Artículos de revistas
Infrared vibrational intensities and polar tensors of the carbonyl and thiocarbonyl halides
Registro en:
Spectrochimica Acta Part A-molecular And Biomolecular Spectroscopy. Pergamon-elsevier Science Ltd, v. 53, n. 12, n. 2115, n. 2128, 1997.
1386-1425
WOS:A1997YH95300020
10.1016/S1386-1425(97)00142-X
Autor
Martins, HP
Bruns, RE
Institución
Resumen
The polar tensors of F2CO, Cl2CO, F2CS and Cl2CS have been determined from experimental infrared intensities. The sign ambiguities in the dipole moment derivatives were resolved by comparing alternative polar tensor solutions with the results of MP2/6-31G* molecular orbital calculations using bidimensional principal component projections of the polar tensor spaces. The signs chosen for the dipole moment derivatives are the same as those chosen in an earlier work where CNDO estimates were used for comparison. Signs for derivatives related to very small intensities (<0.5 km mol(-1)) were left undetermined. As already noted before the polar tensor for an atom of one of these carbonyl or thiocarbonyl halides can be estimated from the atomic polar tensors of the other three molecules. This is also true for the mean dipole moment derivatives and infrared intensity sums of these molecules. These simple relations can be explained if one assumes no saturation effect on the capacity of the carbon atom to donate electron density to the terminal atoms. Furthermore these simple relations appear to be extendable to the Is core electron energies of these molecules if the mean dipole moment derivative values are used as atomic charges in the simple potential model. (C) 1997 Elsevier Science B.V. 53 12 2115 2128