), Instituto de Química, Monteiro Lobato Street, Campinas, Sao Paulo 13083-862, Brazil.
| | - Lucas A Zeoly
- Universidade Estadual de Campinas (UNICAMP), Instituto de Química, Monteiro Lobato Street, Campinas, Sao Paulo 13083-862, Brazil.
| | - Bruno A Piscelli
- Universidade Estadual de Campinas (UNICAMP), Instituto de Química, Monteiro Lobato Street, Campinas, Sao Paulo 13083-862, Brazil.
| | - Thomas Lectka
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, MD, 21218, USA.
| | - Rodrigo A Cormanich
- Universidade Estadual de Campinas (UNICAMP), Instituto de Química, Monteiro Lobato Street, Campinas, Sao Paulo 13083-862, Brazil.
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5
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Rusakova IL, Rusakov YY, Krivdin LB. Computational 199 Hg NMR. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2022; 60:929-953. [PMID: 35737297 DOI: 10.1002/mrc.5296] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/20/2022] [Accepted: 06/21/2022] [Indexed: 06/15/2023]
Abstract
Theoretical background and fundamental results dealing with the computation of mercury chemical shifts and spin-spin coupling constants are reviewed with a special emphasis on their stereochemical behavior and applications.
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Affiliation(s)
- Irina L Rusakova
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
| | - Yuriy Yu Rusakov
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
| | - Leonid B Krivdin
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
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6
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Harry SA, Garrison NG, Zhu A, Xiang MR, Siegler MA, Lectka T. C-F Bonds as "Frozen" Nucleophiles: Unconsummated S N2 Reactions. J Org Chem 2022; 87:13406-13410. [PMID: 36166828 DOI: 10.1021/acs.joc.2c01788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this note, we present a series of rigid molecules that show close enforced interactions between Ar-F moieties and -CH2X groups in a "tetrel bond" configuration similar to a nascent SN2 attack. We explore the spectroscopic, crystallographic, and chemical reactivity consequences of these unusual interactions, including significant through-space spin-spin couplings, short C-F···CH2X distances, and differential SN1 and SN2 reaction pathways. We also reveal experimental evidence of carbon-based tetrel bonds influencing chemical reactivity in solution. Finally, density functional theory (DFT) calculations are employed throughout this study to confirm and illuminate our experimental data.
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Affiliation(s)
- Stefan Andrew Harry
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Nathaniel G Garrison
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Andrea Zhu
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Michael Richard Xiang
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Maxime A Siegler
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Thomas Lectka
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
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7
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Quantum Chemical Approaches to the Calculation of NMR Parameters: From Fundamentals to Recent Advances. MAGNETOCHEMISTRY 2022. [DOI: 10.3390/magnetochemistry8050050] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Quantum chemical methods for the calculation of indirect NMR spin–spin coupling constants and chemical shifts are always in progress. They never stay the same due to permanently developing computational facilities, which open new perspectives and create new challenges every now and then. This review starts from the fundamentals of the nonrelativistic and relativistic theory of nuclear magnetic resonance parameters, and gradually moves towards the discussion of the most popular common and newly developed methodologies for quantum chemical modeling of NMR spectra.
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8
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Soares JV, Dal Poggetto G, Viesser RV, Couto UR, Tormena CF. Stereoelectronic interactions: A booster for 4 J HF transmission. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2022; 60:481-488. [PMID: 35023222 DOI: 10.1002/mrc.5248] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 01/04/2022] [Accepted: 01/10/2022] [Indexed: 05/21/2023]
Abstract
Long-range proton-fluorine coupling constants (n JHF ) are helpful for the structure elucidation of fluorinated molecules. However, their magnitude and sign can change with the relative position of coupled nuclei and the presence of substituents. Here, trans-4-tert-butyl-2-fluorocyclohexanone was used as a model compound for the study of the transmission of 4 JHF . In this compound, the 4 JH6axF was measured to be +5.1 Hz, which is five times larger than the remaining 4 JHF in the same molecule (4 JH4F = +1.0 Hz and 4 JH6eqF = +1.0 Hz). Through a combination of experimental data, natural bond orbital (NBO) and natural J-coupling (NJC) analyses, we observed that stereoelectronic interactions involving the π system of the carbonyl group are involved in the transmission pathway for the 4 JH6axF . Interactions containing the π system as an electron acceptor (e.g., σC6H6ax → π*C═O and σCF → π*C═O ) increase the value of the 4 JH6axF , while the interaction of the π system as an electron donor (e.g., πC═O → σ*CF ) decreases it. Additionally, the carbonyl group was shown not to be part of the transmission pathway of the diequatorial 4 JH6eqF coupling in cis-4-tert-butyl-2-fluorocyclohexanone, revealing that there is a crucial symmetry requirement that must be fulfilled for the π system to influence the value of the 4 JHF in these systems.
