Edward A. Piotrowski

Substituted methanes: Part XXXIV. Raman and infrared spectral data and calculated thermodynamic properties for CH2Cl2, CHDCl2, and CD2Cl2☆☆☆

Raman displacements, semiquantitative relative intensities, and approximate depolarization ratios were obtained for liquid CH2Cl2, CHDCl2, and CD2Cl2; and wave numbers and estimated relative intensities for the infrared bands from 400 to 4000 cycles/cm were obtained for both the liquid and the gas. Vibrational assignments for the deuteriated compounds were made by comparison with the results for CH2Cl2, and by application of the complete isotopic substitution rules of Brodersen and Langseth. The results confirm the infrared work of Shimanouchi and Suzuki for these compounds, except for the σ2 fundamental of CD2Cl2 which was assigned to the 1052 cycles/cm Raman line. Thermodynamic properties (heat content function, free energy function, entropy, and heat capacity) were calculated for twelve temperatures from 100 to 1000°K to a rigid-rotor, harmonic-oscillator approximation.

Raman and Infrared Spectral Data for CH2Br2, CHDBr2, and CD2Br2

Raman displacements, relative intensities, and depolarization ratios have been observed for CH2Br2, CD2Br2, and CHDBr2 in the liquid phase, and the wavenumbers and relative intensities for the infrared bands from 400–4000 cm−1 have been obtained for both the liquid and vapor phases. All but five of the 90 bands observed for the liquid phases of these methanes have been assigned to fundamentals, first overtones, and binary combinations. The assignments for the fundamentals of CH2Br2 are in agreement with previous assignments of Plyler, Smith, and Acquista, but the assignment for the b1 fundamental of CD2Br2 at 2313 cm−1 differs from that of Dowling. The assignments for CD2Br2 were made by comparison with those for CH2Br2, and those for CHDBr2 were made with the aid of the Brodersen and Langseth complete isotopic rule. The present assignments are in better agreement with that rule than are the previous assignments.

Substituted ethanes: Part V. Raman and infrared spectra, assignments, potential constants, and calculated thermodynamic properties for C2F6, C2Cl6, and C2Br6☆☆☆

Abstract Raman displacements, semiquantitative relative intensities, and quantitative depolarization factors as well as the wave numbers and estimated relative intensities for the infrared bands in the region 200 to 3000 cycles/cm were obtained for C2Cl6 in a carbon tetrachloride solution and for C2Br6 in 1,4-dioxane and carbon disulfide solutions. Vibrational assignments consistent with the depolarization data, infrared spectra, and selection rules were made for C2F6, C2Cl6, and C2Br6. Reasonable sets of potential energy constants were determined for the three molecules by use of the Wilson FG matrix method and the procedure of Gold et al. Finally, the thermodynamic properties—heat content, free energy, entropy, and heat capacity—were calculated from the spectral and structural data for 12 temperatures from 100 to 1000°K. In these calculations the contribution of the torsional frequency was included for C2F6 and C2Cl6 but not for C2Br6 since the potential barrier hindering the internal rotation of this molecule was not known.

Substituted Methanes. XXIX. Vibrational Spectra, Potential Constants, and Calculated Thermodynamic Properties for Dibromochlorofluoromethane and Bromodichlorofluoromethane

Raman displacements, semiquantitative relative intensities, and quantitative depolarization factors for the Raman lines of the liquid, and wave numbers and estimated relative intensities for the infrared bands of the gas and liquid in the region 400 to 3000 c/cm (cycles/cm), were obtained for CBr2ClF and CBrCl2F. Assignments of the observed bands were made and reasonable sets of potential energy constants were determined by use of the Wilson FG matrix method and the procedure of Gold, Dowling, and Meister. Finally, the thermodynamic properties—heat content, free energy, entropy, and heat capacity—were calculated from the spectral and structural data for 12 temperatures from 100 to 1000°K.

