Group vibrations and the vibrational analysis of molecules containing methylene groups. Part II. Ethylene oxide, d4-ethylene oxide, and ethylene sulfide

1968 ◽  
Vol 46 (12) ◽  
pp. 2135-2139 ◽  
Author(s):  
J. M. Freeman ◽  
T. Henshall
Keyword(s):  
Ethylene Oxide ◽  
Vibrational Analysis ◽  
Vibrational Assignments ◽  
Group Frequency ◽  
Methylene Groups

Vibrational analyses, based on the group frequency factorization procedure of King and Crawford, are reported for ethylene oxide, d4-ethylene oxide, and ethylene sulfide in an attempt to decide between two possible vibrational assignments for these molecules.The results, whilst not providing an unequivocal decision between the assignments, nevertheless do suggest that the higher frequencies in the A2 and B2 species may be preferentially assigned to the methylene rocking modes.

Vibrational assignments and force-field calculations for ethylene oxide

1975 ◽  
Vol 31 (7) ◽  
pp. 839-853 ◽  
Author(s):  
N.W. Cant ◽  
W.J. Armstead
Keyword(s):  
Ethylene Oxide ◽  
Force Field ◽  
Force Field Calculations ◽  
Vibrational Assignments

Rotational analysis of the 2600a absorption system of benzene

1966 ◽  
Vol 259 (1104) ◽  
pp. 499-532 ◽  
Keyword(s):  
Excited States ◽  
Point Group ◽  
Vibrational Analysis ◽  
Resolving Power ◽  
Rotational Analysis ◽  
Absorption System ◽  
Vibrational Assignments ◽  
Anharmonic Constants ◽  
Equilibrium Configurations ◽  
Very High

The 2600A absorption system of benzene has been examined with very high resolving power, and the rotational fine structure partially analysed by comparison with computed contours. Vibronic bands involving degenerate e2g vibrations have contours characteristic of the vibrational angular momentum, and Coriolis coefficients £ have been determined for the lowest e2g vibrations in ground and B2u excited states. Band contours thus provide an additional criterion for checking vibrational assignments. In particular, values of £ determine the separation between band maximum and origin which can thus be calculated, and the vibrational analysis consequently refined in certainty and precision. Improved values of several fundamentals have been obtained, some new vibrational assignments made, and some previous ones rejected. Some important anharmonic constants have also been obtained. Vibronic relative intensities are briefly discussed. The rotational and vibrational evidence together make it certain that the equilibrium configurations of the carbon skeleton in benzene are exactly planar and hexagonal in both the ground and excited states, point group Z)6A. The rotational constants then give an estimate of the increase in G—C distance on excitation of + 0*038 A, in excellent agreement with estimates from other sources. The electronic origin of the system is revised: T00 = 38086*1 cm

Conformational and Vibrational Analysis of 2,4-, 2,5- and 2,6-Difluorobenzaldehydes by ab initio Hartree-Fock and Density Functional Theory Calculations

2008 ◽  
Vol 63 (3-4) ◽  
pp. 175-182 ◽  
Author(s):  
Adnan Sağlam ◽  
Fatih Ucun
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Vibrational Analysis ◽  
Molecular Structures ◽  
Basis Set ◽  
Functional Theory ◽  
Vibrational Assignments ◽  
Hartree Fock ◽  
The Mean

The optimized molecular structures, vibrational frequencies and corresponding vibrational assignments of the two planar O-cis and O-trans rotomers of 2,4-, 2,5- and 2,6-difluorobenzaldehyde have been calculated using ab initio Hartree-Fock (HF) and density functional theory (B3LYP) methods with the 6-311++G(d,p) basis set level. The calculations were adapted to the CS symmetries of all the molecules. The O-trans rotomers with lower energy of all the compounds have been found as preferential rotomers in the ground state. The mean vibrational deviations between the vibrational frequency values of the two conformers of all the compounds have been shown to increase while the relative energies increase, and so it has been concluded that the higher the relative energy between the two conformers the bigger is the mean vibrational deviation.

Group vibrations and the vibrational analysis of molecules containing methylene groups. Part I. The basic equations and the application of the method to methylene dichloride and cyclopropane

1968 ◽  
Vol 46 (12) ◽  
pp. 2129-2134 ◽  
Author(s):  
J. M. Freeman ◽  
T. Henshall
Keyword(s):  
Vibrational Analysis ◽  
Ring System ◽  
Form Part ◽  
Methylene Groups ◽  
Basic Equations ◽  
Bending Modes ◽  
Deformation Modes ◽  
Methylene Group ◽  
Molecular Framework ◽  
Secular Determinant

The vibrations of the methylene group first considered by King have been reexamined; and the group factorization procedure previously applied to molecules containing methyl groups has now been extended to molecules containing methylene groups. The vibrational analysis of such molecules can be simplified by factoring from the secular determinant those frequencies that are characteristic of the symmetric and antisymmetric CH2 stretching, and the [Formula: see text] angle bending modes. Corrections are then applied to the G and F matrices to account for the interactions with the molecular framework of the CH2 'rocking', and [Formula: see text] angle deformation modes, where the atoms X may form part of a ring system.

