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.

The Infrared Spectrum of Ethylene Oxide Clathrate Hydrate at 100°K between 4000 and 360 cm−1

1973 ◽  
Vol 51 (8) ◽  
pp. 1159-1168 ◽  
Author(s):  
John E. Bertie ◽  
David. A. Othen
Keyword(s):  
Hydrogen Bond ◽  
Infrared Spectrum ◽  
Ethylene Oxide ◽  
Infrared Spectra ◽  
Water Molecules ◽  
Weighted Mean ◽  
Bond Lengths ◽  
Line Absorption ◽  
Deformation Modes ◽  
Ring Breathing Mode

The infrared spectra of characterized samples of ethylene oxide hydrate made from 100% H2O, 99.7% D2O, and several dilute isotopic solutions, are presented between 4000 and 360 cm−1. The similarity between the absorption by the water molecules in the hydrate and in ice I is discussed. The frequency and halfwidth of the OH and OD stretching modes of isolated HDO molecules in the hydrate are related to those in the disordered ice phases; the frequencies correlate rather well with the weighted-mean hydrogen bond lengths in these phases.The ethylene oxide vibrations show sharp, single-line absorption. The only exceptions are the ring-breathing mode which appears as a doublet, separated by 2 cm−1, with much weaker absorption about 13 cm−1 away on either side, and the ring deformation modes which interact with the vR(H2O) modes. The possible causes of this behavior are discussed, but no firm conclusions can be drawn. The sharpness of the absorption by enclathrated ethylene oxide, compared to that by liquid ethylene oxide, is briefly discussed in the light of modern theories of bandshapes in liquids.

The infrared spectra of theobromine salts

1967 ◽  
Vol 45 (23) ◽  
pp. 2899-2902 ◽  
Author(s):  
Denys Cook ◽  
Zephyr R. Regnier
Keyword(s):  
Hydrogen Bond ◽  
Nitrogen Atom ◽  
Infrared Spectra ◽  
Imidazole Ring ◽  
Free Base ◽  
Absorption Bands ◽  
Out Of Plane ◽  
Stretching Vibrations ◽  
Deformation Modes ◽  
Infrared Absorption Bands

From the infrared spectra of theobromine salts it is concluded that the salts are probably arranged in hydrogen-bonded centrosymmetric pairs involving [Formula: see text] interactions. [Formula: see text] anion− hydrogen bonds are formed by protonation of the free nitrogen atom (N9) in the imidazole ring. Infrared absorption bands arising from the former hydrogen bond constantly appear near 3 000 cm−1, whereas those from the latter shift from 2 580 to 3 300 cm−1, depending on the anion. In-plane NH and N+H deformation modes give bands near 1 485 and 1 160 cm−1, respectively. Out-of-plane NH modes have been located, but precise assignments are not possible.The assignments for some other bands which show deuteration shifts are detailed, and the carbonyl stretching vibrations which increase in frequency on protonation of the free base are identified.

Infrared and Raman Spectra of Spiropentane-H8

1972 ◽  
Vol 26 (5) ◽  
pp. 540-542 ◽  
Author(s):  
G. R. Burns ◽  
D. G. McGavin
Keyword(s):  
Low Temperature ◽  
Infrared Spectrum ◽  
Gas Phase ◽  
Raman Spectra ◽  
Infrared Spectra ◽  
Sufficient Information ◽  
Infrared And Raman Spectra ◽  
Calorimetric Data ◽  
Crystalline Films ◽  
Twist Mode

Infrared and Raman spectra have been measured for spiropentane-H8. Raman spectra for the liquid have enabled the b1 species ring twist to be assigned. Previous assignments of this mode were based on calorimetric data and on the assignment of a band in the infrared spectrum to a combination band involving the ring twist mode. Infrared spectra of low temperature crystalline films have provided sufficient information that, when taken with the Raman data and gas phase infrared spectra, we have assignments for all of the fundamental modes.

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.

scholarly journals Preparation and the Microwave and Infrared Spectra of Vinyl Ketene

1979 ◽  
Vol 34 (11) ◽  
pp. 1269-1274 ◽  
Author(s):  
Erik Bjarnov
Keyword(s):  
Dipole Moment ◽  
Gas Phase ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Normal Modes ◽  
Spectroscopic Constants ◽  
Electrical Dipole ◽  
Electrical Dipole Moment ◽  
Vacuum Pyrolysis ◽  
Modes Of Vibration

Vinyl ketene (1,3-butadiene-1-one) has been synthesized by vacuum pyrolysis of 3-butenoic 2-butenoic anhydride. The microwave and infrared spectra of vinyl ketene in the gas phase at room temperature have been studied. The trans-rotamer has been identified, and the spectroscopic constants were found to be Ã= 39571(48) MHz, B̃ = 2392.9252(28) MHz, C̃ = 2256.0089(28) MHz, ⊿j = 0.414(31) kHz, and ⊿JK = - 34.694(92) kHz. The electrical dipole moment was found to be 0.987(23) D with μa = 0.865(14) D and μb = 0.475(41) D. A tentative assignment has been made for 17 of the 21 normal modes of vibration

scholarly journals Exploration of Free Energy Surface and Thermal Effects on Relative Population and Infrared Spectrum of the Be6B11− Fluxional Cluster

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 112
Author(s):  
Carlos Emiliano Buelna-Garcia ◽  
José Luis Cabellos ◽  
Jesus Manuel Quiroz-Castillo ◽  
Gerardo Martinez-Guajardo ◽  
Cesar Castillo-Quevedo ◽  
...  
Keyword(s):  
Free Energy ◽  
Infrared Spectrum ◽  
Infrared Spectra ◽  
Thermal Effects ◽  
Global Minimum ◽  
Energy Surface ◽  
Weighted Sums ◽  
Free Energy Surface ◽  
Temperature Dependent ◽  
Relative Population

The starting point to understanding cluster properties is the putative global minimum and all the nearby local energy minima; however, locating them is computationally expensive and difficult. The relative populations and spectroscopic properties that are a function of temperature can be approximately computed by employing statistical thermodynamics. Here, we investigate entropy-driven isomers distribution on Be6B11− clusters and the effect of temperature on their infrared spectroscopy and relative populations. We identify the vibration modes possessed by the cluster that significantly contribute to the zero-point energy. A couple of steps are considered for computing the temperature-dependent relative population: First, using a genetic algorithm coupled to density functional theory, we performed an extensive and systematic exploration of the potential/free energy surface of Be6B11− clusters to locate the putative global minimum and elucidate the low-energy structures. Second, the relative populations’ temperature effects are determined by considering the thermodynamic properties and Boltzmann factors. The temperature-dependent relative populations show that the entropies and temperature are essential for determining the global minimum. We compute the temperature-dependent total infrared spectra employing the Boltzmann factor weighted sums of each isomer’s infrared spectrum and find that at finite temperature, the total infrared spectrum is composed of an admixture of infrared spectra that corresponds to the spectra of the lowest-energy structure and its isomers located at higher energies. The methodology and results describe the thermal effects in the relative population and the infrared spectra.

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