Structure and conformation of gaseous butyronitrile: C–H⋯π interaction?

Trætteberg, M.; Bakken, P.; Hopf, Henning

doi:10.1016/s0022-2860(00)00632-3

Cited by 24 publications

(33 citation statements)

References 11 publications

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“…The values obtained for the CBN bond are in agreement with previous theoretical studies [6,7], see Table II. However, we also find that they are slightly larger than the values observed experimentally [6].…”

Section: Structural Variationsupporting

confidence: 92%

“…8 and 61.4 , were obtained in previous works at the MP2 level using the 6-311þþG(2d,2p) [6] and the 6-311þG(2df,2pd) [7] basis sets, respectively, see Table II. The experimental value found for this angle by gas electron diffraction [6] is 61.1 , in full agreement with the present result. A local minimum corresponding to the trans form of n-propyl cyanide is found for h 1 ¼ 180.0 and h 2 ¼ 180.1 , see Figure 3(b).…”

Section: Characterization Of Structuresmentioning

confidence: 99%

“…Traetteberg et al [6] using gas electron diffraction and ab initio calculations, concluded that the gauche form is dominant in the phase gas. These authors found a clear major abundance of the gauche over the trans form, in proportions 75/25% and 77/23% for their experimental and theoretical data, respectively.…”

Section: Structural Variationmentioning

confidence: 99%

“…On the other hand, more recent experimental and theoretical works have found the gauche form as the most stable [6,7]. Thus, Traetteberg et al [6] performed a molecular structure study using gas electron diffraction (GED). In this study, the authors established that the gauche conformer dominates in the conformational mixture.…”

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confidence: 99%

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Analysis of the nitrile and methyl torsional vibrations of n‐propyl cyanide in its S₀ electronic state

Castro

Muñoz‐Caro

Niño

2010

Int J of Quantum Chemistry

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This work presents a structural and vibrational theoretical study of n-propyl cyanide as a function of the nitrile and methyl torsional modes. A potential energy hypersurface is built at the MP4(SDQ)/aug-cc-pVTZ//MP2/aug-cc-pVTZ theory level. The equilibrium structure is found in a gauche conformation. Another minimum is found for the trans form. The maximum appears in a cis conformation. For the first time, the interconversion barriers between the different forms are calculated. A twodimensional anharmonic vibrational Hamiltonian is built for the nitrile and methyl torsional modes. We find the vibrational energy levels to organize in two stacks associated to the gauche and trans forms. Fundamental frequencies of 113.12 and 220.54 cm À1 are predicted for the nitrile and methyl torsions in the equilibrium, gauche, conformer. In addition, we find symmetry allowed transitions between the gauche and trans energy levels stacks. The lowest transition is predicted to appear at 24.49 cm À1.

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Section: Structural Variationsupporting

confidence: 92%

Section: Characterization Of Structuresmentioning

confidence: 99%

Section: Structural Variationmentioning

confidence: 99%

mentioning

confidence: 99%

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Analysis of the nitrile and methyl torsional vibrations of n‐propyl cyanide in its S₀ electronic state

Castro

Muñoz‐Caro

Niño

2010

Int J of Quantum Chemistry

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“…Wlodarczak et al (1988) extended the measurements into the millimeter region, measured the dipole moment components, and determined from intensity measurements that the anti conformer is lower in energy than gauche by 1.1 ± 0.3 kJ mol −1 (or 92 ± 25 cm −1 or 132 ± 36 K), in line with the estimate by Hirota (1962) that the energy difference between the two is small, perhaps less than 1 kcal mol −1 (or 350 cm −1 or 504 K). However, Charles et al (1976) and Traetteberg et al (2000) determined from earlier infrared (IR) spectroscopy of solid, liquid, and gaseous samples and from electron diffraction of a gaseous sample that the gauche conformer is lower in energy. Durig et al (2001) used IR spectroscopy of n-PrCN dissolved in liquid Xenon (−60 to −100 • C) to determine that the gauche conformer is lower than anti by 0.48 ± 0.04 kJ mol −1 (or 40 ± 3 cm −1 or 58 ± 4 K).…”

Section: Introductionmentioning

confidence: 99%

Laboratory spectroscopic study and astronomical detection of vibrationally excitedn-propyl cyanide

