Hydrogen bonding in the gas phase: the infrared spectra of complexes of hydrogen fluoride with hydrogen cyanide and methyl cyanide

1971 ◽  
Vol 325 (1560) ◽  
pp. 133-149 ◽  
Keyword(s):  
Hydrogen Bond ◽  
Fine Structure ◽  
Gas Phase ◽  
Infrared Spectra ◽  
Low Frequency ◽  
Bending Vibration ◽  
Methyl Cyanide ◽  
Complete Assignment ◽  
Stretching Vibration ◽  
The Individual

The infrared spectra of the gas phase complexes HCN-HF, DCN-DF and four isotopic species of CH3CN-HF have been measured over the range 200 to 4000 cm -1 . Two bands have been observed, one associated with the stretching vibration of HF in the complex and the other with a bending vibration of the hydrogen bond itself. At higher resolution both bands show fine structure which has been interpreted as being a series of hot bands associated with transitions from excited levels of another low-frequency bending vibration of the hydrogen bond. In the first band the peaks are P branch bandheads in the individual hot bands and in the second band they are sharp Q branches. From temperature studies of these bands and from the effects of isotopic substitution on the spacing of the fine structure the frequency of the lower bending vibration has been determined. Further structure in the first band gives the frequency of the stretching vibration of the hydrogen bond itself. A complete assignment of all the vibrations associated with the hydrogen bond has therefore been made. From the frequencies of the two bending motions (555 and 70 cm -1 for the HCN-HF complex) values of the bending force constants have been calculated. Several anharmonic constants have also been measured and the effect of anharmonicity on the breadth of bands associated with the hydrogen bond is discussed.

Far Infrared Group Frequencies. V. Oximes and Aldoximes

1973 ◽  
Vol 27 (1) ◽  
pp. 22-26 ◽  
Author(s):  
S. M. Craven ◽  
F. F. Bentley ◽  
D. F. Pensenstadler
Keyword(s):  
Hydrogen Bond ◽  
Infrared Spectra ◽  
Low Frequency ◽  
Far Infrared ◽  
Torsional Vibrations ◽  
Lattice Vibrations ◽  
Dilute Solutions ◽  
Solid Samples ◽  
Bending Modes ◽  
Bond Stretch

The low frequency infrared spectra from 450 to 75 cm−1 of seven oximes and five aldoximes have been recorded for pure samples and for dilute solutions in cyclohexane. An intense characteristic band is present in the solution spectra at 367 ± 10 cm−1. This characteristic band shifts to 275 ± 10 cm−1 in the spectra of the OD compounds. The 367 ± 10 cm−1 and 275 ± 10 cm−1 bands are assigned to OH and OD torsional vibrations. A comparison of the solution spectra with spectra of the solid samples indicated that the OH … N hydrogen bond stretch of oximes and aldoximes occurs in 300 to 200 cm−1 region. Strong bands also are present in 140 to 100 cm−1 region which are due to OH … N bending modes or perhaps lattice vibrations.

Hydrogen bonding in the gas phase: the thermodynamic properties of hydrogen fluoride-ether complexes and their far infrared spectra

1971 ◽  
Vol 322 (1548) ◽  
pp. 137-146 ◽  
Keyword(s):  
Hydrogen Bonding ◽  
Gas Phase ◽  
Infrared Spectra ◽  
Equilibrium Constants ◽  
Far Infrared ◽  
Methyl Ethyl ◽  
Rotational Contour ◽  
Stretching Vibration ◽  
Conformational Rearrangements ◽  
Far Infrared Spectra

The equilibrium constants of gas-phase complexes of HF with dimethyl, methyl ethyl and diethyl ether have been measured at several temperatures using the Benesi-Hildebrand approximation on the absorption band of the HF stretching vibration in the complex. From these, values of Δ H of — 43, — 38 and — 30 kJ mol -1 respectively, have been determined. They are interpreted in terms of conformational rearrangements of the ethers when they form hydrogen bonds. The far infrared spectra of the complexes with both HF and DF have also been recorded and in each case a band observed at around 180 cm -1 which is assigned to the intermolecular stretching mode of vibration. For the complex between HF and dimethyl ether a rotational contour has been observed at about 10 cm -1 .

scholarly journals HIGH-RESOLUTION GAS PHASE THz SPECTROSCOPY OF THE CATECHOL LOW FREQUENCY MODES INVOLVING AN INTRAMOLECULAR HYDROGEN BOND

2021 ◽  
Author(s):  
Jonas Bruckhuisen ◽  
Arnaud Cuisset ◽  
Marie-Aline Martin-Drumel ◽  
Manuel Goubet ◽  
Thi Tran ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
High Resolution ◽  
Gas Phase ◽  
Intramolecular Hydrogen Bond ◽  
Low Frequency ◽  
Thz Spectroscopy ◽  
Intramolecular Hydrogen

The gas-phase infrared spectra of nitromethane and methyl boron difluoride; fine structure caused by internal rotation

