American Journal of Applied Sciences | |
Intrahydrogen Bonding and Transition States Between Enol and Enethiol Tautomers in β-Thioxoketones | Science Publications | |
Bahjat A. Saeed1  Rita S. Elias1  Ebraheem A. Musad1  | |
关键词: β-thioxoketones; density functional theory; intrahydrogen bonding; reaction barrier; Transition State (TS); tautomeric mixture; basis sets; enethiol; ringlike structure; isolatedmolecule conditions; harmonic analyses; | |
DOI : 10.3844/ajassp.2011.762.765 | |
学科分类:自然科学(综合) | |
来源: Science Publications | |
【 摘 要 】
Problem statement: Hydrogen bonding is one of the most important concepts in chemistry because it is crucial to understand many different interactions both in gas phase and in condensed media. A particular subset is presented by the intramolecular hydrogen bonds where two ends of the same molecule interact, resulting in a ringlike structure. Approach: The study involved theoretical investigation of proton transfer and transition states in β-thioxoketones. Both structures of the enol and enethiol tautomers of β-thioxoketones were geometrically optimized then the transition states were obtained. The calculations were done at the B3LYP hybrid and 6-31G(d,p), 6-31+G(d,p), 6- 31++G(d,p), 6-311G(d,p), 6-311+G(d,p) and 6-311++G(d,p) basis sets. Results: The calculated energies of the enethiol tautomer are higher than those of the enol tautomer for all the thioxoketones studied in this work. The S...O distances are in the order: enethiol > enol > transition state in addition the hydrogen bonding in the enol tautomer is stronger than that in the enethiol tautomer. Conclusion: The interconversion within the tautomeric mixture in these compounds is preferable in the enethiol → enol direction.
【 授权许可】
Unknown
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