Experimental structural and conformational studies of carbonyl molecules in the ground and lower excited states

Godunov, I. A.; Yakovlev, N. N.

doi:10.1007/bf02578062

Cited by 22 publications

(31 citation statements)

References 110 publications

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“…Energy gaps between ground and first excited singlet and triplet states of aliphatic and halogen-substituted carbonyls are of order of 20,000 -40,000 cm Ϫ1 and singlettriplet splitting between S 1 and T 1 states is about 2,000 -3,000 cm Ϫ1 (Ref. 4). The main active space (AS) used contains six electrons distributed over five orbitals, we denote it as .…”

Section: Methodsmentioning

confidence: 99%

“…Although experimental data are rather detailed for some systems [4], the structure and dynamics of the carbonyl molecules in the excited electronic states could not be considered a solved problem, and one may use reliable quantum-chemical calculation to fill in the gaps in our knowledge. There are a lot of approaches that could be used nowadays in calculations of parameters of the molecules in the excited electronic states, but, currently, we are far from understanding of their accuracy.…”

Section: Introduction Smentioning

confidence: 99%

“…It was proved experimentally for H 2 CO [1], HFCO [2], HClCO [3], and wide variety of other aliphatic carbonyls (for review, see Ref. [4]) that electronic excitation from the ground (S 0 ) to the lowest excited singlet (S 1 ) and triplet (T 1 ) states results in lengthening of CAO distance and pyramidalization of the carbonyl fragment planar in S 0 state.…”

Section: Introduction Smentioning

confidence: 99%

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Molecular parameters of tetraatomic carbonyls X₂CO and XYCO (X, Y = H, F, Cl) in the ground and lowest excited electronic states, part 1: A test ofab initiomethods

Bokarev

Dolgov

Bataev

et al. 2008

Int J of Quantum Chemistry

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Section: Methodsmentioning

confidence: 99%

Section: Introduction Smentioning

confidence: 99%

Section: Introduction Smentioning

confidence: 99%

See 1 more Smart Citation

Molecular parameters of tetraatomic carbonyls X₂CO and XYCO (X, Y = H, F, Cl) in the ground and lowest excited electronic states, part 1: A test ofab initiomethods

Bokarev

Dolgov

Bataev

et al. 2008

Int J of Quantum Chemistry

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“…The stretching (C=O) and bending (CCO) vibration frequencies of the conformers of DFE are sharply decreased upon TI~S 0 electronic excitation of the cis conformer, which is consistent with the data for other carbonyl compounds. 2 The frequencies given in Table 2 were determined within the framework of the classical harmonic model. This model makes it possible to adequately describe only small-amplitude vibrations.…”

mentioning

confidence: 99%

Ab initio study of the structure of 2,2-difluoroethanal in the ground and lowest excited triplet electronic states

et al. 2000

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The molecular structure of 2.2-difluoroethanal ~,DFE) in the ground (S 0) and lowest excited triplet (Ti) electronic states was investigated by ab initio quantum-chemical methods.In the S O state, the DFE molecule exists as the only stable cis conformer. The Tle--S 0 electronic excitation is accompanied by the rotation of the top and the deviation of the carbonyl fragment from planarity. For the DFE molecule in the T I state, six minima corresponding to three pairs of enantiomers were found on the potential energy surface. Based on this potential energy surface, the problems on torsion and inversion nuclear motions were solved in the one-and two-dimensional approximations, and the interaction between these motions was revealed.Key words: ab initio quantum-chemical calculations, carbonyl compounds, geometric parameters, vibration frequencies, potentials of internal rotation and inversion, ground and excited electronic states.The structures of many conformationally flexible molecules of carbonyl compounds, which have symmetrical tops (C3v), in the ground state (So) and in the lowest excited singlet (Sz) and triplet (T0 electronic states have been studied. It was found that the St<--S 0 and Tt+-S 0 electronic excitations of these molecules are accompanied by rotations of tops and pyramidalization of carbonyl Fragments (though this is not necessarily the case). I-5 Systems with lower-symmetry tops remain poorly studied, and the data on these compounds are more ambiguous. 6 This gave impetus to our studies of the structures of RCHO molecules (R = CH2C1 or CHF 2) in the S 0, S l, and T 1 states by molecular spectroscopy and quantum chemistry.In this work, we report the results of ab initio studies of the conformational behavior of the 2,2-difluoroethanal molecule (DFE; CHF2CHO) in the S o and Ti states. Most attention was given to large-amplitude nuclear motions, viz., to torsion (in the S o and T L states) and inversion (in the T t state) motions, for which one-and two-dimensional vibrational problems were solved.Taking into account our experience in investigations of molecules of carbonyl compounds in the ground and lowest excited electronic states, 6-10 we carried out calculations for the DFE molecule with the use of the restricted (RHF) and unrestricted (UHF) Hartree--Fock methods, the second-order M611er--Plesset perturbation theory (MP2), and the multiconfigurational method of the self-consistent field (the CASSCF technique) with the active space including molecular orbitals, which are close to frontier orbitals and are localized predominantly on the carbonyl fragment, via,., OCO, rr.co, no, rtCO*+ and ~co* (CASSCF(6e-SMO)). The principal calculations were carried out with the 6-31G** basis set. The correctness of the results was estimated by the configuration interaction method taking into account single and double excitations (CISD) and with the use of larger AO basis sets. The structure of the DFE molecule in the S O state was also studied by the density functional theory (DFT). The calculations were carried o...

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“…In particular, it has been found that excitation of molecules of nitroso compounds with C3v top symmetry (CR3, R = H, F) from the ground (So) to the lowest excited singlet (SI) electronic state causes a transition from an eclipsed (with respect to R and O atoms) equilibrium conformation to a staggered one. A similar picture is also observed for the molecules of carbonyl compounds, i, 3 Much less clear are the results obtained for the molecules of nitroso compounds with C s top symmetry (CCIF 2 and CCI2F), z though the structure of the CCIF2NO molecule has been studied in detail using several spectroscopic methods, viz., I R spectroscopy, 4…”

mentioning

confidence: 65%

The structure of CX2YNO (X, Y=F, Cl) molecules in the ground and lowest excited singlet electronic states

1999

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Ab initio quantum-chemical calculations of equilibrium geometric parameters, vibrational frequencies, and potentials of internal rotation for CCIF2NO and CCI2FNO molecules in the ground (So) and lowest excited singlet (Sj) electronic states were performed. The results of calculations were compared with experimental data. A new interpretation of experimental spectra of the CCIF2NO molecule was suggested.

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Experimental structural and conformational studies of carbonyl molecules in the ground and lower excited states

Cited by 22 publications

References 110 publications

Molecular parameters of tetraatomic carbonyls X₂CO and XYCO (X, Y = H, F, Cl) in the ground and lowest excited electronic states, part 1: A test ofab initiomethods

Molecular parameters of tetraatomic carbonyls X₂CO and XYCO (X, Y = H, F, Cl) in the ground and lowest excited electronic states, part 1: A test ofab initiomethods

Ab initio study of the structure of 2,2-difluoroethanal in the ground and lowest excited triplet electronic states

The structure of CX2YNO (X, Y=F, Cl) molecules in the ground and lowest excited singlet electronic states

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Experimental structural and conformational studies of carbonyl molecules in the ground and lower excited states

Cited by 22 publications

References 110 publications

Molecular parameters of tetraatomic carbonyls X2CO and XYCO (X, Y = H, F, Cl) in the ground and lowest excited electronic states, part 1: A test ofab initiomethods

Molecular parameters of tetraatomic carbonyls X2CO and XYCO (X, Y = H, F, Cl) in the ground and lowest excited electronic states, part 1: A test ofab initiomethods

Ab initio study of the structure of 2,2-difluoroethanal in the ground and lowest excited triplet electronic states

The structure of CX2YNO (X, Y=F, Cl) molecules in the ground and lowest excited singlet electronic states

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Molecular parameters of tetraatomic carbonyls X₂CO and XYCO (X, Y = H, F, Cl) in the ground and lowest excited electronic states, part 1: A test ofab initiomethods

Molecular parameters of tetraatomic carbonyls X₂CO and XYCO (X, Y = H, F, Cl) in the ground and lowest excited electronic states, part 1: A test ofab initiomethods