1968 ◽  
Vol 304 (1477) ◽  
pp. 135-155 ◽  
Keyword(s):  
Fine Structure ◽  
Gas Phase ◽  
Internal Rotation ◽  
Infrared Spectra ◽  
Degrees Of Freedom ◽  
Coupling Constants ◽  
Modes Of Vibration ◽  
Simplifying Assumptions ◽  
Boron Difluoride ◽  
Vibration Rotation

The gas-phase infrared spectra of nitromethane and methyl boron difluoride have been analysed in some detail. The various skeletal modes of vibration, and the vibrations of the methyl group with dipole changes parallel to the carbon–nitrogen and carbon–boron axes respectively, have vibration–rotation band contours which are of the expected type as calculated from the moments of inertia for overall rotation of the molecules. The perpendicular vibrations of the methyl groups all have complex contours, and in a number of cases widely-spaced fine structure lines are present. These can only be accounted for in terms of the internal rotation degrees of freedom. This is as expected because in classical terms the internal rotation frequencies modulate the oscillating vibrational dipole moment of these (and only these) methyl vibrations; in quantum-mechanical terms this leads to addi­tional transitions involving changes in the quantum number for internal rotation. These perpendicular methyl vibration bands have complex rotational structure because of interaction of the internal rotation degree of freedom with the overall rotations of these asymmetric top molecules. Nevertheless their main Q -branch features have been rather successfully analysed in terms of a theoretical model in which it is assumed that the internal rotation is free, and that the degeneracies of these perpendicular modes are retained. The former is expected to be a good approximation because of the known very low barriers to internal rotation. Some unresolved complexities, particularly towards the centres of the bands, may be caused by deviations from these simplifying assumptions. Analyses of the bands in this manner leads to information about the band origins and to reasonable values for the Coriolis coupling constants of the degenerate vibrations.

Analysis of the Structures and Thermal Properties of Hexanediamine Adipate and Pentanediamine Adipate

2018 ◽  
Vol 876 ◽  
pp. 76-83
Author(s):  
Xiao Wan Yang ◽  
Xin Min Hao ◽  
Jian Ming Wang ◽  
Yan Bin Liu ◽  
Hong Liang Kang
Keyword(s):  
Thermal Properties ◽  
Melting Point ◽  
Infrared Spectra ◽  
Adipic Acid ◽  
Decomposition Temperature ◽  
Bending Vibration ◽  
Out Of Plane ◽  
Stretching Vibration ◽  
Acid Reaction ◽  
The Difference

Hexanediamine adipate, pentanediamine adipate and bio-based pentanediamine adipate were prepared by adipic acid reaction with 1,6-hexanediamine, 1,5-pentanediamine and bio-based 1,5-pentanediamine, respectively. Their structures and thermal properties have been analyzed by infrared spectra, SEM, DSC and TGA. Infrared spectra showed the main differences between 1,6-hexanediamine and 1,5-pentanediamine for the deformation vibration and out of plane bending vibration of N−H. Hexanediamine adipate and pentanediamine adipate had the difference at the asymmetric stretching vibration of −COO-−. The crystal morphologies of hexanediamine adipate and pentanediamine adipate showed dendritic and acicular, respectively. The melting point of pentanediamine adipate, pentanediamine adipate and bio-based pentanediamine adipate were 208.0 °C, 182.3 °C and 182.9 °C, respectively. The polymerization of hexanediamine adipate, pentanediamine adipate and bio-based pentanediamine adipate happened at 201.0, 190.2 and 194.9 °C, respectively. And the decomposition temperature of PA66, PA56 and bio-based PA56 were 401.8, 403.5 and 405.2 °C, respectively.

Infrared spectra and the molecular conformations of some aliphatic amines

1970 ◽  
Vol 48 (20) ◽  
pp. 3229-3235 ◽  
Author(s):  
P. J. Krueger ◽  
J. Jan
Keyword(s):  
Infrared Spectra ◽  
Low Frequency ◽  
Lone Pair ◽  
Frequency Component ◽  
Rotational Isomerism ◽  
Kcal Mole ◽  
Stable Conformer ◽  
Molecular Conformations ◽  
Stretching Vibration ◽  
Bond Trans

The presence of two CD stretching bands for (CH3)2CDNH2 in dilute CCl4 solution is interpreted in terms of two conformations differing in enthalpy by 0.12 ± 0.02 kcal/mole. The low frequency component is assigned to the thermodynamically more stable conformer with the CD bond trans to the N lone pair. Similar rotational isomerism is observed in CH3CD2NH2 and CD3CH2NH2. Band contours for the NH stretching vibration in some N-alkyl anilines reported previously are also interpreted in terms of rotational isomerism and a change in hybridization of the N atom when the lone pair is trans to an α-CH bond, which results in an increase in vNH and a decrease in vCH.

scholarly journals ИК спектроскопия высокого разрешения в низкотемпературных матрицах. Структура фундаментальных полос поглощения SiH-=SUB=-4-=/SUB=- в азотной и аргоновой матрицах

