| Full text | |
| Author(s): |
Total Authors: 4
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| Affiliation: | [1] Univ Estadual Campinas, Inst Quim, CP 6154, BR-13083970 Campinas, SP - Brazil
[2] Univ Tecnol Fed Parana, Dept Engn Quim, Campus Ponta Grossa, Av Monteiro Lobato S-N, BR-84016210 Curitiba, Parana - Brazil
Total Affiliations: 2
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| Document type: | Journal article |
| Source: | Journal of Physical Chemistry A; v. 123, n. 30, p. 6482-6490, AUG 1 2019. |
| Web of Science Citations: | 0 |
| Abstract | |
Infrared band intensification of the A-H bond stretching mode of A-H center dot center dot center dot B acid-base systems has long been known to be the most spectacular spectral change occurring on hydrogen bonding. A QTAIM/CCTDP model is reported here to quantitatively explain the electronic structure origins of intensification and investigate the correlation between experimental enthalpies of formation and infrared hydrogen bond stretching intensifications amply reported in the literature. Augmented correlation-consistent polarized triple-zeta quantum calculations at the MP2 level were performed on complexes with HF and HCl electron acceptors and HF, HCl, NH3, H2O, HCN, acetonitrile, formic acid, acetaldehyde, and formaldehyde electron donor molecules. The A-H stretching band intensities are calculated to be 3 to 40 times larger than their monomer values. Although the acidic hydrogen atomic charge is important for determining the intensities of HF complexes relative to HCl complexes with the same electron donor, they are not important for infrared intensifications occurring on hydrogen bond formation for a series of bases with a common acid. Charge transfers are found to be the most important factor resulting in the intensifications, but dipolar polarization effects are also significant for each series of complexes. A mechanism involving intra-acid and intermolecular electron transfers as well as atomic polarizations is proposed for understanding the intensifications. The calculated sums of the intermolecular electron transfer and acid dipolar polarization contributions to the dipole moment derivatives for each series of complexes are highly correlated with their enthalpies of formation and H-bond intensifications. This could be related to increasing electron transfer from base to acid that correlates with the calculated hydrogen bonding energies and may be a consequence of the A-H bond elongation on complex formation having amplitudes similar to those expected for the A-H vibration. (AU) | |
| FAPESP's process: | 18/08861-9 - Application of the QTAIM / CCTDP model and machine learning for the forecast of chemical reactivities |
| Grantee: | Roy Edward Bruns |
| Support Opportunities: | Regular Research Grants |
| FAPESP's process: | 14/21241-9 - The inclusion of polarization effects in the description of amino acids and peptides through the use of atomic multipoles obtained from electron densities |
| Grantee: | Arnaldo Fernandes da Silva Filho |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |
| FAPESP's process: | 17/22741-3 - Using atomic multipoles and developing machine learning models to investigate transition states |
| Grantee: | Leonardo José Duarte |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |