Phosphine–borane derivatives. 10. Vibrational spectra of the dimethylphosphine adducts of boron trihalides

1981 ◽  
Vol 59 (19) ◽  
pp. 2898-2908 ◽  
Author(s):  
John E. Drake ◽  
J. Lawrence Hencher ◽  
Layla N. Khasrou
Keyword(s):  
Structural Change ◽  
Solid State ◽  
Potential Energy ◽  
Force Field ◽  
Vibrational Spectra ◽  
Room Temperature ◽  
Field Model ◽  
Adduct Formation ◽  
Molecular Symmetry ◽  
Energy Distributions

The infrared (200–4000 cm−1) and Raman (0–3100 cm−1) spectra of (CH3)2PHBX3, (CH3)2PDBX3, and (CD3)2PHBX3, where X = Cl, Br, I, have been recorded in solid state and in solutions at room temperature. The fundamentals have been assigned on the basis of Cs molecular symmetry. A modified Urey–Bradley force field model has been used in calculating the frequencies and potential energy distributions as well as the force constants. The (P—B) force constant was found to be consistent with the structural change upon adduct formation.

Force field of acetic acid: use of CNDO/force calculations

1983 ◽  
Vol 61 (2) ◽  
pp. 263-266 ◽  
Author(s):  
A. Annamalai ◽  
Surjit Singh
Keyword(s):  
Acetic Acid ◽  
Potential Energy ◽  
Force Field ◽  
Force Fields ◽  
Force Constants ◽  
Energy Distributions ◽  
Valence Force Field ◽  
Bending Force ◽  
Set Up ◽  
Initial Force

The redundancy-free internal valence force field of monomeric acetic acid is evaluated using CNDO/force calculations and least-squares refinement. The initial force field is set up by taking the interaction and bending force constants from CNDO force field and transferring the stretching force constants from the force fields of chemically related molecules. Vibrational frequencies of monomeric CH3COOH, CH3COOD, CD3COOH, and CD3COOD are used to refine the force constants. The experimental force field thus obtained is found to be reasonable when compared to the force fields of related molecules as well as on the basis of the frequency fits and potential energy distributions.

Vibrational Spectra and Normal Coordinate Analysis of Disulfuryl Difluoride S2O5F2 and Diselenonyl Difluoride Se2O5F2

1993 ◽  
Vol 58 (3) ◽  
pp. 517-529 ◽  
Author(s):  
Jiří Toužín ◽  
Miloš Černík
Keyword(s):  
Raman Spectrum ◽  
Force Field ◽  
Raman Spectra ◽  
Infrared Spectra ◽  
Vibrational Spectra ◽  
Room Temperature ◽  
Normal Coordinate Analysis ◽  
Normal Coordinate ◽  
Valence Force Field ◽  
Overlapping Bands

Raman spectra (1 600 - 100 cm-1) of liquid S2O5F2 and Se2O5F2 and infrared spectra of liquid and gaseous S2O5F2 were measured. A modified general valence force field was used for their interpretation by normal coordinate analysis. Refinement of the number of lines in the Raman spectrum of S2O5F2 by means of numerical separation of the overlapping bands led to the conclusion that liquid S2O5F2 consists at least of three rotamers at room temperature.

Champ de force de valence et modes normaux de vibration de la glycylglycine et du monochlorhydrate monohydrate de glycylglycine

1974 ◽  
Vol 52 (14) ◽  
pp. 2590-2602 ◽  
Author(s):  
Christian Destrade ◽  
Eliane Dupart ◽  
Monique Joussot-Dubien ◽  
Chantal Garrigou-Lagrange
Keyword(s):  
Solid State ◽  
Force Field ◽  
Vibrational Spectra ◽  
Molecular Conformation ◽  
Normal Modes ◽  
Valence Force ◽  
Valence Force Field ◽  
Modes Of Vibration

The valence force field and normal modes of vibration of α-glycylglycine have been calculated using the vibrational spectra of ten isotopic derivatives, selectively labeled with deuterium or nitrogen-15. It is shown that this force field permits the determination of the frequencies of glycylglycine-hydrochloride in the solid state, despite a structure very different from that of the zwitterion. The agreement is particularly satisfying for those modes of vibration most sensitive to molecular conformation. It is thus possible to use this type of calculation to determine the conformation of an oligopeptide.

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