Müller

Walters

Wehres

et al. 2016

A&A

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Context. We performed a spectral line survey called Exploring Molecular Complexity with ALMA (EMoCA) toward Sagittarius B2(N) between 84.1 and 114.4 GHz with the Atacama Large Millimeter/submillimeter Array (ALMA) in its Cycles 0 and 1. We determined line intensities of n-propyl cyanide in the ground vibrational states of its gauche and anti conformers toward the hot molecular core Sagittarius B2(N2) which suggest that we should also be able to detect transitions pertaining to excited vibrational states. Aims. We wanted to determine spectroscopic parameters of low-lying vibrational states of both conformers of n-propyl cyanide to search for them in our ALMA data. Methods. We recorded laboratory rotational spectra of n-propyl cyanide in two spectral windows between 36 and 127 GHz. We searched for emission lines produced by these states in the ALMA spectrum of Sagittarius B2(N2). We modeled their emission and the emission of the ground vibrational states assuming local thermodynamic equilibrium (LTE). Results. We have made extensive assignments of a-and b-type transitions of the four lowest vibrational states of the gauche conformer which reach J and K a quantum numbers of 65 and 20, respectively. We assigned mostly a-type transitions for the anti conformer with J and K a quantum numbers up to 48 and 24, respectively. Rotational and Fermi perturbations between two anti states allowed us to determine their energy difference. The resulting spectroscopic parameters enabled us to identify transitions of all four vibrational states of each conformer in our ALMA data. The emission features of all states, including the ground vibrational state, are wellreproduced with the same LTE modeling parameters, which gives us confidence in the reliability of the identifications, even for the states with only one clearly detected line. Conclusions. Emission features pertaining to the highest excited vibrational states of n-propyl cyanide reported in this work have been identified just barely in our present ALMA data. Features of even higher excited vibrational states may become observable in future, more sensitive ALMA spectra to the extent that the confusion limit will not have been reached. The 13 C isotopomers of this molecule are expected to be near the noise floor of our present ALMA data. We estimate that transitions of vibrationally excited iso-propyl cyanide or aminoacetonitrile, for example, are near the noise floor of our current data as well.

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Structure and relative energies of the conformers of n‐butyl cyanide and 5‐hexynenitrile

Atticks

Bohn

Michels

2002

Int J of Quantum Chemistry

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ABSTRACT:The microwave spectrum of n-butyl cyanide and 5-hexynenitrile (5-cyano-1-pentyne) reveal the presence of three conformers that have been characterized. Each of these molecules can exist in anti-anti (AA), anti-gauche (AG), gauche-anti (GA), gauchegauche (GG trans), and gauche-gaucheЈ (GGЈ cis) conformations. The first three conformers have been observed experimentally and characterized in both compounds. In previous studies, we examined the microwave spectrum of the related n-butyl acetylene molecule and observed and characterized the mono-13 C-isotopomers of the AA and GA forms of nbutyl acetylene as well as the AG form, albeit at lower intensity. The GG conformers, in both cis and trans arrangements have not been identified to date for these molecules. The structures and energies of the five possible conformers of each molecule have been determined through quantum mechanical calculations at the HF and MP2 levels of theory, using both double-zeta [6-31G(d,p)] and triple-zeta [6-311ϩG(d,p)] basis sets. The calculated energies of the five possible conformers of each molecule are close, and a change in the relative stability order of these conformers is found at different levels of theory. For n-butyl cyanide and n-butyl acetylene, the GA form lies lowest in energy, both experimentally and at the MP2 level of theory. For 5-hexynenitrile, the GG trans form is predicted to lie lowest in energy. The predicted conformer stability order is in agreement with a model of a net attractive electrostatic interaction between the -electron densities and the closest hydrogen on the next-nearest-neighbor carbon.

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Structure and conformation of gaseous butyronitrile: C–H⋯π interaction?

Cited by 24 publications

References 11 publications

Analysis of the nitrile and methyl torsional vibrations of n‐propyl cyanide in its S₀ electronic state

Analysis of the nitrile and methyl torsional vibrations of n‐propyl cyanide in its S₀ electronic state

Laboratory spectroscopic study and astronomical detection of vibrationally excitedn-propyl cyanide

Structure and relative energies of the conformers of n‐butyl cyanide and 5‐hexynenitrile

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Structure and conformation of gaseous butyronitrile: C–H⋯π interaction?

Cited by 24 publications

References 11 publications

Analysis of the nitrile and methyl torsional vibrations of n‐propyl cyanide in its S0 electronic state

Analysis of the nitrile and methyl torsional vibrations of n‐propyl cyanide in its S0 electronic state

Laboratory spectroscopic study and astronomical detection of vibrationally excitedn-propyl cyanide

Structure and relative energies of the conformers of n‐butyl cyanide and 5‐hexynenitrile

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Product

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Analysis of the nitrile and methyl torsional vibrations of n‐propyl cyanide in its S₀ electronic state

Analysis of the nitrile and methyl torsional vibrations of n‐propyl cyanide in its S₀ electronic state