Jerome M. Dowling

Calculation of rotational distortion constants for some axially symmetric ZX3Y molecules

Abstract The changes of the moment of inertia with respect to the symmetry coordinates of an axially symmetric ZX3Y molecule are evaluated. With these derivatives and formulas in the literature, explicit equations can be written for the rotational distortion constants DJ, DJK, and DK in terms of the masses, internuclear distances, interbond angles and (F−1)ij the elements of the matrix inverse to the potential energy matrix. Rotational distortion constants are then calculated for CCl35H3, CBr79H3, CHF3, CCl335H, CBr79F3, and CIF3. The agreement with previously reported experimental data is fair, except for CCl335H.

On the “redundant coordinate” problem in the rotational-vibrational spectra of polyatomic molecules

Abstract A consistent method is described for treating redundant coordinates in the Wilson treatment of the rotational-vibrational problem of polyatomic molecules. This method furnishes a unique set of potential constants for molecules having redundant internal coordinates. Techniques are developed which permit the calculation of the rotational distortion constants by use of the internal coordinates. A method is given for obtaining the partial derivatives of the moment of inertia tensor with respect to the internal coordinates which is applicable even when redundant coordinates are present. The results for a ZX 3 Y molecule are tabulated in matrix form.

Vibrational Spectra, Potential Constants, and Calculated Thermodynamic Properties of cis‐ and trans‐BrHC=CHBr, and cis‐ and trans‐BrDC=CDBr

Raman displacements for the liquid and infrared absorption wave numbers for both liquid and gas, together with quantitative depolarization factors for the Raman lines and semiquantitative relative intensities for both Raman and infrared bands, have been obtained for cis‐ and trans‐BrHC=CHBr and cis‐ and trans‐BrDC=CDBr. Assignments, consistent with the selection rules, were made for the 4 molecules. As a further check on the assignments a normal coordinate treatment (Wilson FG matrix method) was carried out. The heat content, free energy, entropy, and heat capacity for each of the molecules were calculated for 12 temperatures from 100 to 1000°K for the ideal gaseous state at 1 atmos pressure. Finally the energy difference between the cis‐ and trans‐isomers of C2H2Br2 has been calculated.

Normal Coordinate Treatment for the Out‐of‐Plane Vibrations of Ethylene‐Type Molecules

The s vectors for torsional and out‐of‐plane bending modes of vibration for ethylene‐type molecules are given. Then F‐ and G‐matrix elements are given for all ethylene‐type molecules with the exception of C2XYZW isomers. Finally, numerical calculations are carried out for C2H4, asymmetric C2H2F2, asymmetric C2H2Br2, the cis‐ and trans‐isomers of C2H2Cl2 and all of their deuterated analogs. The 57 out‐of‐plane fundamentals were calculated for the above 19 molecules. Of these 57 fundamentals 50 have been reported in the literature and are reproduced in this paper with an average deviation of 2.2 K or to 0.362% error.

Substituted Methanes. XX. Potential Constants and Calculated Thermodynamic Properties for Some Dibromomethanes

Using previous infrared and Raman data, a reasonable set of potential constants were obtained for CH2Br2 and CD2Br2, by means of the Wilson FG matrix method, with a potential energy function containing all possible second degree terms. Fundamental frequencies for CHDBr2 were then calculated using the potential constants found for CH2Br2 and CD2Br2. Finally the heat content, free energy, entropy, and heat capacity for the ideal gaseous state at 1 atmos pressure were calculated for these three molecules for twelve temperatures from 100°K to 1000°K with a rigid rotator harmonic oscillator approximation.

Substituted Methanes. XXVII. Potential Constants and Calculated Thermodynamic Properties for CH2F2, CHDF2, and CD2F2

Using the Wilson FG matrix method, potential constants were determined for the CH2F2 molecule using the most general quadratic potential function. The same constants were used to calculate the wave numbers of the fundamentals of the CHDF2 and CD2F2 molecules. Finally, the heat content, free energy, entropy, and heat capacity were calculated for all three molecules for 12 temperatures from 100° to 1000°K, for the ideal gaseous state at 1‐atmos pressure.

A note on the calculation of rotational distortion constants for axially symmetric ZX3Y molecules

Abstract A previous paper on the calculation of rotational distortion constants for some axially symmetric ZX3Y molecules is extended to include molecules in which the interbond angles are not tetrahedral.

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.

Substituted Methanes. XXI. Calculated and Observed Wave Numbers, and Calculated Thermodynamic Properties, for Bromodeuteromethane and Bromodideuteromethane

Using potential energy constants obtained from CH3Br and CD3Br, wave numbers (fundamentals) for CH2DBr and CHD2Br were calculated by means of the Wilson FG matrix method with a potential energy function containing all possible second degree terms. The calculated values of the wave numbers were then used to assign existing infrared and Raman spectral data for these molecules. Then the heat content, free energy, entropy, and heat capacity for the ideal gaseous state at 1 atmos pressure were calculated for 12 temperatures from 100 to 1000°K with a rigid rotator, harmonic oscillator approximation.

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.