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Affiliation(s)
- João Vitor Soares
- Institute of Chemistry, University of Campinas-UNICAMP, Campinas, Brazil
| | | | - Renan V Viesser
- Institute of Chemistry, University of Campinas-UNICAMP, Campinas, Brazil
| | - Uenifer R Couto
- Institute of Chemistry, University of Campinas-UNICAMP, Campinas, Brazil
| | - Cláudio F Tormena
- Institute of Chemistry, University of Campinas-UNICAMP, Campinas, Brazil
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9
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Giovanetti MD, Bitencourt LFF, Cormanich R, Sauer SPA. On the Unexpected Accuracy of the M06L Functional in the Calculation of 1JFC Spin-Spin Coupling Constants. J Chem Theory Comput 2021; 17:7712-7723. [PMID: 34751577 DOI: 10.1021/acs.jctc.1c00287] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
One-bond spin-spin coupling constants (SSCCs) between F and C are computed with density functional theory (DFT). Surprisingly, M06L stands out for its striking accuracy, outperforming any other investigated functional, including PBE0, otherwise considered one of the most reliable for couplings involving F. Although the computation of nuclear magnetic resonance (NMR) parameters involving F is known to be a challenging task, even with a rather small basis set as pcJ-1, M06L provides results with a MAD = 11.7 Hz, whereas the average deviation gets as much as 5 times larger for PBE0 (MAD = 60.0 Hz). In the context of SSCCs on the order of 300 Hz, this is particularly remarkable. We find that the accuracy of M06L/pcJ-1 in predicting 1JFC constants does not stem from a well-suited exchange or correlation part of the functional. Instead, it is believed to arise from a fortuitous cancellation of errors, as revealed by investigating the convergence of the basis set. Our findings also indicate that 1JFC constants are highly dependent on the amount of exact exchange included in the expression of the functional, with large fractions being critically important to achieving satisfactory results. Studying the effects of the geometry on 1JFC, we find that optimizing the geometry at the level of theory used to calculate SSCCs generally improves the quality of the results, although the combination of a M06-2X/aug-cc-pVTZ geometry with M06L/pcJ-1 1JFC constants best reproduces the experimental data for organofluorine compounds (with the exception of fluoroalkenes).
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Affiliation(s)
- Marinella de Giovanetti
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | | | - Rodrigo Cormanich
- Chemistry Institute, State University of Campinas, P.O. Box 6154, 13083-970 Campinas, SP, Brazil
| | - Stephan P A Sauer
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
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10
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Tribedi S, Kitaura K, Nakajima T, Sunoj RB. On the question of steric repulsion versus noncovalent attractive interactions in chiral phosphoric acid catalyzed asymmetric reactions. Phys Chem Chem Phys 2021; 23:18936-18950. [PMID: 34612433 DOI: 10.1039/d1cp02499j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The origin of enantioselectivity in asymmetric catalysis is often built around the differential steric interaction in the enantiocontrolling transition states (TSs). A closer perusal of enantiocontrolling TSs in an increasingly diverse range of reactions has revealed that the cumulative effect of weak noncovalent interactions could even outweigh the steric effects. While enunciating this balance is conspicuously important, quantification of such intramolecular forces within a TS continues to remain scarce and challenging. Herein, we demonstrate the utility of the fragment molecular orbital method in establishing the relative contributions of various attractive and repulsive contributions in the total interaction energy between the suitably chosen fragments in enantiocontrolling TSs. Three types of reactions of high contemporary importance, namely, axially chiral phosphoric acid (CPA) catalyzed kinetic resolution of rac-α-methyl-γ-hydroxy ester (reaction I), asymmetric dearomative amination of β-naphthols by dimethyl azodicarboxylate (IIa and IIb), and intramolecular desymmetrization of β,β-disubstituted methyl oxetanes (IIIa) and hydroxyl oxetane (IIIb), bearing a tethered alcohol (-OCH2CH2OH or -(CH2)2CH2OH), are considered. In all the five reactions, the differences in the stabilizing contributions arising due to electrostatic, charge-transfer, and dispersion interactions between the catalyst and the reacting partners in the enantiocontrolling transition states are weighed against the destabilizing exchange interaction. The balancing interactions are found to be between dispersion and exchange repulsion in reaction I, a combination of charge transfer and dispersion energies offsets the repulsive energy in reaction IIb involving the electron rich anthryl groups in the catalyst, whereas the -(CF3)2C6H4 3,3'-substituent in the catalyst (reaction IIa) leads to a trade-off between dispersion and exchange energies. In reactions IIIa and IIIb, however, electrostatic and dispersion energies help compensate the repulsive interactions. These quantitative insights on the intramolecular interactions in the stereocontrolling TSs could help in the rational design of asymmetric catalysis.
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Affiliation(s)
- Soumi Tribedi
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
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11
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Port VC, Zeoly LA, Coelho F, Cormanich RA. Through space JFH spin-spin coupling constant transmission pathways in 2-(trifluoromethyl)thiophenol: formation of unusual stabilizing bifurcated CFHS and CFSH interactions. Phys Chem Chem Phys 2021; 23:9080-9088. [PMID: 33646206 DOI: 10.1039/d0cp05887d] [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
Given its importance and the possibility of organic F to participate in hydrogen bonds (H-bonds), the understanding of its behavior as a H-bond acceptor with different donors is crucial. The interest in organofluorine compounds and the works related to the study of the participation of this atom in non-covalent interactions is constantly growing. Following recent studies in this subject, we evaluated the existence of two bifurcated intramolecular interactions, a bifurcated CFHS H-bond in the cis conformer of 2-trifluoromethylthiophenol and an unusual, bifurcated CFSH interaction in the trans conformer. The JFH spin-spin coupling constant (SSCC) was evaluated for 2-trifluoromethylthiophenol both experimentally by 1H and 19F NMR and theoretically using the natural bond orbitals (NBO), the quantum theory of atoms in molecules (QTAIM) and the non-covalent interactions (NCI) framework. Although both interactions are crucial for the stabilization of the conformer geometries, the observed positive JFH spin-spin coupling constant (SSCC) is mainly resultant from the trans conformer, which has a large calculated positive SSCC, and is transmitted through steric interactions involving the F lone pairs and the σSH bonding orbital.
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Affiliation(s)
- Vinícius C Port
- University of Campinas, Chemistry Institute, Monteiro Lobato Street, Campinas, São Paulo 13083-862, Brazil.
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12
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13
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Elguero J, Alkorta I, Del Bene JE. Calculated coupling constants 1 J(X-Y) and 1 K(X-Y), and fundamental relationships among the reduced coupling constants for molecules H m X-YH n , with X, Y ═ 1 H, 7 Li, 9 Be, 11 B, 13 C, 15 N, 17 O, 19 F, 31 P, 33 S, and 35 Cl. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2020; 58:727-732. [PMID: 32247293 DOI: 10.1002/mrc.5026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/24/2020] [Accepted: 03/26/2020] [Indexed: 06/11/2023]
Abstract
Equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) calculations have been performed to determine coupling constants 1 J(X-Y) for 65 molecules Hm X-YHn , with X,Y ═ 1 H, 7 Li, 9 Be, 11 B, 13 C, 15 N, 17 O, 19 F, 31 P, 33 S, and 35 Cl. The computed 1 J(X-Y) values are in good agreement with available experimental data. The reduced coupling constants 1 K(X-Y) have been derived from 1 J(X-Y) by removing the dependence on the magnetogyric ratios of X and Y. Patterns are found for the reduced coupling constants on a 1 K(X-Y) surface that are related to the positions of X and Y in the periodic table.
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Affiliation(s)
- José Elguero
- Instituto de Química Médica (CSIC), Madrid, Spain
| | - Ibon Alkorta
- Instituto de Química Médica (CSIC), Madrid, Spain
| | - Janet E Del Bene
- Department of Chemistry, Youngstown State University, Youngstown, Ohio, USA
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14
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Howe PWA. Recent developments in the use of fluorine NMR in synthesis and characterisation. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2020; 118-119:1-9. [PMID: 32883447 DOI: 10.1016/j.pnmrs.2020.02.002] [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: 01/08/2020] [Revised: 02/14/2020] [Accepted: 02/20/2020] [Indexed: 06/11/2023]
Abstract
A review of developments in fluorine NMR of relevance to synthesis, characterisation and industrial applications of small organic molecules. Developments considered include those in spectrometer technology, computational methods and pulse sequences. The review of 80 references outlines applications in areas of identification, quantitation, mixture analysis, reaction monitoring, environmental studies and fragment-based drug design.
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Affiliation(s)
- Peter W A Howe
- Syngenta, Jealott's Hill Research Centre, Bracknell, Berkshire RG42 6EY, UK.
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15
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Saielli G. One-bond 1 J( 15 N─ 19 F) spin-spin coupling constants of cationic fluorinating reagents: Insights from DFT calculations. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2020; 58:548-558. [PMID: 31814167 DOI: 10.1002/mrc.4962] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 10/21/2019] [Accepted: 10/25/2019] [Indexed: 06/10/2023]
Abstract
We have investigated, by means of density functional theory protocols, the one-bond 1 J(15 N─19 F) spin-spin coupling constants in a series of fluorinating reagents, containing the N─F bond, recently studied experimentally. The results of the calculations show a very good linear relationship with the experimental values, even though only the M06-2X(PCM)/pcJ-2//B3LYP/6-311G(d,p) level affords a very low mean absolute error. The calculations allow to analyze the various molecular orbitals contributions to the J coupling and to rationalize the observed positive sign, corresponding to a negative sign of the reduced spin-pin coupling constant K(N─F). Moreover, of the four Ramsey contributions, only the diamagnetic spin orbit is negligible, whereas the paramagnetic spin orbit and spin dipole terms decrease the magnitude of the Fermi contact (FC) term by an amount that goes from a minimum of 35% up to more than 60% of the FC term itself. Several effects have been investigated, namely, the contribution of the long-range solvent reaction field, relativistic corrections, and conformational and vibrational effects.
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Affiliation(s)
- Giacomo Saielli
- CNR Institute on Membrane Technology, Unit of Padova, Padova, Italy
- Department of Chemical Sciences, University of Padova, Padova, Italy
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16
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Zeoly LA, Coelho F, Cormanich RA. Intramolecular H-Bond Is Formed in 2-Fluorophenol and 2-Fluorothiophenol, but It May Not Be the Main Pathway of the JFH Coupling Constant Transmission. J Phys Chem A 2019; 123:10072-10078. [PMID: 31661281 DOI: 10.1021/acs.jpca.9b07970] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The intramolecular CF···HX (X = O or S) H-bond and JFH spin-spin coupling constants (SSCCs) in 2-fluorophenol and 2-fluorothiophenol were investigated experimentally by 1H and 19F NMR and theoretically in the framework of the natural bond orbital analysis. In contrast with recent findings from the literature, the results obtained in this work showed that an intramolecular H-bond is formed in the cis conformers and that it has an electrostatic origin. Such an intramolecular electrostatic H-bond is the interaction that rules the conformational preferences on these compounds. Moreover, the natural J-coupling analysis indicated that the JHF SSCC in 2-fluorophenol has its origin on LP(F)/σOH steric interactions and should be labeled as 4TSJHF. On the other hand, the analogue SSCC for 2-fluorothiophenol has its origin on the intramolecular H-bond LP(F) → σSH* hyperconjugative interaction and should be described as a 1hJFH SSCC.
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Affiliation(s)
- Lucas A Zeoly
- Department of Organic Chemistry , Institute of Chemistry , Campinas , São Paulo 13083-970 , Brazil
| | - Fernando Coelho
- Department of Organic Chemistry , Institute of Chemistry , Campinas , São Paulo 13083-970 , Brazil
| | - Rodrigo A Cormanich
- Department of Organic Chemistry , Institute of Chemistry , Campinas , São Paulo 13083-970 , Brazil
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