J.C. Evans

The vibrational assignments and configuration of aniline, aniline-NHD and aniline-ND2

Abstract The Raman spectra (liquid phase) and infrared spectra (vapor, solution and liquid phases) of aniline, aniline-NHD and aniline-ND2 were studied, the infrared study being in the 320–3800 cm−1 range for the liquids and solutions and in the 400–3800 cm−1 range for the vapors. A complete vibrational assignment for aniline and almost complete assignments for the other two molecules were made. The data are interpreted on the basis of a non-planar configuration for these molecules. The barrier hindering internal rotation about the C-N bond is calculated to be 3.54 kcal mole while the barrier to inversion at the nitrogen atom is estimated to be at least 4.5 kcal mole . The entropy calculated for aniline vapor is in good agreement with the measured value.

The vibrational spectra of phenol and phenol-OD

Raman spectra (liquid phase) with depolarization measurements and infrared spectra (vapor, solution, liquid and solid phases) in the 300–3800 cm−1 region are reported for phenol and phenol-OD. A complete vibrational assignment for phenol is presented and a value of 3·37 kcal/mole has been determined for the barrier to internal rotation about the C—O bond. Thermodynamic functions for phenol as an ideal vapor at 1 atm pressure have been calculated.

Further studies of unusual effects in the infrared spectra of certain molecules

Abstract The qualitative explanation previously offered [1] to explain an unusual feature in the infrared absorption spectrum of m -toluidine has been expressed in quantitative terms. Further examples of the effect are described and are compared with theoretical predictions. The simple theory is adequate in many cases and departures from the expected band shapes are ascribed to inadequacies of certain assumptions made in the derivation.

Vibrational spectra and assignments for sixteen chlorobenzenes

Abstract Infrared and Raman spectra have been measured and complete vibrational assignments are given for the following molecules: o -C 6 Cl 2 H 4 , o -C 6 Cl 2 D 4 , m -C 6 Cl 2 H 4 , p -C 6 Cl 2 H 4 , p -C 6 Cl 2 D 4 , 1,2,3-C 6 Cl 3 H 3 , 1,2,3-C 6 Cl 3 D 3 , 1,2,4-C 6 Cl 3 H 3 , 1,2,3,4-C 6 Cl 4 H 2 , 1,2,3,5-C 6 Cl 4 H 2 , 1,2,4,5-C 6 Cl 4 H 2 , 1,2,4,6-C 6 Cl 4 D 2 , 1,2,4,5-C 6 Cl 4 HD, C 6 Cl 5 H, C 6 Cl 5 D, C 6 Cl 6 . A modified Urey-Bradely force field was used to predict the planar vibrational frequencies and our assignment has been guided largely by this zero-order calculation. A valence force-field was used to predict the non-planar frequencies. While this calculation gave poorer agreement with the observed fundamentals than did the planar calculation, it did yield the approximate spectral regions where these fundamentals should occur. Tentative assignments are proposed for all overtones and combination bands which appear in the infrared and Raman spectra.

Narrow transmission regions within broad infrared absorption bands in solids

Abstract Infrared and Raman studies of some selected examples of transmission anomalies sometimes observed within broad infrared absorption bands of solids indicate that perturbations between overlapping energy levels provide a reasonable explanation for these effects.

Acetyl halides—I: Infrared and Raman spectra and vibrational assignment of CH3COCl, CD3COCl and CH2DCOCl

Abstract The infrared and Raman spectra of acetyl chloride, acetyl chloride-d3 and acetyl chloride-d1 have been studied and a vibrational assignment has been made on the basis of an approximate normal-co-ordinate calculation with a Urey-Bradley field. It is proposed that the two intense bands at 1109 and 958 cm−1 in the infrared spectrum of acetyl chloride correspond to vibrational modes which are mixtures of the C-C stretching co-ordinate and the CH3 rocking co-ordinate, and that the similar pair of intense bands in the CD3COCl spectrum arise from modes which are mixtures of CC stretching and CD3 deformation co-ordinates. Thermodynamic functions were calculated for acetyl chloride in the ideal gaseous state.

The vibrational spectra and vibrational assignments of the propargyl halides

Abstract Liquid-phase Raman spectra (100–3400 cm −1 ) and vapor-phase and solution-phase infrared spectra (300–3800 cm −1 ) were obtained for propargyl fluoride, chloride, bromide and iodide. Complete vibrational assignments were made.

Vibrational spectra of sym-trichlorobenzene and the Mair-Hornig assignment of benzene

The vibrational spectra of the deuteroisotopic mixtures of sym-trichlorobenzene have been measured and analyzed and complete assignments of the H3 and D3 molecules and partial assignments of the H2D and D2H molecules were made. It is demonstrated that a basic Urey-Bradley Force Field is inadequate to describe certain of the observed B2-fundamentals of sym-trichlorobenzene-d. In the instances where the basic UBFF fails, the Kekule model proposed by scherer and overend accounts for the discrepancies between observed and calculated frequencies. The success of this model is submitted as evidence for the validity of the mair-hornig assignment of the B2u-fundamentals of benzene. The value of the Kekule constant for sym-trichlorobenzene is found to be 0.400 ± 0.018 mdyn/A compared with 0.351 ± 0.019 mdyn/A for benzene.

A peculiar effect in the infrared spectra of certain molecules

A peculiar effect, which is believed to be of general occurrence although not frequently encountered, has been studied in the infrared spectrum of m-toluidine. Studies of the infrared spectra in various phases at different temperatures, of the infrared spectrum of liquid m-toluidine ND2 and of the Raman spectra of both molecules in the liquid state aided in the interpretation. It is proposed that at any instant in liquid m-toluidine a special perturbation occurs between certain vibrational energy levels in a small fraction of the molecules. In the majority of the molecules this perturbation is very weak or is absent.

Raman and infrared studies of acetonitrile complexed with zinc chloride

Abstract Raman and infrared studies of aqueous zinc chloride solutions containing CH 3 CN or CD 3 CN show that the complexed nitrile retains its original C 3 v symmetry, the point of attachment to the zinc atom being through the nitrogen lone-pair electrons. Normal coordinate calculations using the model, CH 3 CN.Zn, indicate that the CN stretching force constant is increased by complex formation.