scholarly journals Solid-state linear polarized IR-spectroscopy of croconic and rhodizonic acids

2008 ◽  
Vol 6 (3) ◽  
pp. 393-399 ◽  
Author(s):  
Tsonko Kolev ◽  
Bojidarka Koleva ◽  
Michael Spiteller
Keyword(s):  
Solid State ◽  
Ir Spectroscopy ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Vibrational Analysis ◽  
Basis Set ◽  
Experimental Ir ◽  
Vibrational Assignments ◽  
Neutral Compounds ◽  
Polarized Ir Spectroscopy

AbstractThe applications of linear-polarized IR-spectroscopy to oriented colloid suspensions in a nematic host are demonstrated with croconic and rhodizonic acids. The experimental IR vibrational assignments of the solid-state of both neutral compounds are presented. Assignments are supported by theoretical quantum chemical calculations and vibrational analysis at the DFT level of theoretical approximation with the 6-311++G** basis set.

Vibrational analysis of (E,E)-2,4-hexadienal, (E,E,E)-2,4,6-octatrienal, and (E,E,E)-3-methyl-2,4,6-octatrienal

1985 ◽  
Vol 63 (7) ◽  
pp. 1587-1593 ◽  
Author(s):  
M. M. Abo Aly ◽  
M. H. Baron ◽  
J. Favrot ◽  
J. Belloc ◽  
M. Revault
Keyword(s):  
Chain Length ◽  
Vibrational Analysis ◽  
Vibrational Assignments ◽  
Aldehydic Group

Attempted vibrational assignments of (E,E)-2,4-hexadienal, (E,E,E)-2,4,6-octatrienal, and (E,E,E)-3-methyl-2,4,6-octatrienal are given between 3100 and 50 cm−1. We particularly discuss spectroscopic effects of the aldehydic group presence, enlargement of the polyenal chain length, and methyl lateral substitution.

A Comparative Study of Ionic Association in Poly(Ethylene Oxide)- MCF3SO3 Systems (M=Lithium and Sodium)

1998 ◽  
Vol 548 ◽  
Author(s):  
Roger Frech ◽  
Christopher P. Rhodes ◽  
Shawna S. York
Keyword(s):  
Ethylene Oxide ◽  
Vibrational Analysis ◽  
Ionic Association ◽  
Infrared Spectroscopic Study ◽  
Lithium Triflate ◽  
Compound Formation ◽  
Anionic Species ◽  
Energy Environment ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

ABSTRACTA comparative infrared spectroscopic study of the local vibrational potential energy environment of the CF3SO3 (triflate) anion in the poly(ethylene oxide)-lithium triflate and poly(ethylene oxide)-sodium triflate systems is presented. Analysis of the crystalline stoichiometric compounds in the two systems identifies significant differences in the ionic association. Comparison of the relative percentages of the anionic species in the PEO-NaTf system at various concentrations suggests that crystalline compound formation may proceed through intermediate structures. A symmetry-based vibrational analysis is applied to the crystalline compounds.

scholarly journals Synthesis, Molecular Structure, HOMO-LUMO, Chemical, Spectroscopic (UV-Vis and IR), Thermochemical Study of Ethyl 6-amino-5-cyano-2-methyl-4-(4-nitrophenyl)-4H-pyran-3-carboxylate: A DFT Exploration

2021 ◽  
Vol 18 (2) ◽  
pp. 179-189
Author(s):  
Vishnu A. Adole ◽  
Tejendra R. Rajput ◽  
Bapu S. Jagdale
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Vibrational Analysis ◽  
Basis Set ◽  
Thermochemical Study ◽  
Contour Plot ◽  
Dft Methods ◽  
Functional Theory ◽  
Vibrational Assignments ◽  
Td Dft

The ethyl 6-amino-5-cyano-2-methyl-4-(4-nitrophenyl)-4H-pyran-3-carboxylate (ACNPPC) was synthesized using an environmentally friendly method and looked into in terms ofstructural, UV-visible, vibrational, and computational analysis. In the gaseous phase, calculations of the density functional theory (DFT) with B3LYP/6-311G(d,p) level were performed. Using Time-dependent density functional theory (TD-DFT) with the B3LYP/6-311G(d,p) basis set method, the HOMO and LUMO energies are calculated. For assessing electrophilic and nucleophilic reactive sites, the molecular electrostatic surface potential (MESP) and contour plot were plotted over the optimized structure. Using computed and experimental vibrational spectra, vibrational assignments were elucidated. To illustrate the charge density in the title compound, Mulliken atomic charges are disclosed. In addition, using vibrational analysis, some thermochemical functions have also been derived. Theoretical simulations have shown the best relationship with experimental results obtained with the B3LYP/6-311G(d,p) level of theory at the DFT and TD-DFT methods.

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