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Ovalioglu H. Sample age effect on parameters of dynamic nuclear polarization in certain difluorobenzen isomers/MC800 asphaltene suspensions. OPEN CHEM 2022. [DOI: 10.1515/chem-2021-0114] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Because of magnetic spin–spin interactivity between 19F nucleus of the solvent and delocalized electrons on the MC800 asphaltene, the Overhauser dynamic nuclear polarization (DNP) method is able to give a substantial boost in the signal acquired from studies focused on nuclear magnetic resonance (NMR). The suspensions of asphaltene in difluorobenzene isomers were studied using Overhauser effect type DNP and NMR investigations at room temperature in a small magnetic field of 1.53 mT. The used asphaltene was obtained from MC800 liquid asphalt from Heavy Iran. Each sample of the solvent medium was produced at three different concentrations of asphaltene. These samples were stored in the refrigerator for 7 years, until DNP parameters were found by new DNP tests. As a result, the influence of sample age on parameters of DNP was studied, and then the findings were analyzed.
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Affiliation(s)
- Hüseyin Ovalioglu
- Physics Department, Faculty of Arts and Sciences, Bursa Uludag University , 16059 , Bursa , Turkey
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2
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3
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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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4
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Koch A, Stamboliyska B, Mikhova B, Breznica-Selmani P, Mladenovska K, Popovski E. Calculations of 13 C NMR chemical shifts and F-C coupling constants of ciprofloxacin. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2019; 57:S75-S84. [PMID: 30605227 DOI: 10.1002/mrc.4827] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 12/19/2018] [Accepted: 12/20/2018] [Indexed: 06/09/2023]
Abstract
Ciprofloxacin is a widely used fluoroquinolone antibiotic. In this work, a comprehensive evaluation of MP2 and DFT with different functionals and basis sets was carried out to select the most suitable level of theory for the study of the NMR properties of ciprofloxacin. Their relative predictive capabilities were evaluated comparing the theoretically predicted and experimental spectral data. Our computational results indicated that in contrast to the solid state, the molecule of ciprofloxacin does not exist as a zwitterion in gaseous state. The results of the calculations of the chemical shifts most close to the experimental were obtained with B3LYP/aug-cc-pVDZ. The F-C coupling constants were calculated systematically with different DFT methods and several basis sets. In general, the calculations of the coupling constants with the BHandH computational method including the applied in this work 6-311++G**, EPRII, and EPRIII basis sets showed a good reproducibility of the experimental values of the coupling constants.
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Affiliation(s)
- Andreas Koch
- Department of Chemistry, University of Potsdam, Potsdam, Germany
| | - Bistra Stamboliyska
- Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Bozhana Mikhova
- Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | | | - Kristina Mladenovska
- Faculty of Pharmacy, University "Ss Cyril and Methodius", Skopje, Republic of Macedonia
| | - Emil Popovski
- Institute of Chemistry, Faculty of Natural Sciences and Mathematics, University "Ss. Cyril and Methodius", Skopje, Republic of Macedonia
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5
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Sharma H, Bhattacharyya PK. Association of phenyldiboronic acids with hydrogen bond acceptors to form hydrogen bonded DD·AA-type complexes: a DFT study. NEW J CHEM 2017. [DOI: 10.1039/c7nj01739a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
DD·AA-type complexes of phenyldiboronic acids.
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6
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Gryff-Keller A, Szczeciński P. An efficient DFT method of predicting the one-, two- and three-bond indirect spin–spin coupling constants involving a fluorine nucleus in fluoroalkanes. RSC Adv 2016. [DOI: 10.1039/c6ra15343g] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The values of the indirect nuclear spin–spin coupling constants for a series of aliphatic fluorocompounds have been calculated using DFT-based methods and compared with the experimental values of these parameters.
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Affiliation(s)
- Adam Gryff-Keller
- Faculty of Chemistry
- Warsaw University of Technology
- 00-664 Warszawa
- Poland
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7
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DFT study of molecular structures and 13C NMR parameters of two fluorinated biphenyls and their η6-tricarbonylchromium complexes. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2015.02.081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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8
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Contreras RH, Llorente T, Ducati LC, Tormena CF. Revisiting NMR Through-Space JFF Spin–Spin Coupling Constants for Getting Insight into Proximate F---F Interactions. J Phys Chem A 2014; 118:5068-75. [DOI: 10.1021/jp501929t] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Rubén H. Contreras
- Department
of Physics, FCEyN, University of Buenos Aires and IFIBA-CONICET, C1053ABJ Buenos Aires, Argentina
| | - Tomás Llorente
- Department
of Physics, FCEyN, University of Buenos Aires and IFIBA-CONICET, C1053ABJ Buenos Aires, Argentina
| | - Lucas Colucci Ducati
- Institute
of Chemistry, University of Sao Paulo − USP, P.O. Box 26077, 05513-970 Sao Paulo - SP, Brazil
| | - Cláudio Francisco Tormena
- Chemistry
Institute, University of Campinas - UNICAMP, P.O. Box 6154, 13083-970 Campinas - SP, Brazil
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9
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Kirimli HE, Ovalioglu H. 19F Dynamic Nuclear Polarization and SEM in Suspensions Consisting of Fluorobenzene Derivatives and Asphaltene Extracted from MC-800 Liquid Asphalt. J DISPER SCI TECHNOL 2014. [DOI: 10.1080/01932691.2013.767208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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10
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Gryff-Keller A, Szczeciński P. A successful DFT calculation of carbon-13 NMR chemical shifts and carbon–fluorine spin–spin coupling constants in (η6-fluoroarene)tricarbonylchromium complexes. RSC Adv 2014. [DOI: 10.1039/c4ra01249f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Carbon-13 isotropic shielding constants and C–F spin–spin coupling constants for fluorobenzene, 3- and 4-dimethylaminofluorobenzene as well as for their tricarbonylchromium complexes have been calculated using DFT methods.
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Affiliation(s)
- Adam Gryff-Keller
- Department of Chemistry
- Warsaw University of Technology
- 00-664 Warszawa, Poland
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11
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San Fabián J, García de la Vega JM, Suardíaz R, Fernández-Oliva M, Pérez C, Crespo-Otero R, Contreras RH. Computational NMR coupling constants: shifting and scaling factors for evaluating 1JCH. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2013; 51:775-787. [PMID: 24123317 DOI: 10.1002/mrc.4014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/28/2013] [Accepted: 09/02/2013] [Indexed: 06/02/2023]
Abstract
Optimized shifting and/or scaling factors for calculating one-bond carbon-hydrogen spin-spin coupling constants have been determined for 35 combinations of representative functionals (PBE, B3LYP, B3P86, B97-2 and M06-L) and basis sets (TZVP, HIII-su3, EPR-III, aug-cc-pVTZ-J, ccJ-pVDZ, ccJ-pVTZ, ccJ-pVQZ, pcJ-2 and pcJ-3) using 68 organic molecular systems with 88 (1)JCH couplings including different types of hybridized carbon atoms. Density functional theory assessment for the determination of (1)JCH coupling constants is examined, comparing the computed and experimental values. The use of shifting constants for obtaining the calculated coupling improves substantially the results, and most models become qualitatively similar. Thus, for the whole set of couplings and for all approaches excluding those using the M06 functional, the root-mean-square deviations lie between 4.7 and 16.4 Hz and are reduced to 4-6.5 Hz when shifting constants are considered. Alternatively, when a specific rovibrational contribution of 5 Hz is subtracted from the experimental values, good results are obtained with PBE, B3P86 and B97-2 functionals in combination with HIII-su3, aug-cc-pVTZ-J and pcJ-2 basis sets.
