Characteristic Substituent Effect Model for the Infrared Intensities of the X2CY (X = H, F, Cl, Br; Y = O, S) Molecules

Autor(es)

Duarte, Leonardo J. ; Richter, Wagner E. ; Bruns, Roy E.

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry A; v. 127, n. 14, p. 9-pg., 2023-04-13.

Resumo

Many years ago, the gas-phase infrared fundamental intensities of Cl2CS were determined within experimental error from the experimental substituent shift relationship between atomic polar tensors of these molecules formed the basis for these calculations. Here, QCISD/cc-pVTZ-level Quantum Theory of Atoms In Molecules (QTAIM) individual charge, charge transfer, and polarization contributions to these atomic polar tensor elements are shown to obey the same basic relationship for the extended X2CY (Y = O, S; X = H, F, Cl, Br) family of molecules. QTAIM charge and polarization contributions, as well as the total equilibrium dipole moments of the X2CY molecules, also follow this characteristic substituent shift model. The root-mean-sqaure error for the 231 estimates of these parameters is 0.14 e or only about 1% of the total 10 e range of the Atomic Polar Tensor (APT) contributions determined from the wave functions. The substituent effect APT contribution estimates were used to calculate the infrared intensities of the X2CY molecules. Although one serious discrepancy was observed for one of the CH stretching vibrations of H2CS, accurate values were within 45 km center dot mol-1 or about 7% of the 656 km center dot mol-1 intensity range predicted by the QCISD/cc-pVTZ wave functions. Hirshfeld charge, charge transfer, and polarization contributions are also found to follow this model, although their charge parameters do not follow electronegativity expectations. (AU)

• Processo FAPESP: 18/08861-9 - Aplicação do modelo QTAIM / CCTDP e machine learning para a previsão de reatividades químicas
• Beneficiário: Roy Edward Bruns
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 17/22741-3 - Uso de multipolos atômicos e desenvolvimento de modelos de machine learning na investigação de estados de transição
• Beneficiário: Leonardo José Duarte
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto