Utilização do modelo CCFDF na interpretação das intensidades fundamentais das moleculas X IND. 2 CY e sua aplicação na regra da soma / Use of the CCFDF model in the interpretation of the fundamental intensities of the X IND. 2 CY molecules and its application in characteristic substituent shift model

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The QTAIM atomic charges and dipoles of X2CY (X = H, F, Cl; Y = O, S) molecules were determined from their optimized geometries. With these data the molecular dipole moments were calculated, showing good agreement with the experimental values in the literature and with the calculated values from the MP2/6-311++G (3d, 3p) wavefunction. The infrared fundamental intensities of the X2CY molecules were calculated and presented good agreement with experimental results already published and also with those obtained with the MP2 wavefunction. With the mean dipole moment derivatives of X2CY molecules decomposed into charge ? charge flux ? dipole flux contributions, the validity of the Characteristic Substituent Shift Model (CSSM) was verified for these three contributions. The results indicated good agreement of the CSSM in relation to the results obtained from the CCFDF/QTAIM model for all contributions. The CSSM for CCFDF contributions of the mean dipole moment derivatives of the CnHm, CHnXm (X= F, Cl), CFnClm, CX2 (X = S, O) e CX4 (X = F, Cl) molecules was also tested. The charge contributions showed better agreement with the ones of the CCFDF/QTAIM model than did the flux contributions for the carbon atom. For terminal atoms of theses molecules, the CSSM was not valid for the calculation of the mean dipole moment derivatives. Finally, comparison between results of the Gaussian 98 and Morphy programs showed that both are equally efficient for these X2CY molecules

ASSUNTO(S)

characteristic substituent shift model ccfdf derivadas medias dipole mean derivatives dipolo regra de soma

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