Assignment Of Fundamental Vibrational Frequencies Research Articles

Syntheses and Structural Characterizations of the Cl(V) Coordination Complex, [O2Cl(FXeF)2][AsF6], and β-[ClO2][AsF6

The synthesis and structural characterization of the first Cl(V) coordination complex of XeF2, [O2Cl(FXeF)2][AsF6], is described. The reaction of α-[ClO2][AsF6] with XeF2 at −78 °C in anhydrous HF (aHF) solvent yields [O2Cl(FXeF)2][AsF6], a rare example of noble-gas difluoride coordination to a main-group Lewis acid center. The low-temperature (LT) phase of β-[ClO2][AsF6] was obtained by recrystallization of α-[ClO2][AsF6] from aHF solvent at –10 °C. The compounds were characterized by LT single-crystal X-ray diffraction and LT Raman spectroscopy. Quantum-chemical calculations were carried out for the model gas-phase ([O2Cl(FXeF)2][AsF6]2)− anion to aid in the assignments of fundamental vibrational frequencies and 35/37Cl isotope shifts for [O2Cl(FXeF)2][AsF6] and to assess its chemical bonding by use of an NBO analysis. The [O2Cl(FXeF)2]+ cations and [AsF6]− anions of [O2Cl(FXeF)2][AsF6] are intimate ion-pairs with secondary Cl---FAs and Cl---FXe bonds that are significantly shorter than the sums of the Cl and F van der Waals radii, and are consistent with noncovalent σ-hole bonding. MEPS and NBO analyses were also carried out for the gas-phase [XO2]+ (X = Cl, Br, I) cations.

Structural, spectral, electronic, and molecular docking investigations on N,N‐dimethyl‐2‐[(1E)‐({[(methylsulfanyl)methanethioyl]amino}imino)methyl]aniline

AbstractIn this research, a joint theoretical and experimental investigation was performed on the structural and spectral data (FT‐IR, Laser‐Raman, NMR, and UV–vis) of N,N‐dimethyl‐2‐[(1E)‐({[(methylsulfanyl)methanethioyl]amino}imino)methyl]aniline molecule. The theoretical electronic structure analyses were fulfilled by the density functional theory at the B3LYP level with the 6‐311++G(d,p) basis set in the gas phase of the isolated compound at the ground state. The vibrational works were analyzed in terms of potential energy distribution analysis to make the assignments of fundamental vibrational frequencies and the assigned modes of the title compound were compared with the reported experimental vibrational data. Later, Hirshfeld surface analysis over crystalline structure of the title compound was made to define the possible inter‐molecular interactions. In addition, the HOMO (highest occupied molecular orbital), LUMO (lowest unoccupied molecular orbital), UV–vis, and molecular electrostatic potential analyses were done. The molecular docking investigation was done in order to analyze the presence of interactions between the title ligand compound and the receptor protein 2VN0.

Gaseous Phase Heat Capacity of Benzoic Acid

The gaseous phase heat capacity of benzoic acid (BA) was proven using the experimental technique called the “in vacuum sublimation/vaporization Calvet microcalorimetry drop method”. To overcome known experimental shortfalls, the gaseous phase heat capacity of BA monomer was estimated by ab initio calculations and compared with experimental results. Gaseous phase heat capacities of BA were directly derived via calculated harmonic frequencies obtained by density functional theory (DFT) (B3LYP, BLYP, BP86, with 6-311++G(d,p), TZVP, cc-pVTZ basis sets) and the second-order Møller−Plesset theory, MP2/6-311++G(d,p). To increase the accuracy of estimation of the thermal properties, a procedure based on the calculation of the heat capacity from quantum chemical calculations in combination with a heat capacity balance of isodesmic reactions is described and applied to calculate the gaseous phase heat capacity, Cp,m, of the monomeric species over the temperature range of (298.15 to 600) K. The gaseous phase thermodynamic properties of the monomeric form of the BA were also derived from the assignment of the fundamental vibrational frequencies using experimental IR spectra. An excellent agreement among the experimental gaseous phase heat capacities, the results obtained using the proposed ab initio procedure, and the results derived from the assignment of fundamental vibrational frequencies was found. The results for the monomeric form of the BA, directly or indirectly obtained, and conclusions of this work strongly support the thesis that the gaseous phase heat capacity data as currently found in the literature are underestimated to the order of 20 %.

Density functional theory study of vibrational spectra, 6: assignment of fundamental vibrational frequencies of benzene isomers: Dewar benzene, benzvalene, trimethylenecyclopropane, prismane, and 3,4-dimethylenecyclobutene

The molecular structures and vibrational spectra of Dewar benzene, benzvalene, trimethylenecyclopropane, prismane and 3,4-dimethylenecyclobutene have been investigated by density functional theory using Becke's exchange with Lee—Yang—Parr's correlation functionals and the 6–31G∗ basis set. Both the calculated structural parameters and vibrational frequencies are in good agreement with available experimental data. On the basis of the agreement between the calculated and experimental results, assignments of fundamental vibrational frequencies of Dewar benzene, benzvalene, and trimethylenecyclopropane were examined and some reassignments are proposed. The calculations also predict prominent IR and Raman spectral features of prismane and 3,4-dimethylenecyclobutene, which can assist experimental identification of these compounds and the assignment of observed spectral features when they are available.

Density functional theory study of vibrational spectra, 6: assignment of fundamental vibrational frequencies of benzene isomers: Dewar benzene, benzvalene, trimethylenecyclopropane, prismane, and 3,4-dimethylenecyclobutene

Density functional theory study of vibrational spectra, 6: assignment of fundamental vibrational frequencies of benzene isomers: Dewar benzene, benzvalene, trimethylenecyclopropane, prismane, and 3,4-dimethylenecyclobutene

Vibrational spectra and thermodynamic functions of allyl acetate

Raman spectrum of allyl acetate molecule has been photographed in liquid phase using 4358 Å line of mercury arc as the exciting line. Infrared absorption spectrum of the molecule has been recorded in liquid phase in the frequency range 200–4000 cm−1. Both the spectra have been analysed to identify the fundamental frequencies. AssumingC s symmetry, the observed fundamental frequencies have been assigned to various modes of vibration and compared with the frequencies of allyl halides and acetic acid. On the basis of present assignments of fundamental vibrational frequencies and assumed approximate structural parameters of the molecule, thermodynamic functions have been computed.

Infrared absorption spectra of deuterated vinyl fluorides

Infrared absorption spectra of vinyl fluoride and its seven deuterated derivatives have been taken. The assignment of fundamental vibrational frequencies for vinyl fluoride originally given by T orkington and T hompson must be slightly modified. A final assignment for all eight isotopic species is suggested.

Vibrational Spectra and Calculated Thermodynamic Properties of Ethyl Chloride and 1,1-Dichloroethane

The infrared absorption spectra of H3C–CH2Cl and H3C–CHCl2 in the gaseous and liquid states have been obtained in the region from 2 to 38μ with the aid of LiF, NaCl, KBr, and KRS-5 prisms. The Raman spectra of the liquids have been photographed with a 3-prism glass spectrograph of linear dispersion 15 A/mm at 4358A. Relative intensities and depolarization ratios have been measured for most of the Raman bands. Complete assignments of fundamental vibrational frequencies have been made, the spectra have been interpreted in detail, and thermodynamic functions have been calculated for the compounds in the gaseous state.

Vibrational Spectra and Calculated Thermodynamic Properties of 1,1,1,2-Tetrachloroethane and Pentachloroethane*

The infrared absorption spectra of CCl3CH2Cl in the gaseous and liquid states and of liquid CCl3CHCl2 have been obtained in the region from 2 to 38μ with the aid of LiF, NaCl, KBr and KRS-5 prisms. The Raman spectra of these compounds in the liquid state have been photographed with a three-prism glass spectrograph of linear dispersion 15 A/mm at 4358A. Relative intensities and depolarization ratios have been measured for most of the Raman bands. Complete assignments of fundamental vibrational frequencies have been made, the spectra have been interpreted in detail, and thermodynamic functions have been calculated for the compounds in the gaseous state.

Vibrational Spectra of Fluorinated Aromatics. VIII. 1,4-Bis(trifluoromethyl)benzene

The infrared absorption of liquid 1,4-bis(trifluoromethyl) benzene has been obtained in the region 2–22μ with the aid of LiF, NaCl, and KBr prisms. The Raman spectrum has been photographed with a three-prism glass spectrograph of linear dispersion 15A/mm at 4358A. A nearly complete assignment of fundamental vibration frequencies is given, and the spectra are interpreted in detail.

Vibrational Spectra of Fluorinated Aromatics. VII. 1,2,4-Trifluorobenzene

The infrared absorption spectrum of liquid 1,2,4-trifluorobenzene has been obtained in the region 2–38μ with the aid of LiF, NaCl, KBr, and KRS−5 prisms. The Raman spectrum of the liquidh as been photographed with a three-prism glass spectrograph of linear dispersion 15A/mm at 4358A, and depolarization ratios have been measured for the stronger Raman bands. A complete assignment of fundamental vibration frequencies is given, and the spectra are interpreted in detail.

Vibrational Spectra of Fluorinated Aromatics. IX. p-Fluorotoluene

The infrared absorption spectrum of liquid p-fluorotoluene has been obtained in the region 2–38μ with the aid of LiF, NaCl, KBr, and KRS−5 prisms. The stronger bands of the gas phase have been scanned with NaCl and KBr prisms. The Raman spectrum of the liquid has been photographed with a three-prism glass spectrograph of linear dispersion 15A/mm at 4358A. A complete assignment of fundamental vibration frequencies is given, and the spectra are interpreted in detail.

Vibrational Spectra of Fluorinated Aromatics. III. 1,4-Difluorobenzene

The infrared absorption spectra of gaseous and liquid 1,4-difluorobenzene have been obtained in the regions 2–22μ and 2–38μ, respectively, with the aid of LiF, NaCl, KBr, and KRS−5 prisms. The Raman spectrum of the liquid phase has been photographed with a three-prism glass spectrograph of linear dispersion 15A/mm at 4358A. Depolarization ratios have been measured for the stronger Raman bands. A complete assignment of fundamental vibration frequencies has been made, and the spectra have been interpreted in detail. The nonplanar frequencies have been calculated with the aid of force constants determined for related molecules

Vibrational Spectra of Fluorinated Aromatics. V. 1,3-Difluorobenzene

The infrared absorption spectrum of liquid 1,3-difluorobenzene has been obtained in the region 2–22μ with the aid of LiF, NaCl, and KBr prisms. The contours of the strong infrared bands of the gaseous phase have also been observed in the region 5–22μ. The Raman spectrum of the liquid has been photographed with a three-prism glass spectrograph of linear dispersion 15 A/mm at 4358A, and depolarization ratios have been measured for the stronger Raman bands. A complete assignment of fundamental vibration frequencies is given and the spectra are interpreted in detail.

Vibrational Spectra of Fluorinated Aromatics. VI. Fluorobenzene

The infrared absorption spectra of gaseous and liquid fluorobenzene have been obtained in the regions 2–22μ and 2–38μ, respectively, with the aid of LiF, NaCl, KBr, and KRS−5 prisms. The Raman spectrum of the liquid phase has been photographed with a three-prism glass spectrograph of linear dispersion 15 A/mm at 4358A. A complete assignment of fundamental vibration frequencies is given, and the spectra are interpreted in detail.

Vibrational Spectra of Fluorinated Aromatics. IV. 1,2,4,5-Tetrafluorobenzene

The infrared absorption spectra of gaseous and liquid 1,2,4,5-tetrafluorobenzene have been obtained in the region 2–22μ with the aid of LiF, NaCl, and KBr prisms. The Raman spectrum of the liquid phase has been photographed with a three-prism glass spectrograph of linear dispersion 15 A/mm at 4358A. Relative intensities and depolarization ratios have been measured for the stronger Raman bands. A complete assignment of fundamental vibration frequencies is made and the spectra are interpreted in detail. The values of the nonplanar fundamental frequencies are checked by normal coordinate analysis.

Infrared and Raman Spectra of Fluorinated Ethylenes. V. Hexafluoropropene

The infrared absorption spectrum of gaseous CF2:CF–CF3 has been obtained in the region from 2 to 38μ, with the aid of LiF, NaCl, KBr, and KRS-5 prisms. The Raman spectrum of both the gaseous and the liquid phase has been photographed with a three-prism glass spectrograph of linear dispersion 15 A/mm at 4358A, and depolarization ratios have been measured for the stronger bands. A complete assignment of fundamental vibrational frequencies is given, although four of the twenty-one fundamentals must be regarded as uncertain. The spectra are interpreted in detail.

Infrared and Raman Spectra of Fluorinated Ethylenes. IV. 1,1-Difluoro-2-chloroethylene

The infrared absorption spectra of gaseous and liquid CF2:CHCl have been obtained in the regions 2–22μ and 2–38μ, respectively, with the aid of LiF, NaCl, KBr, and KRS-5 prisms. The Raman spectrum of the liquid phase has been photographed with a three-prism glass spectrograph of linear dispersion 15 A/mm at 4358A. Relative intensities and depolarization ratios have been measured for the stronger Raman bands. A complete assignment of fundamental vibration frequencies is given, the spectra are interpreted in detail, and thermodynamic functions are calculated for the temperature range 253–600°K.

The Raman Effect of Vinylidene Chloride

The Raman spectrum of vinylidene chloride is reported. An assignment of fundamental vibrational frequencies is made and the overtone and combination frequencies interpreted. A method of accurately marking faint Raman lines for measurement is described.