Infrared gas-phase intensity measurements, polar tensors and effective charges of trans-difluoro-and trans-dichloroethylene

Kagel, R. O.; Powell, D. L.; Hopper, M. J.; Overend, John; Ramos, Mozart N.; Bassi, Adalberto Bono Maurizio Sacchi; Bruns, Roy E.

doi:10.1021/j150647a040

Cited by 26 publications

(21 citation statements)

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“…As for hexafluorobenzene the inplane and out-of-plane intensities are both small, 4.7 and 4.4 km mol −1 , respectively. Consistent with these calculations, the observed out-of-plane CH bending intensities in trans-C 2 H 2 F 2 (56.7 km mol −1 ) 26 and 1,1-C 2 H 2 F 2 (60.3 km mol −1 ), 27 are much larger than their CF counterparts (12.7 and 0.3 km mol −1 , respectively).…”

Section: Calculationssupporting

confidence: 80%

Quantum Theory of Atoms in Molecules Charge–Charge Transfer–Dipolar Polarization Classification of Infrared Intensities

et al. 2017

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Fundamental infrared vibrational transition intensities of gas-phase molecules are sensitive probes of changes in electronic structure accompanying small molecular distortions. Models containing charge, charge transfer, and dipolar polarization effects are necessary for a successful classification of the C-H, C-F, and C-Cl stretching and bending intensities. C-H stretching and in-plane bending vibrations involving sp carbon atoms have small equilibrium charge contributions and are accurately modeled by the charge transfer-counterpolarization contribution and its interaction with equilibrium charge movement. Large C-F and C═O stretching intensities have dominant equilibrium charge movement contributions compared to their charge transfer-dipolar polarization ones and are accurately estimated by equilibrium charge and the interaction contribution. The C-F and C-Cl bending modes have charge and charge transfer-dipolar polarization contribution sums that are of similar size but opposite sign to their interaction values resulting in small intensities. Experimental in-plane C-H bends have small average intensities of 12.6 ± 10.4 km mol owing to negligible charge contributions and charge transfer-counterpolarization cancellations, whereas their average out-of-plane experimental intensities are much larger, 65.7 ± 20.0 km mol, as charge transfer is zero and only dipolar polarization takes place. The C-F bending intensities have large charge contributions but very small intensities. Their average experimental out-of-plane intensity of 9.9 ± 12.6 km mol arises from the cancellation of large charge contributions by dipolar polarization contributions. The experimental average in-plane C-F bending intensity, 5.8 ± 7.3 km mol, is also small owing to charge and charge transfer-counterpolarization sums being canceled by their interaction contributions. Models containing only atomic charges and their fluxes are incapable of describing electronic structure changes for simple molecular distortions that are of interest in classifying infrared intensities. One can expect dipolar polarization effects to also be important for larger distortions of chemical interest.

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Section: Calculationssupporting

confidence: 80%

Quantum Theory of Atoms in Molecules Charge–Charge Transfer–Dipolar Polarization Classification of Infrared Intensities

et al. 2017

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“…cDCLE and tDCLE and their deuterium isotopomers have been well studied by low-resolution vibrational spectroscopy. Ramsay and Bernstein did a comprehensive study that yielded assignments of most of the vibrational fundamentals. , Hopper and co-workers followed that study with an investigation of infrared intensities of both isomers . Recently, a higher level analysis of the intensities has been contributed by Bruns and co-workers …”

Section: Introductionmentioning

confidence: 99%

A Complete Structure of trans-1,2-Dichloroethylene from High-Resolution Infrared Spectroscopy

Craig¹,

Appleman²,

Barnes³

et al. 1998

J. Phys. Chem. A

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The rotational structure in the C-type bands of the high-resolution (0.002 cm-1), gas-phase infrared spectra of four isotopomers of trans-1,2-dichloroethylene has been analyzed. The C-type band, which is due to CH or CD out-of-plane flapping, is at 897.949 82 (3) cm-1 for the normal species with 35Cl2. For the 35Cl2 variants, the ground-state rotational constants in cm-1 are A = 1.747 268 (3), B = 0.051 570 5 (3), and C = 0.050 080 7 (3) for the normal species; A = 1.677 033 (2), B = 0.051 501 0 (2), and C = 0.049 954 0 (2) for the 13C2 species; and A = 1.181 144 7 (9), B = 0.051 540 7 (2), and C = 0.049 371 9 (2) for the d2 species. For the d 2-35Cl37Cl isotopomer, A = 1.180 765 (2), B = 0.050 164 9 (3), and C = 0.048 107 5 (3) cm-1. A substitution structure (r s) was fit and found to have r CH = 1.078 (4) Å, r CC = 1.305 (5) Å, r CCl = 1.740 (3) Å, αCCH = 125.3 (5) Å, and αCCl = 119.9 (4) Å. Structural adjustments in going from the lower energy cis isomer to the higher energy trans isomer are discussed in the context of current qualitative theories of the cis effect.

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“…Overall, the off-diagonal terms in the potential energy distributions (PED) are smaller with our coordinates than with those used previously. 8,9 The initial scaling of the symmetry force constants was carried out on the B3LYP/tz and MP2/tz force constants, employing only frequency data. A very satisfactory fit was achieved using the nine scale factors listed in Table 6.…”

Section: Resultsmentioning

confidence: 99%

Vibrational and Quantum Chemical Studies of 1,2-Difluoroethylenes: Spectra of 1,2-¹³C₂H₂F₂ Species, Scaled Force Fields, and Dipole Derivatives

2002

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Infrared and Raman spectra are reported for cis and trans 1,2-13 C 2 H 2 F 2 . Quantum chemical calculations at B3LYP and MP2 levels have been made for cis and trans 1,2-difluoroethylenes, using 6-311G** and 6-311++G** bases. The resulting harmonic force fields for each compound were scaled with nine independent factors, using frequency data corrected, where necessary, for Fermi resonances and for liquid/gas shifts. The previously accepted assignments for ν 7 and ν 12 in the trans isomer are interchanged. Several scale factors for bending motions differ markedly between the cis and trans compounds. Centrifugal distortion constants observed with significant accuracy are predicted within 6%. Harmonic contributions to the vibrational dependence of the rotational constants and perpendicular amplitudes are calculated. The CdC and C-H bonds in the cis and trans isomers are essentially identical in respect to length, force constant, and isolated CH stretching frequency. However, the C-F bond is slightly stronger in the cis compound. A revised allocation of observed infrared intensity between the overlapping trans ν 7 and ν 12 bands is needed. Directions of ∂p/∂Q for the trans B u bands are given, which differ from those reported earlier. Magnitudes and directions of the bond dipole derivatives ∂µ/∂r for the CH and CF bonds are obtained from calculated atomic polar tensors. In both cis and trans isomers, the vector ∂µ/∂r CF lies within 17°of the bond direction, but for the CH bond, ∂µ/∂r is roughly perpendicular to the CH direction.

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Infrared gas-phase intensity measurements, polar tensors and effective charges of trans-difluoro-and trans-dichloroethylene

Cited by 26 publications

References 0 publications

Quantum Theory of Atoms in Molecules Charge–Charge Transfer–Dipolar Polarization Classification of Infrared Intensities

Quantum Theory of Atoms in Molecules Charge–Charge Transfer–Dipolar Polarization Classification of Infrared Intensities

A Complete Structure of trans-1,2-Dichloroethylene from High-Resolution Infrared Spectroscopy

Vibrational and Quantum Chemical Studies of 1,2-Difluoroethylenes: Spectra of 1,2-¹³C₂H₂F₂ Species, Scaled Force Fields, and Dipole Derivatives

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Infrared gas-phase intensity measurements, polar tensors and effective charges of trans-difluoro-and trans-dichloroethylene

Cited by 26 publications

References 0 publications

Quantum Theory of Atoms in Molecules Charge–Charge Transfer–Dipolar Polarization Classification of Infrared Intensities

Quantum Theory of Atoms in Molecules Charge–Charge Transfer–Dipolar Polarization Classification of Infrared Intensities

A Complete Structure of trans-1,2-Dichloroethylene from High-Resolution Infrared Spectroscopy

Vibrational and Quantum Chemical Studies of 1,2-Difluoroethylenes: Spectra of 1,2-13C2H2F2 Species, Scaled Force Fields, and Dipole Derivatives

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Vibrational and Quantum Chemical Studies of 1,2-Difluoroethylenes: Spectra of 1,2-¹³C₂H₂F₂ Species, Scaled Force Fields, and Dipole Derivatives