Conformational Analysis of 2, 3, 3-Trimethylhexane

Infrared and Raman spectra were obtained for 2, 3, 3-trimethylhexane and were interpreted with the aid of normal coordinate calculations. It was concluded that this compound exists in three molecular conformations, but a fourth conformer may exist. Vibrational assignments were made for the three conformers.     

Conformational Analysis of 4,4-Dimethylheptane

Abstract

Infrared and Raman spectra were obtained for 4,4-dimethylheptane and were interpreted with the aid of normal coordinate calculations. It was shown that this compound exists in three conformations. Force constant values transferred from dimethylpentanes resulted in an overall average difference between observed and calculated wavenumbers of 4.5 cm^?1 for the three conformers.     

Vibrational Analysis of 1,2-Dibromopropane and 1,2-Dibromopropane-D6

Abstract

Infrared spectra were obtained for 1,2-dibromopropane-d₆ in the liquid and in the unannealed and annealed solid states. Vibrational assignments were made for the three conformers of 1,2-dibromopropane and the three conformers of 1,2-dibromopropane-d₆ with the aid of normal coordinate calculations. All three possible conformers of CD₂BrCDBrCD₃ were found to be present in the liquid and unannealed solid, but the P_HS_HH conformer was absent in the annealed solid.     

Conformational Analysis of 1,2-Dichlorobutane

Vibrational spectra have been published and normal coordinate calculations have been made for 1,2-dichlorobutane.^1,2 Those calculations were limited to the three conformers that had all four carbon atoms coplanar. Molecular mechanics calculations have now shown a conformer that was omitted to be the second most abundant conformer. Therefore, normal coordinate calculations have been made for this conformer and molecular mechanics calculations have been made for all possible conformers.     

Conformational Analysis of 3,3-Dimethylhexane

Abstract

Infrared and Raman spectra were obtained for 3,3-dimethylhexane and were interpreted with the aid of normal coordinate calculations. It was shown that this compound exists in more than one molecular conformation. Two of those conformations were identified. Transferred force constant values resulted in an overall average difference between observed and calculated wavenumbers of 4.6 cm^?1 for the two conformers.     

Conformational Analysis of 3,3,4-Trimethylhexane and 2,2,5-Trimethylhexane

Infrared and Raman spectra were obtained for 3,3,4-trimethylhexane and 2,2,5-trimethylhexane and were interpreted with the aid of normal coordinate calculations. It was shown that each compound exists as a mixture of two molecular conformations.     

Vibrational and Conformational Analysis of 5-Methyl-2-Hexyne

Infrared and Raman spectra were obtained for 5- methyl-2-hexyne and wereinterpreted with the aid of normal coordinate calculations. The spectra and molecular mechanics calculations show the compound to exist in two spectroscopically distinguishable stable conformations, with the C₁ conformer being only a little more stable than the C_s, conformer. Vibrational assignments were made for both conformers.     

Conforhational Analysis of 3,3-Dimethylheptane

Infrared and Raman spectra were obtained for 3,3-dimethylheptane and were interpreted with the aid of normal coordinate calculations. The presence of only three conformers could be verified in this way. Molecular mechanics calculations showed the probable presence of all eleven possible conformers, with concentrations ranging from 27% to 33%. Structural parameters and the heat of formation were obtained from the calculations.     

An Infrared Study of Conformational Isomerism in Cyclohexyl Iodide

Abstract

A comprehensive solvent, concentration, and temperature study has been made of the 850 to 400 cm^?1 region of the infrared spectrum of cyclohexyl iodide. This causes us to reject the assignment of Larnaudie and of Chiurdoglu and Reisse of v(C-I)_eq at 654 cm^?1 and v(C-I)^ax at 638 cm^?1, and to suggest that the two modes are almost coincident in n-hexane solution at 656.2 cm^?1 (eq) and 655.6 cm^?1 (ax).     

Conformational Analysis of Some Dichloroalkanes

Molecular mechanics calculations were made for 1,1-dichlorobutane, 2,2-dichlorobutane, and 1,2-dichloro-2-methylpropane in order to compare the results with conclusions obtained from vibrational spectra concerning the conformational behavior of these compounds. Calculations were also made for 1,2-dichloro-2-methylbutane, although vibrational spectra are not available for this compound. The structures and relative energies of the most abundant conformers are given.     

Vibrational and Conformational Analysis of 2-Methyl-1-butene

Normal coordinate calculations were made for 2-methyl-1-butene to aid in making vibrational assignments for both conformers. A partial solid-state IR spectrum was obtained that showed the presence of only the trans (C_s) conformer. Molecular mechanics and semi-empirical molecular orbital calculations were also made for both conformers.     

