Analysis of Canonical Molecular Orbitals to Identify Fermi Contact Coupling Pathways. 1. Through-Space Transmission by Overlap of <sup>31</sup>P Lone Pairs

Contreras, Rubén H.; Gotelli, Gustavo A.; Ducati, Lucas C.; Barbosa, Thaís M.; Tormena, Cláudio F.

doi:10.1021/jp908970f

Cited by 24 publications

(31 citation statements)

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“…The FC term of NMR spin-spin coupling constants is also computed based on the known form of propagation of the Fermi hole through a canonical molecular orbital (CMO). [100] It is also reported that n J XH computed for unsaturated nitriles using B3LYP/ILGO-11//B3LYP is in perfect agreement with the measured values. [101] …”

Section: Computation Of Long-range J-couplingssupporting

confidence: 63%

Measurement and Applications of Long‐Range Heteronuclear Scalar Couplings: Recent Experimental and Theoretical Developments

2012

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The use of long-range heteronuclear couplings, in association with (1)H-(1)H scalar couplings and NOE restraints, has acquired growing importance for the determination of the relative stereochemistry, and structural and conformational information of organic and biological molecules. However, the routine use of such couplings is hindered by the inherent difficulties in their measurement. Prior to the advancement in experimental techniques, both long-range homo- and heteronuclear scalar couplings were not easily accessible, especially for very large molecules. The development of a large number of multidimensional NMR experimental methodologies has alleviated the complications associated with the measurement of couplings of smaller strengths. Subsequent application of these methods and the utilization of determined J-couplings for structure calculations have revolutionized this area of research. Problems in organic, inorganic and biophysical chemistry have also been solved by utilizing the short- and long-range heteronuclear couplings. In this minireview, we discuss the advantages and limitations of a number of experimental techniques reported in recent times for the measurement of long-range heteronuclear couplings and a few selected applications of such couplings. This includes the study of medium- to larger-sized molecules in a variety of applications, especially in the study of hydrogen bonding in biological systems. The utilization of these couplings in conjunction with theoretical calculations to arrive at conclusions on the hyperconjugation, configurational analysis and the effect of the electronegativity of the substituents is also discussed.

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Section: Computation Of Long-range J-couplingssupporting

confidence: 63%

Measurement and Applications of Long‐Range Heteronuclear Scalar Couplings: Recent Experimental and Theoretical Developments

2012

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“…Recently, a new approach to study coupling pathways for the FC term of SSCCs, was presented and it was dubbed FCCP-CMO [24,25] , which stands for FC coupling pathways studied using canonical molecular orbitals. The corresponding analysis is based on the polarization propagator (PP) expression for the FC term, Eqns (1-3) [26][27][28][29] Figure 1.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, a new approach to study coupling pathways for the FC term of SSCCs, was presented and it was dubbed FCCP‐CMO , which stands for FC coupling pathways studied using canonical molecular orbitals. The corresponding analysis is based on the polarization propagator (PP) expression for the FC term, Eqns (1–3)

{}^{4}J_{FH}^{FC} = Ω^{FC} \sum_{i a, j b} {}^{4}J_{i a, j b}^{FC} (FH)

where each term in this sum can be expressed as

{}^{4}J {_{i a, j b}^{FC}}_{} (F H) = {}^{3}W_{i a, j b} [U_{i a, H}^{FC} U_{j b, F}^{FC} + U_{i a, F}^{FC} U_{j b, H}^{FC}]

and

{}^{3}W_{i a, j b} = {((), {}^{3}A + {}^{3}B)}_{i a, j b}^{- 1}

are the elements of the inverse of the triplet PP matrix, and matrices 3 A and 3 B can be written in terms of bielectronic molecular integrals.…”

Section: Resultsmentioning

confidence: 99%

^1hJ_FHcoupling in 2‐fluorophenol revisited: Is intramolecular hydrogen bond responsible for this long‐range coupling?