A force field for difluoramine

From the infra-red spectral data for gaseous difluoramine (NHF2), and difluoroamine-d (NDF2), a set of quadratic valence potential energy constants has been obtained. The constants for the N-H and N-F stretchings are respectively 5·6474 and 4·0681 mdyn/A. These values are somewhat less than the corresponding values for NH3 and NF3 and are consistent with slightly longer N-H and N-F distances in difluoroamine.

Substituted methanes: Part XXXVII. Raman and infrared spectral data, and calculated wave numbers for CD2BrCl and CHDBrCl

Abstract The Raman spectra for the liquid, and the infrared spectra for both the gas and liquid have been obtained for CD 2 BrCl and a mixture of CH 2 BrCl, CD 2 BrCl, and CHDBrCl. The vibrational spectral data for CHDBrCl were deduced by eliminating the known bands of CH 2 BrCl and CD 2 BrCl from the data for the mixture. The assignments for CD 2 BrCl and CHDBrCl were confirmed by potential energy constant calculations. The observed values for the fundamentals of CD 2 BrCl in the Raman spectrum are: a ′—226, 574, 702, 922, 1042, and 2196; a ″—667, 809, and 2305. In the infrared, the values are: liquid—574, 703, 923, 1041, 2195, 668, 2302; gas—582, 717, 936, 1050, 2208, 811. The calculated wave numbers are: a ′—227, 564, 693, 926, 1055, 2161; a ″—672, 810, and 2250. For CHDBrCl, in the Raman spectrum the observed values for the fundamentals are: 228, 586, 707, 743, 867, 1179, 1264, 2246, and 3024; and in the infrared they are: gas—711, 746, 868, 1188; liquid—706, 743, 865, 1183, 1262, 2252, 3031. The calculated wave numbers are: 227, 578, 704, 740, 878, 1155, 1283, 2205, and 3020.

The Vibrational Spectra of trans-C2H2I2 and trans-C2D2I2

With the availability of the deuterated form of trans-C2H2I2, it was decided to examine the vibrational spectrum of trans- C2D2I2 and thereby obtain a more complete assignment of the vibrational frequencies of the trans-diiodoethylenes. The only previous spectral work done on the cis- andtrans-diiodoethylenes was by Miller et al. [1], Since their Raman spectrum was obtained with a low resolution spectrograph, the Raman and infrared spectra of the trans-C2H2I2 were also reinvestigated.

The Vibrational Spectrum and Structure of Symmetric Tetrabromoethane and Its Deuterate Analogs

Raman and infrared spectral studies have indicated the existence of rotational isomerism for substituted ethanes. Tetrabromoethane (CBr2H-CBr2H) is considered to exist in the trans and gauche forms. Therefore, the analysis of the Raman and infrared spectra entails the assignment of the vibrational frequencies to one or the other form. A partial assignment of this type has been made by Kagarise [1] for C2H2Br4. A more complete assignment could be made if knowledge of the vibrational frequencies of C2D2Br4 were available. In the present investigation the Raman and infrared spectra of C2H2Br4 and C2D2Br4 have been obtained. As the Raman and infrared spectra of C2H2Br4 obtained in this investigation are essentially the same as those reported by Kagarise [1], they will not be given here. As for C2D2Br4 the Raman displacements in cycles per centimeter, relative intensities, and depolarization factors (Δσ(1)ρ) are: 63(15)0.73; 112(13)0.55; 146(17)0.70; 175(19)0.68; 217(100)0.11; 434(7)0.77; 520(20)0.03; 603(6)0.35; 659(25)0.43; 793(2)0.82; 835(1)0.86; 873(3)0.72; 900(16)0.65 944(0)0.66?; 973(1)0.86; 1065(12)0.21; and 2228(12)0.34. The wave numbers in cycles per centimeter for the more prominent bands in the infrared spectrum of C2D2Br4 are: 430(s); 520(s); 569(m); 592(vs); 611(m); 656(vs); 833(vs); 900(vs); 976(vs); 1069(s); and 2232(vs). The Raman and infrared data for C2H2Br4 and C2D2Br4 have been compared to arrive at a complete assignment of the observed bands. As a check on the assignments, a normal coordinate treatment using the Wilson FG matrix technique has been carried out for the frans isomer of each molecule.