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Affiliation(s)
- J San Fabián
- Departamento de Química Física Aplicada, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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12
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da Silva AM, Ghosh A, Chaudhuri P. Effect of Hydrogen Bond Formation on the NMR Properties of Glycine–HCN Complexes. J Phys Chem A 2013; 117:10274-85. [DOI: 10.1021/jp4056818] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Arnaldo Machado da Silva
- Departamento
de Física, Universidade Federal do Amazonas, 69077-000 Manaus, AM, Brazil
- Departamento
de Física, Universidade Federal de São Carlos, São Paulo 13565-905, Brazil
| | - Angsula Ghosh
- Departamento
de Física, Universidade Federal do Amazonas, 69077-000 Manaus, AM, Brazil
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Favaro DC, Contreras RH, Tormena CF. Unusual Through-Space, TS, Pathway for the Transmission of JFHf Coupling: 2-Fluorobenzaldehyde Study Case. J Phys Chem A 2013; 117:7939-45. [DOI: 10.1021/jp402618c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Denize C. Favaro
- Chemistry Institute, University of Campinas - UNICAMP, P.O. Box: 6154, 13084-862
Campinas, Sao Paulo, Brazil
| | - Rubén H. Contreras
- Department of Physics, FCEyN, University of Buenos Aires and IFIBA-CONICET, Buenos
Aires, Argentina
| | - Cláudio F. Tormena
- Chemistry Institute, University of Campinas - UNICAMP, P.O. Box: 6154, 13084-862
Campinas, Sao Paulo, Brazil
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14
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Favaro DC, Contreras RH, Tormena CF. The electronic origin of unusually large (n)J(FN) coupling constants in some fluoroximes. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2013; 51:334-338. [PMID: 23554215 DOI: 10.1002/mrc.3950] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 02/21/2013] [Accepted: 03/04/2013] [Indexed: 06/02/2023]
Abstract
SOPPA(CCSD) calculations show that the FC term is the most important contribution to the through-space transmission of JFN coupling constants for the fluoroximes studied in this work. Because of the well-known behavior of FC term, a new rationalization for the experimental (TS)JFN SSCC is presented. It is mainly based on the overlap matrix (Sij) between fluorine and nitrogen lone pairs obtained from NBO analyses. An expression is proposed to take into account the influence of the electronic density (Dij) between coupled nuclei as well as the s% character at the site of the coupling nuclei of bonds and non-bonding electron pairs involved in Dij. In using this approach, a linear correlation between (TS)JFN versus Dij is obtained. The most important aspect of this rationalization is related to the facility for understanding the behavior of some unusual experimental coupling constants. It is shown that, at least in this case, the electronic origin of the so-called through-space coupling is transmitted through to the overlap of orbitals on the coupled atoms, suggesting that, at least for these compounds, instead of through-space coupling, it should better be dubbed as 'through overlapping orbital coupling'.
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Affiliation(s)
- Denize C Favaro
- Chemistry Institute, State University of Campinas, Campinas, Sao Paulo, Brazil
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15
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Contreras RH, Tormena CF, Ducati LC. Transmission Mechanisms of the Fermi-Contact Term of Spin–Spin Couplings. SCIENCE AND TECHNOLOGY OF ATOMIC, MOLECULAR, CONDENSED MATTER & BIOLOGICAL SYSTEMS 2013. [DOI: 10.1016/b978-0-444-59411-2.00008-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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16
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Contreras RH, Ferraro M, Ruiz de Azúa MC, Aucar GA. Brief Account of Nonrelativistic Theory of NMR Parameters. SCIENCE AND TECHNOLOGY OF ATOMIC, MOLECULAR, CONDENSED MATTER & BIOLOGICAL SYSTEMS 2013. [DOI: 10.1016/b978-0-444-59411-2.00002-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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17
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de Rezende FMP, Moreira MA, Cormanich RA, Freitas MP. Conformational analysis, stereoelectronic interactions and NMR properties of 2-fluorobicyclo[2.2.1]heptan-7-ols. Beilstein J Org Chem 2012; 8:1227-32. [PMID: 23019452 PMCID: PMC3458742 DOI: 10.3762/bjoc.8.137] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Accepted: 07/11/2012] [Indexed: 12/05/2022] Open
Abstract
Four diastereoisomers of 2-fluorobicyclo[2.2.1]heptan-7-ols were computationally investigated by using quantum-chemical calculations, and their relative energies were analyzed on the basis of stereoelectronic interactions, particularly the presence or otherwise of the F∙∙∙HO intramolecular hydrogen bond in the syn-exo isomer. It was found through NBO and AIM analyses that such an interaction contributes to structural stabilization and that the 1hJF,H(O) coupling constant in the syn-exo isomer is modulated by the nF→σ*OH interaction, i.e., the quantum nature of the F∙∙∙HO hydrogen bond.
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Affiliation(s)
- Fátima M P de Rezende
- Department of Chemistry, Federal University of Lavras, P.O. Box 3037, 37200-000, Lavras, MG, Brazil
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18
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Freitas MP, Bühl M. Density functional study of the one-bond C F coupling constant in α-fluorocarbonyl and α-fluorosulfonyl compounds. J Fluor Chem 2012. [DOI: 10.1016/j.jfluchem.2012.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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19
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Fonseca TAO, Ramalho TC, Freitas MP. F···HO intramolecular hydrogen bond as the main transmission mechanism for (1h)J(F,H(O)) coupling constant in 2'-fluoroflavonol. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2012; 50:551-556. [PMID: 22736400 DOI: 10.1002/mrc.3837] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 05/24/2012] [Accepted: 05/25/2012] [Indexed: 06/01/2023]
Abstract
Flavonoids are useful compounds in medicinal chemistry and exhibit conformational isomerism, which is ruled by intramolecular interactions. One of the main intramolecular forces governing the stability of conformations is the hydrogen bond. Hydrogen bond involving fluorine covalently bonded to carbon has been found to be rare, but it appears in 2'-fluoroflavonol, although the F···HO hydrogen bond cannot be considered the main effect governing the conformational stability of this compound. Because (19)F is magnetically active and suitable for NMR studies, the (1h)J(F,H(O)) coupling constant can be used as a probe for such an interaction in 2'-fluoroflavonol. In fact, the (1h)J(F,H(O)) coupling was computationally analyzed in this work, and the F···HO hydrogen bond was found to be its main transmission mechanism, which modulates this coupling in 2'-fluoroflavonol, rather than overlap of proximate electronic clouds, such as in 2-fluorophenol.
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Affiliation(s)
- Tânia A O Fonseca
- Department of Chemistry, Federal University of Lavras, Lavras, Minas Gerais, Brazil
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20
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Queiroz LHK, Giraudeau P, dos Santos FAB, de Oliveira KT, Ferreira AG. Real-time mechanistic monitoring of an acetal hydrolysis using ultrafast 2D NMR. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2012; 50:496-501. [PMID: 22615138 DOI: 10.1002/mrc.3827] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 04/04/2012] [Accepted: 04/22/2012] [Indexed: 06/01/2023]
Abstract
Ultrafast (UF) 2D NMR makes it possible to obtain a 2D NMR spectrum in less than a second. Here, UF-HSQC experiments are used for the real-time mechanistic study of an acetal hydrolysis at ¹³C natural abundance, and it is possible to characterize the presence of the hemiacetal, an intermediate with a well-known short lifetime. The assignments are confirmed and rationalized by quantum calculations of ¹H and ¹³C NMR chemical shifts and natural bonding orbital analysis.
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Affiliation(s)
- Luiz H K Queiroz
- Laboratório de Ressonância Magnética Nuclear, Departamento de Química, Universidade Federal de São Carlos (UFSCar), São Carlos, SP, Brazil.
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21
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Ducati LC, Contreras RH, Tormena CF. Unexpected geometrical effects on paramagnetic spin-orbit and spin-dipolar 2J(FF) couplings. J Phys Chem A 2012; 116:4930-3. [PMID: 22533483 DOI: 10.1021/jp301912x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The second-rank tensor character of the paramagnetic spin-orbit and spin-dipolar contributions to nuclear spin-spin coupling constants is usually ignored when NMR measurements are carried out in the isotropic phase. However, in this study it is shown that isotropic (2)J(FF) couplings strongly depend on the relative orientation of the C-F bonds containing the coupling nuclei and the eigenvectors of such tensors. Predictions about such effect are obtained using a qualitative approach based on the polarization propagator formalism at the RPA, and results are corroborated performing high-level ab initio spin-spin coupling calculations at the SOPPA(CCSD)/EPR-III//MP2/EPR-III level in a model system. It is highlighted that no calculations at the RPA level were carried out in this work. The quite promising results reported in this paper suggest that similar properties are expected to hold for the second-rank nuclear magnetic shielding tensor.
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Affiliation(s)
- Lucas C Ducati
- Chemistry Institute, State University of Campinas, Caixa Postal 6154, 13084-971 Campinas, SP, Brazil
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22
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23
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Favaro DC, Ducati LC, dos Santos FP, Contreras RH, Tormena CF. Stereochemical dependence of 3JCH coupling constants in 2-substituted 4-t-butyl-cyclohexanone and their alcohol derivatives. J Phys Chem A 2011; 115:14539-45. [PMID: 22060817 DOI: 10.1021/jp2083456] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Theoretical and experimental studies on (3)J(C2H6eq) NMR spin-spin coupling constants in both the 2-X-4-t-butyl-cyclohexanone (X = H, CH(3), F, Cl, and Br) and in their alcohol derivatives series are reported. Results thus found are rationalized in terms of the transmission of the Fermi contact contribution to such couplings. To this end, dependencies of (3)J(C2H6eq) couplings versus the C(2)-C(1)-C(6) angle are compared in both series for equatorial and axial X orientations. The main trend is described in terms of the rear lobes interaction. Besides, for X = halogen atom in equatorial orientation a rather strong interaction between oxygen and halogen lone pairs is observed, and its influence on (3)J(C2H6eq) couplings is discussed and rationalized in terms of different Fermi contact transmission pathways.
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Affiliation(s)
- Denize C Favaro
- Chemistry Institute, State University of Campinas, Campinas SP, Brazil
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24
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Cormanich RA, Moreira MA, Freitas MP, Ramalho TC, Anconi CPA, Rittner R, Contreras RH, Tormena CF. 1hJFH coupling in 2-fluorophenol revisited: is intramolecular hydrogen bond responsible for this long-range coupling? MAGNETIC RESONANCE IN CHEMISTRY : MRC 2011; 49:763-767. [PMID: 22095853 DOI: 10.1002/mrc.2838] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 08/29/2011] [Accepted: 08/31/2011] [Indexed: 05/31/2023]
Abstract
The present study shows that a hydrogen bond between the OH group and the fluorine atom is not involved in the (1h)J(FH) spin-spin coupling transmission either for 4-bromo-2-fluorophenol or 2-fluorophenol. In fact, according to a quantum theory of atoms in molecules analysis, no bond critical point is found between O-H and F moieties. The nature of the transmission mechanism of the Fermi contact term of the (1h)J(FH) spin-spin coupling is studied by analyzing canonical molecular orbitals (see J. Phys. Chem. A 2010, 114, 1044), and it is observed that virtual orbitals play only a quite minor role in its transmission. This is typical of a Fermi contact term transmitted mainly through exchange interactions owing to the overlap of proximate electronic clouds; therefore, it is suggested to identify them as (nTS)J(FH) coupling where n stands for the number of formal bonds separating the coupling nuclei. In the cases studied in this work is n = 4. Results presented in this work could provide an interesting rationalization for different experimental signs known in the current literature for proximate J(FH) couplings.
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25
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Anizelli PR, Favaro DC, Contreras RH, Tormena CF. Effect of Electronic Interactions on NMR 1JCF and 2JCF Couplings in cis- and trans-4-t-Butyl-2-fluorocyclohexanones and Their Alcohol Derivatives. J Phys Chem A 2011; 115:5684-92. [DOI: 10.1021/jp202592c] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Pedro R. Anizelli
- Chemistry Institute, University of Campinas, Post Office Box 6154, 13084-971 Campinas, SP, Brazil
| | - Denize C. Favaro
- Chemistry Institute, University of Campinas, Post Office Box 6154, 13084-971 Campinas, SP, Brazil
| | - Rubén H. Contreras
- Department of Physics, FCEyN, University of Buenos Aires and IFIBA-CONICET, Buenos Aires, Argentina
| | - Cláudio F. Tormena
- Chemistry Institute, University of Campinas, Post Office Box 6154, 13084-971 Campinas, SP, Brazil
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