A computational (DFT, MP2) and GIAO NMR study of substituent effects in benzenediazonium mono- and dications
15N and 13C NMR chemical shifts were computed by GIAO-DFT and GIAO-MP2 for a series of p-substituted benzenediazonium mono- and dications in order to probe the electronic effects of the substituents on the diazonium moiety. Optimized geometries and N/N vibrational frequencies werealso considered for...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2011 |
| País: | Argentina |
| Institución: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repositorio: | CONICET Digital (CONICET) |
| Idioma: | inglés |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/66343 |
| Acceso en línea: | http://hdl.handle.net/11336/66343 |
| Access Level: | acceso abierto |
| Palabra clave: | Cations Computer Chemistry Counter Ion Effects Density Functional Calculations Diazonium Cations Solvent Effects Substituent Effects https://purl.org/becyt/ford/1.4 https://purl.org/becyt/ford/1 |
| Sumario: | 15N and 13C NMR chemical shifts were computed by GIAO-DFT and GIAO-MP2 for a series of p-substituted benzenediazonium mono- and dications in order to probe the electronic effects of the substituents on the diazonium moiety. Optimized geometries and N/N vibrational frequencies werealso considered for comparison. The GIAO-DFT derived15N chemical shifts correlate more closely with the experimental values as compared to GIAO-MP2. Energyminimizations at the B3LYP/6-311+G(2d,p), M062X-6-311+G(2d,p), MP2/6-311+G(2d,p), G2(MP2), and CBS-Q levels were carried out. Relative dication stability order HCO+ > HOMe+ > HN(Me) 2+ > HOH+ > HCN+ > HNO 2+ was derived from isodesmic proton transfer reactions. The Nβ-protonated dications were less stable than the corresponding p-R+ dications. Among the regioisomeric N β-protonated dications (with R = -F, -Cl, and -CN), those with the R group in the para position were preferred. For the regioisomeric, ring-protonated benzenium-diazonium dications, the meta-protonated dications were more favored (by DFT and MP2). Influence of the counterion and solvent on the computed 15N NMR chemical shifts in PhN2+ X- were also assessed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. |
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