Publications by authors named "Angel L Esteban"
The main aim of this work is to compare the transmission mechanisms for the Fermi contact term of spin-spin couplings, SSCCs, in series 1-X-bicyclo[1.1.1]-pentane, (1), and 1-X-3-methylbicyclo[1.
View Article and Find Full Text PDFHyperconjugative and electrostatic interactions effects on 1J(CH) spin-spin coupling constants (SSCCs) are critically studied from both theoretical and experimental points of view. A qualitative model is used to predict how the former affect such SSCCs, while electrostatic interactions are modeled with a point charge placed in the vicinity of the corresponding sigma(CH) bond. Hyperconjugative interactions are calculated using the "natural bond orbital" approach, and using the point-charge model, it is shown how intertwined are both types of interactions.
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- The study examines one- to three-bond 13C, 13C scalar couplings in pyrimidine derivatives using both experimental data and DFT calculations, focusing on four key contributions.
- It discusses the significance of non-contact terms and how substituent effects in pyrimidines compare to those in benzene and pyridine, with a dominance of the Fermi contact term in overall trends.
- Furthermore, while the inductive effect primarily influences 1J(C,C) couplings in benzene derivatives, this research highlights unique differences in pyrimidines, suggesting that nitrogen lone pair orientation can modify the impact of substituents on these couplings.
(13)C chemical shifts were measured for 18 1-X,3-CH(3)-bicyclo[1.1.1]pentanes and the corresponding (13)C substituent chemical shifts (SCSs) were compared with those measured previously for the corresponding 1-X-bicyclo[1.
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