Normal Coordinate Analysis of 3-Bromo-1,3-Dinitroazetidine

Abstract

The infrared spectrum of 3-bromo-1,3-dinitroazetidine was interpreted with the aid of normal coordinate calculations. A seventy-two parameter modified valence field was used in those calculations, and the observed wave numbers were fit with an average error of 2.5 cm^?1. An assignment of the bands in terms of symmetry coordinates is given. Many of the force constants were transferred to 1-acetyl-3,3-dinitroazetidine to aid in normal coordinate calculations for that compound.     

Vibrational Spectra,Normal Coordinate Calculations,and Molecular Mechanics Calculations for 2, 3, 3-Trimethyl-1-Butene

Infrared and Raman spectra were obtained for 2, 3, 3-trimethyl-1-butene, and a vibrational assignment was made with the aid of normal coordinate calculations. Molecular mechanics calculations were also made to determine molecular parameters of the stable conformation. Values for the force constants of a forty-one parameter modified valence force field were obtained that will be used for other 2-methyl-1-alkenes that contain substituted methyl groups.     

Molecular constants of XeO3F2

The force constants of XeO₃F₂ have been evaluated using the general valence force field. The mean square amplitudes of vibration, the generalised mean square amplitudes and shrinkage constants, Coriolis coupling coefficients and centrifugal distortion constants have also been calculated for the first time using the vibrational frequencies and the structural parameters. The thermodynamic properties have been computed for the ideal gaseous state at 1 atmospheric pressure for 11 temperatures from 100° to 1000°K using a rigid rotor harmonic oscillator approximation.     

Conformational Analysis of Some Monochloroalkanes

Molecular mechanics calculations were made for 2-chloro-2,3-dimethylbutane, 2-chloro-2,4-dimethylpentane, and 2-chloro-2,5-dimethylhexane in order to compare the results with conclusions obtained from vibrational spectra concerning the conformational behavior of these compounds. The structures, relative energies, and heats of formation were also calculated.     

VIBRATIONAL SPECTRA AND NORMAL COORDINATE ANALYSIS OF 1,2-BIS(2-FORMYLGLYCINEBENZENESULFENYL) ETHANE Pd(II) DICHLORIDE COMPLEX

The normal coordinate analysis of the title complex, 1,2-bis(2-formylglycinebenzenesulfenyl) ethane Pd(II) dichloride has been carried out by using the Urey-Bradley force field. According to the molecular structure determined by x-ray crystallographic analysis, 182 internal coordinates were established and 112 theoretical vibration frequencies agree well with the observed values with the average difference of 2.53 cm^?1 and the maximum deviation of 16.0 cm^?1.     

穴醚［2．2．2］的HgCl_2，CdCl_2及Cd（NO_3）_2配合物的红外

本文合成了穴醚［２．２．２］的ＨｇＣｌ２，ＣｄＣｌ２及Ｃｄ（ＮＯ３）２配合物，用元素分析数据确定了它们的化学组成，并对其红外和拉曼光谱进行了经验归属。基于这两组数据推测了配合物的结构。     

Single- and multi-photon absorption of carbon dioxide laser lines by SO2 and CO2 molecules

Summary We have used 60 rovibrational lines of a Lumonics TEA CO₂ laser to record the spectra of coincidence of SO₂ IR absorption with CO₂ laser emission. We extended the same type of investigation to CO₂ molecules and observed an absorption at practically all the rovibrational lines of the laser. We have also recorded the increase of absorption with pressure of the studied molecule and with its temperature. Our work reveals very accurately the fine structure of these absorptions that shows a clear discreteness in the intensities of the lines. Some implication of this discreteness in multiphoton absorption is also presented, through data that indicate very strong vibrational coupling between ground and excited electronic states of SO₂. The authors of this paper have agreed to not receive the proofs for correction.     

Conformational Analysis of Some Chloro and Bromoalkanes

Rotational isoraerism has been shown by vibrational spectroscopy to exist in l-chloro-3-methylbutane,¹ l-chromo-3-methylbutane,² 2-chloro-4-methylpentane,^3,4 2-bromo-4-methylpentane,⁴ 1,3-dichlorobutane,⁵ and 1,3-dibromobutane.⁵ In some cases, definite conclusions were drawn concerning the number and identification of the conformers present. In other cases, it was not possible to determine with certainty which conformers exist. Molecular mechanics calculations have now been made for these six compounds in order to obtain additional information about their conformational behavior, including energies and structures of the possible conformers. The calculations were done with the MM2 program written by Allinger and Yuh and converted by Petillo to run on a microcomputer.⁶     

Vibrational Analysis of 2,3-Dimethyl-1-Butene

Infrared and Raman spectra were obtained for 2,3-dimethyl-1-butene. The spectra showed the presence of two stable conformations. Vibrational assignments were made for both conformers with the aid of normal coordinate calculations. Values for the force constants that were obtained will be used in the future as the initial values for other substituted 1-alkenes, such as 2-isopropyl-3-methyl-1-butene.