Determination of the <i>r</i><sub>α</sub> structures of ethylene and 1,1‐difluoroethylene by NMR of partially oriented molecules allowing for correlated deformation

Wasser, R.; Diehl, P.

doi:10.1002/mrc.1260250906

Cited by 9 publications

(6 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Δ J CC in ethene was obtained by the MASTER analysis correspondingly to the method previously applied to benzene 22 except that the CH bond length and the HCH angle were adjustable parameters in this case. Also the asymmetry parameter η CH of the interaction tensor A CH (these quantities are intrinsic to the deformational analysis 5 ) was fixed to zero …”

Section: Resultsmentioning

confidence: 99%

“…Also the asymmetry parameter η CH of the interaction tensor A CH (these quantities are intrinsic to the deformational analysis 5 ) was fixed to zero. 26 Once the various contributions are known, the anisotropic contribution is obtained from…”

Section: Resultsmentioning

confidence: 99%

“…On the contrary, both ethene and ethyne have been subjects of interest. The studies of ethene deal with the structure and the effect of the vibration−rotation interaction on the structure. , Also a rough estimate for the CC coupling anisotropy, 90 Hz, was reported . The main emphasis in ethyne focused on the odd solvent and temperature effects on the structure and order tensor. , The extreme solvent and temperature sensitivity of the structure was in ref explained on the basis of specific interactions between ethyne and LC molecules (Merck Phase 4).…”

Section: Introductionmentioning

confidence: 99%

“…The studies of ethene deal with the structure and the effect of the vibration-rotation interaction on the structure. 25,26 Also a rough estimate for the CC coupling anisotropy, 90 Hz, was reported. 25 The main emphasis in ethyne focused on the odd solvent and temperature effects on the structure and order tensor.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Experimental and Theoretical ab Initio Study of the ¹³C−¹³C Spin−Spin Coupling and ¹H and ¹³C Shielding Tensors in Ethane, Ethene, and Ethyne

et al. 1998

View full text Add to dashboard Cite

Experimentally and theoretically (ab initio) determined CC spin−spin coupling tensors and 1H and 13C nuclear shielding tensors are reported for ethane (13C2H6), ethene (13C2H4), and ethyne (13C2H2). The experimental anisotropies of the CC coupling tensors, ΔJ CC, for all these molecules, and also the combination J CC, xx − J CC, yy for ethene, were derived from sets of anisotropic couplings (D exp) analyzed from the 1H and 13C NMR spectra of molecules partially oriented in liquid−crystalline environments. Both harmonic vibrations and structural deformations arising from the correlation of vibrational and reorientational motions were taken into account in the D couplings. The ab initio calculations of all the J tensors were performed using MCSCF linear response theory. The best calculated and experimental ΔJ CC values (along with J CC, xx − J CC, yy for ethene) are found to be in good mutual agreement. Together with earlier work on the n J CC tensors in benzene, this study shows that the indirect contribution, 1/2 J CC aniso, to experimental couplings between differently hybridized carbons is small and can generally be omitted. This means that the use of experimental D CC couplings in the determination of molecular order tensors and/or conformation does not introduce serious errors. The experimental determination of the 1H and 13C shielding tensors was based on the liquid crystal director rotation by 90° in mixtures of thermotropic nematogens with opposite anisotropy of diamagnetic susceptibility. Ab initio SCF and MCSCF calculations utilizing gauge-including atomic orbitals produce results in good agreement with experiments.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Experimental and Theoretical ab Initio Study of the ¹³C−¹³C Spin−Spin Coupling and ¹H and ¹³C Shielding Tensors in Ethane, Ethene, and Ethyne

et al. 1998

View full text Add to dashboard Cite

show abstract

“…Although no spin−spin coupling constants have been measured experimentally for the molecules investigated in this study, experimental − and computed EOM-CCSD/(qzp,qz2p) values of 1 J (P−F), 1 J (B−H), and 2 J (F−F) for related systems are available and are reported in Table . It should be noted that the range of both computed and experimental values of 1 J (P−F) is large, and that the agreement between computed and experimental data is good.…”

Section: Resultsmentioning

confidence: 99%

Structures, Energies, and Spin−Spin Coupling Constants of Fluoro-Substituted 1,3-Diborata-2,4-diphosphoniocyclobutanes: Four-Member B−P−B−P Rings B₂P₂F_nH_8−n with n = 0, 1, 2, 4

2011

View full text Add to dashboard Cite

An ab initio study has been carried out to determine the structures, relative stabilities, and spin-spin coupling constants of a set of 15 fluoro-substituted 1,3-diborata-2,4-diphosphoniocyclobutanes B(2)P(2)F(n)H(8-n), for n = 0, 1, 2, 4, with four-member B-P-B-P rings. Except for B(2)P(2)F(4)H(4) with four fluorines bonded to two borons, these rings are puckered in a butterfly conformation. For a fixed number of fluorines, the isomers with B-F bonds are significantly more stable than those with P-F bonds. As the number of fluorines increases, the energy difference between the most stable isomer and the other isomers increases. Transition structures which interconvert axial and equatorial positions present relatively small inversion barriers. Coupling constants involving (31)P, namely, (1)J(B-P), (1)J(P-F), (2)J(P-P), (2)J(P-F), and (3)J(P-F) are large and are capable of providing structural information. They are sensitive to the number of fluorines present and can discriminate between axial, equatorial, and geminal B-F and P-F bonds, although not all do this to the same extent. (1)J(B-P) and (2)J(P-P) are similar in equilibrium and transition structures. Although transition structures no longer discriminate between axial and equatorial bonds, (1)J(P-F) and (3)J(P-F) remain sensitive to the number of fluorine atoms present.

show abstract

Structure ofp-tetrafluorobenzoquinone: interaction with nematic liquid crystals

Arfaoui¹,

Haloui²

2000

Magn. Reson. Chem.

View full text Add to dashboard Cite

The orientation of p‐tetrafluorobenzoquinone in four nematic liquid crystals with different aromaticities was determined by measuring the fluorine– fluorine and the fluorine– carbon scalar and dipolar couplings. Signs of the J(F,F) and the J(C,F) were determined without ambiguity. The experimental geometry was compared with those obtained by diffraction techniques and by ab initio molecular orbital calculations. Assuming a solvent– solute interaction potential based entirely on dispersion forces does not agree with experimental observations. The discrepancies are partly due to the formation of charge‐transfer molecular complexes. This latter contribution was confirmed by UV spectrophotometric measurements. Copyright © 2000 John Wiley & Sons, Ltd.

show abstract

Determination of the r_α structures of ethylene and 1,1‐difluoroethylene by NMR of partially oriented molecules allowing for correlated deformation

Cited by 9 publications

References 16 publications

Experimental and Theoretical ab Initio Study of the ¹³C−¹³C Spin−Spin Coupling and ¹H and ¹³C Shielding Tensors in Ethane, Ethene, and Ethyne

Experimental and Theoretical ab Initio Study of the ¹³C−¹³C Spin−Spin Coupling and ¹H and ¹³C Shielding Tensors in Ethane, Ethene, and Ethyne

Structures, Energies, and Spin−Spin Coupling Constants of Fluoro-Substituted 1,3-Diborata-2,4-diphosphoniocyclobutanes: Four-Member B−P−B−P Rings B₂P₂F_nH_8−n with n = 0, 1, 2, 4

Structure ofp-tetrafluorobenzoquinone: interaction with nematic liquid crystals

Contact Info

Product

Resources

About

Determination of the rα structures of ethylene and 1,1‐difluoroethylene by NMR of partially oriented molecules allowing for correlated deformation

Cited by 9 publications

References 16 publications

Experimental and Theoretical ab Initio Study of the 13C−13C Spin−Spin Coupling and 1H and 13C Shielding Tensors in Ethane, Ethene, and Ethyne

Experimental and Theoretical ab Initio Study of the 13C−13C Spin−Spin Coupling and 1H and 13C Shielding Tensors in Ethane, Ethene, and Ethyne

Structures, Energies, and Spin−Spin Coupling Constants of Fluoro-Substituted 1,3-Diborata-2,4-diphosphoniocyclobutanes: Four-Member B−P−B−P Rings B2P2FnH8−n with n = 0, 1, 2, 4

Structure ofp-tetrafluorobenzoquinone: interaction with nematic liquid crystals

Contact Info

Product

Resources

About

Determination of the r_α structures of ethylene and 1,1‐difluoroethylene by NMR of partially oriented molecules allowing for correlated deformation

Experimental and Theoretical ab Initio Study of the ¹³C−¹³C Spin−Spin Coupling and ¹H and ¹³C Shielding Tensors in Ethane, Ethene, and Ethyne

Experimental and Theoretical ab Initio Study of the ¹³C−¹³C Spin−Spin Coupling and ¹H and ¹³C Shielding Tensors in Ethane, Ethene, and Ethyne

Structures, Energies, and Spin−Spin Coupling Constants of Fluoro-Substituted 1,3-Diborata-2,4-diphosphoniocyclobutanes: Four-Member B−P−B−P Rings B₂P₂F_nH_8−n with n = 0, 1, 2, 4