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.

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.

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.

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.

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.

Selenoketone spectroscopy: vibronic analysis of the and n → π electronic transitions in F2CSe

1983 ◽  
Vol 61 (8) ◽  
pp. 1743-1748 ◽  
Author(s):  
M. Y. Bölük ◽  
D. C. Moule ◽  
D. J. Clouthier
Keyword(s):  
Energy Levels ◽  
Vibrational Analysis ◽  
Wavelength Region ◽  
Electronic Transitions ◽  
Vibrational Assignments ◽  
Continuous Structure ◽  
Out Of Plane ◽  
Minimum Potential ◽  
Vibronic Analysis

The spectrum of F2CSe has been surveyed over the 700–200 nm wavelength region and three distinct absorptions identified. These are the spin-allowed, [Formula: see text] and spin-forbidden [Formula: see text] overlapping n → π* transitions, λmax = 434 nm, and the orbitally-allowed [Formula: see text] transition, λmax = 236 nm. Vibrational assignments for the band systems have been made and the out-of-plane energy levels analyzed in terms of a quadratric-Lorentzian double minimum potential. The barriers to inversion for the Ã1A2/ã3A2 states were found to be 2483/2923 cm−1 and the out-of-plane angles 30.1/31.4 deg. The singlet–triplet separation was E(Ã1A2) − E(ã3A2) = 671 cm−1 The [Formula: see text], system displays continuous structure and was not subject to a vibrational analysis.

Two Emission Band Systems of SeO in the Photographic Infrared

1973 ◽  
Vol 51 (20) ◽  
pp. 2166-2174 ◽  
Author(s):  
M. Azam ◽  
S. Paddi Reddy
Keyword(s):  
Emission Band ◽  
Band System ◽  
Vibrational Analysis ◽  
Spin Splitting ◽  
Vibrational Assignments ◽  
Forbidden Transition ◽  
Splitting Constant ◽  
Region 10 ◽  
First Time ◽  
Single Sequence

Two emission band systems of SeO consisting of 46 bands degraded to longer wavelengths have been observed for the first time in the spectral region 10 780–9490 Å. The vibrational analysis of one system which consists of several double-headed bands shows that it arises from the forbidden transition b1Σ+–X3Σ−. The double-headed bands have been analyzed as belonging to the 1Σ+–X3Σ−(F1) and 1Σ+–X3Σ−(F2,F3) subsystems. The separations between the corresponding band heads of these two subsystems are consistent with the expected value of ~ 2λ, λ(= 86.4 cm−1) being the spin splitting constant of the X3Σ− state derived previously from a detailed rotational analysis of the B3Σ−–X3Σ− (denoted earlier as the A3Σ−–X3Σ−) system. The vibrational assignments are confirmed by the observed isotope band heads of 82SeO,80SeO,78SeO, and 76SeO. The second band system, which consists of a single sequence of bands in the region 10 780–10 500 Å, is tentatively assigned to the probable forbidden transition (a1Δ)–(X3Σ−).

Vibrational analysis of alkyl bromides. II. Secondary bromides

1977 ◽  
Vol 55 (19) ◽  
pp. 3413-3419 ◽  
Author(s):  
G. A. Crowder ◽  
Maurice Iwunze
Keyword(s):  
Force Field ◽  
Raman Spectra ◽  
Vibrational Analysis ◽  
Average Error ◽  
Infrared And Raman Spectra ◽  
Normal Coordinate ◽  
Valence Force ◽  
Vibrational Assignments ◽  
Valence Force Field ◽  
Alkyl Bromides

Infrared and Raman spectra were obtained for 2-bromopentane, 3-bromopentane, 2-bromohexane, and 3-bromohexane. Vibrational assignments were made for several conformers of each compound with the aid of normal coordinate calculations. A 48 parameter modified valence force field was obtained that fit 221 frequencies of three conformers of 2-bromopentane, 4 conformers of 3-bromopentane, and 1 conformer of 2-bromobutane with an average error of 4.1 cm−1. This force field was transferred to the bromohexanes, with good results.

Vibrational analysis as a function of the chain-length of well-barrier-well π-conjugated thiophene-based oligomers

1997 ◽  
Vol 84 (1-3) ◽  
pp. 591-592 ◽  
Author(s):  
V. Hernàndez ◽  
A. Berlin ◽  
G. Zotti ◽  
J.T. López Navarrete
Keyword(s):  
Chain Length ◽  
Vibrational Analysis

Vibrational analysis of the 3Π1–X1Σ+ band systems of SiCl+

1981 ◽  
Vol 59 (8) ◽  
pp. 985-989 ◽  
Author(s):  
Masaharu Tsuji ◽  
Toshinori Mizuguchi ◽  
Yukio Nishimura
Keyword(s):  
Emission Spectrum ◽  
Radical Cation ◽  
Thermal Energy ◽  
Vibrational Analysis ◽  
Molecular Constants ◽  
Vibrational Assignments

The emission spectrum of the SiCl+ radical cation, excited by the thermal energy He+ + SiCl4 reaction, has been observed and vibrationally analyzed in the 310–350 nm region. The two new subband systems, [Formula: see text] and a3Π1–X1Σ+, have been identified. The vibrational assignments were confirmed by the observed isotope band heads of Si35Cl+ and Si37Cl+. The following molecular constants (in cm−1) have been obtained for the X1Σ+, [Formula: see text], and a3Π1, states.[Formula: see text]

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