2020 ◽  
Vol 128 (10) ◽  
pp. 1478
Author(s):  
Р.Е. Асфин ◽  
М.В. Бутурлимова ◽  
Т.Д. Коломийцова ◽  
И.К. Тохадзе ◽  
К.Г. Тохадзе ◽  
...  
Keyword(s):  
High Resolution ◽  
Low Temperature ◽  
Gas Phase ◽  
Experimental Conditions ◽  
Bending Vibration ◽  
Argon Matrix ◽  
Solid Nitrogen ◽  
The Matrix ◽  
Stretching Vibration ◽  
Narrow Bands

The features of high resolution IR spectra of the SiH4 molecule in N2 and Ar low-temperature matrices at 6.6-20 K were analyzed depending on experimental conditions. It was found, that in the nitrogen matrix in region of stretching vibration of 28SiH4 three narrow bands are observed, in the region of bending vibration (ν4) two bands are observed instead of one, which is explained by a change in the symmetry of the molecule from Td in the gas phase to C3v in solid nitrogen. In the argon matrix spectra change even more, where, in addition to narrow bands, the broad enough components are also recorded. The calculations of the SiH4 spectrum in the Ar matrix were performed based on the QM/MM approach, which confirm the reality of the change in the symmetry of the molecule as a result of its interaction with the matrix environment.

Hydrogen bonding in the vapour phase between water and hydrogen fluoride: the infrared spectrum of the 1:1 complex

1975 ◽  
Vol 344 (1639) ◽  
pp. 579-592 ◽  
Keyword(s):  
Hydrogen Bond ◽  
Infrared Spectrum ◽  
Hydrogen Fluoride ◽  
Vapour Phase ◽  
Interaction Force ◽  
Bending Vibrations ◽  
Bending Vibration ◽  
A Value ◽  
Stretching Vibration ◽  
First Time

The infrared spectrum of the 1:1 complex in the vapour phase between water and hydrogen fluoride has been observed for the first time, and measured over the range 4000-400 cm -1 . Three bands of the complex have been observed, one associated with the stretching vibration of HF, one with the bending of the water molecule, and the other with two bending vibrations of the hydrogen bond itself. The first band shows that HF forms the hydrogen bond. Interpretation of its fine structure gives the frequencies of two bending vibrations at 145 and 170 cm -1 . The structure of the band associated with the two bending vibrations at about 700 cm -1 has been tentatively analysed to show th at the complex is planar (C 2v ) and to give a value of the Coriolis constant for the interaction of the two vibrations. The value of this constant shows th at either the bending force field has an unusually large interaction force constant or one of the vibrations is anharmonic. W ith the help of an estimated value of the only remaining unknown vibration frequency of the complex, that of the intermolecular stretching vibration at 180 cm -1 , the bending vibration frequencies above, and an estimate of the extinction coefficient of the band associated with the HF stretch, the enthalpy of the association of water and hydrogen fluoride is calculated to be — 26 kJ mol -1 at just above room temperature. From this a value of the potential energy well depth for the interaction has been found to be — 30 kJ mol -1 .

The Infrared Spectrum of the Hydrogen-Bonded Molecule Dimethyl Ether … Hydrogen Chloride in the Gas Phase

1973 ◽  
Vol 51 (11) ◽  
pp. 1713-1720 ◽  
Author(s):  
John E. Bertie ◽  
M. Victor Falk
Keyword(s):  
Hydrogen Bond ◽  
Infrared Spectrum ◽  
Temperature Dependence ◽  
Gas Phase ◽  
Hydrogen Chloride ◽  
Infrared Spectra ◽  
Deformation Band ◽  
Molecular Geometry ◽  
Bond Stretching ◽  
Deformation Modes

A detailed study of the infrared spectra of (CH3)2O … HCl and its isotopic modifications is presented. The hydrogen-bond stretching mode occurs at 119 ± 4 cm−1 in (CH3)2O … HCl, (CD3)2O … HCl, and (CH3)2O … DCl. The O … H—Cl deformation modes yield a band centered at 470 cm−1, which is broad and complex. It is interpreted in terms of sum and difference transitions involving the HCl rocking modes, which are deduced to be at about 50 cm−1. The O … D—Cl deformation band is centered at 360 cm−1. A band at 790 cm−1 in (CH3)2O … HCl and 600 cm−1 in (CH3)2O … DCl is assigned to the overtone of the deformation modes. The shapes of the bands due to the ethereal modes in the molecule can not indicate the molecular geometry and do not agree with the shapes calculated from reasonable moments of inertia. The temperature dependence of the band due to the HCl stretching mode indicates that the fundamental transition is at 2480 cm−1, not at 2574 cm−1 as previously postulated. The DCl stretching band in (CH3)2O … DCl has a different shape to that in (CD3)2O … DCl. The differences are attributed to combination transitions involving the ethereal modes. It is suggested that the DCl and HCl stretching modes interact with the DCl or HCl rocking modes, thus causing shoulders 50 cm−1 away from the DCl stretching fundamental, and contributing to the general diffuseness of the HCl stretching band. The relative intensities of the bands due to (CH3)2O … HCl are presented.

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