Thermal and CO-laser induced rotamerization of CH2ClCOOH in an argon matrix

Kulbida, A.; Носов, А. П.

doi:10.1016/0022-2860(92)80235-a

Cited by 16 publications

(10 citation statements)

References 8 publications

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“…However, previously two bands at 596 and at 526 cm-* were observed for this conformer in Ar. 5 In agreement with our normal-coordinate calculations the former band was assigned to OH torsion. The latter was assigned to C = O rock.…”

Section: Discussionsupporting

confidence: 69%

Matrix isolation infrared and ab initio studies on conformers of fluoroacetic and chloroacetic acid

Nieminen¹,

Pettersson²,

Räsänen³

1993

J. Phys. Chem.

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The infrared spectra of matrix isolated fluoroacetic acid and chloroacetic acid were studied in solid Ar, Kr, and Xe matrices. The energies and spectra of possible conformers of fluoroacetic acid and chloroacetic acid were simulated by extensive ab initio calculations at the MP2/6-3 1 1G** (energies, geometries), MP2/6-3 1G** (barriers), and MP2/4-3 lG* (numerical frequencies) levels. The present calculations propose the existence of four distinct conformers. For fluoroacetic acid the two lowest energy conformers, i.e., Tt and Ct, were found to be present after deposition of the solids. These conformers differ by 180' rotation of the fluoromethyl group and for both conformers the carboxylic hydrogen atom is in cis position with respect to the C = O bond. In agreement with the experimental results, the ab initio calculated energy difference between Tt and Ct is ca. 1 kJ mol-', and the barrier for Tt -Ct interconversion is ca. 13 kJ mol-'. For chloroacetic acid three conformers were identified in the matrix spectra. The lowest energy form Tt and C, symmetry. The second lowest energy conformer Gt differs from Tt by rotation of the chloromethyl group about the C-C bond (dihedral angle C1-C-C-0 = 7 7 O ) . The observed data and the calculations predict consistently a barrier of ca. 5 kJ mol-1 for this interconversion. For both conformers the carboxylic hydrogen atom is in cis position with respect to the C=O bond. The third observed conformer is Cc with intramolecular hydrogen bonding C1-H.A normal coordinate analysis based on the ab initio calculated force field is presented for observed conformers and compared with the experimental spectra. The similarities with related molecules are discussed.

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Section: Discussionsupporting

confidence: 69%

Matrix isolation infrared and ab initio studies on conformers of fluoroacetic and chloroacetic acid

Nieminen¹,

Pettersson²,

Räsänen³

1993

J. Phys. Chem.

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“…[10][11][12] Nevertheless, it should be emphasized that the elementary mechanism of IR-induced rotamerization is far from being completely understood. For instance, direct coupling of the excited overtone levels with the torsional manifold is a very high-order process, thus quite improbable.…”

Section: Figurementioning

confidence: 99%

“…3 It has repeatedly been reported for other carboxylic acid monomers that selective excitation of the OH stretching vibrations are of great utility to study conformational isomerization processes in this type of compound. [10][11][12] Furthermore, contrary to UV irradiation, IR irradiation does not usually lead to decomposition of the matrix-isolated molecules. Because the IR irradiation carried out in the previous study on oxalic acid was not selective, we decided to submit this compound to a new investigation, where selective narrowband and tunable IR irradiation was used, to better characterize the observed isomerization processes and, in particular, to search for other conformational species.…”

Section: Introductionmentioning

confidence: 99%

Infrared-Induced Rotamerization of Oxalic Acid Monomer in Argon Matrix

Maçôas¹,

Fausto²,

Pettersson³

et al. 2000

J. Phys. Chem. A

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Infrared-induced conformational isomerization of oxalic acid monomer isolated in an argon matrix at 7.5 K was studied by infrared spectroscopy. For the first time, three conformational states of this molecule were identified experimentally and their vibrational spectra are assigned. In good agreement with density functional theory predictions, all the observed conformers exhibit a trans OdC-CdO axis, differing in the relative conformation of their O-C-O-H axes. In the most stable conformer (belonging to the C 2h symmetry point group), two intramolecular OH‚‚‚Od hydrogen bonds are present. The second (C s ) most stable conformer shows a single OH‚‚‚Od bond, and the third one (C 2h ) does not exhibit any intramolecular hydrogen bond. Using narrowband tunable irradiation in the near-infrared region it was possible to promote very efficiently conformer interconversions, which was followed spectroscopically.

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“…Together with solid state vibrational spectroscopic studies undertaken on pure substances, MIS can provide detailed information on vibrational signature of monomeric species and aggregates of different sizes and on the intermolecular interactions that are operating in these later, in particular, hydrogen bonding [7,8].…”

Section: Introductionmentioning

confidence: 99%

Structure elucidation and photochemistry of substituted carboxylic compounds by low temperature matrix-isolation and solid state vibrational spectroscopy

Fausto

Maçôas

Kulbida

1999

Journal of Molecular Structure

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Molecular structures and chemical reactivity (aggregation, phase transitions and photochemistry) of a series of substituted carboxylic acids were studied by low temperature matrix isolation and solid state vibrational spectroscopy, complemented by ab initio molecular orbital calculations. The conformational preferences exhibited by the isolated molecules of the systems under study are analyzed, and the effects of aggregation, temperature change and irradiation are discussed.

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Thermal and CO-laser induced rotamerization of CH2ClCOOH in an argon matrix

Cited by 16 publications

References 8 publications

Matrix isolation infrared and ab initio studies on conformers of fluoroacetic and chloroacetic acid

Matrix isolation infrared and ab initio studies on conformers of fluoroacetic and chloroacetic acid

Infrared-Induced Rotamerization of Oxalic Acid Monomer in Argon Matrix

Structure elucidation and photochemistry of substituted carboxylic compounds by low temperature matrix-isolation and solid state vibrational spectroscopy

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