Cormanich

Moreira

Freitas

et al. 2011

Magnetic Reson in Chemistry

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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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“…This is the case of the Lazzeretti et al 's22 approach and of the coupling energy density (CED) approach developed by Malkina and Malkin 23. Recently, a different and very simple approach was presented, which can be used by any NMR laboratory with access to the following common Quantum Chemistry software; the Gaussian 03 package16 of programs and the NBO 5.0 program developed by Weinhold et al 14 This approach24 was dubbed FCCP–CMOs (the study of FC coupling pathways by analyzing CMOs). This analysis is applied in this work to study how the FC term of 2 J C 2 H 3 and 2 J C 3 H 2 SSCCs is transmitted in series 1 and 2 .…”

Section: Fc Term For Ssccmentioning

confidence: 99%

“…A description of the FCCP–CMO analysis and how to properly carry out the analysis of results from calculations can be found in Ref. 24.…”

Section: Fc Term For Ssccmentioning

confidence: 99%

Difference between 2JC2H3 and 2JC3H2 spin-spin couplings in heterocyclic five- and six-membered rings as a probe for studying σ-ring currents: a quantum chemical analysis

et al. 2010

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Adequate analyses of canonical molecular orbitals (CMOs) can provide rather detailed information on the importance of different σ-Fermi contact (FC) coupling pathways (FC term transmitted through the σ-skeleton). Knowledge of the spatial distribution of CMOs is obtained by expanding them in terms of natural bond orbitals (NBOs). Their relative importance for transmitting the σ-FC contribution to a given spin-spin coupling constants (SSCCs) is estimated by resorting to the expression of the FC term given by the polarisation propagator formalism. In this way, it is possible to classify the effects affecting such couplings in two different ways: delocalisation interactions taking place in the neighbourhood of the coupling nuclei and 'round the ring' effects. The latter, associated with σ-ring currents, are observed to yield significant differences between the FC terms of (2)J(C2H3) and (2)J(C3H2) SSCCs which, consequently, are taken as probes to gauge the differences in σ-ring currents for the five-membered rings (furan, thiophene, selenophene and pyrrol) and also for the six-membered rings (benzene, pyridine, protonated pyridine and N-oxide pyridine) used in the present study.

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Analysis of Canonical Molecular Orbitals to Identify Fermi Contact Coupling Pathways. 1. Through-Space Transmission by Overlap of ³¹P Lone Pairs

Cited by 24 publications

References 50 publications

Measurement and Applications of Long‐Range Heteronuclear Scalar Couplings: Recent Experimental and Theoretical Developments

Measurement and Applications of Long‐Range Heteronuclear Scalar Couplings: Recent Experimental and Theoretical Developments

^1hJ_FHcoupling in 2‐fluorophenol revisited: Is intramolecular hydrogen bond responsible for this long‐range coupling?

Difference between 2JC2H3 and 2JC3H2 spin-spin couplings in heterocyclic five- and six-membered rings as a probe for studying σ-ring currents: a quantum chemical analysis

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Analysis of Canonical Molecular Orbitals to Identify Fermi Contact Coupling Pathways. 1. Through-Space Transmission by Overlap of 31P Lone Pairs

Cited by 24 publications

References 50 publications

Measurement and Applications of Long‐Range Heteronuclear Scalar Couplings: Recent Experimental and Theoretical Developments

Measurement and Applications of Long‐Range Heteronuclear Scalar Couplings: Recent Experimental and Theoretical Developments

1hJFHcoupling in 2‐fluorophenol revisited: Is intramolecular hydrogen bond responsible for this long‐range coupling?

Difference between 2JC2H3 and 2JC3H2 spin-spin couplings in heterocyclic five- and six-membered rings as a probe for studying σ-ring currents: a quantum chemical analysis

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Analysis of Canonical Molecular Orbitals to Identify Fermi Contact Coupling Pathways. 1. Through-Space Transmission by Overlap of ³¹P Lone Pairs

^1hJ_FHcoupling in 2‐fluorophenol revisited: Is intramolecular hydrogen bond responsible for this long‐range coupling?