An electrochemical investigation of the effects of antiaromaticity and determination of the increased antiaromatic destabilization of cyclobutenedione upon reduction
| Autor: | Reuben D. Rieke, C. Kenneth White, Lee D. Rhyne, Mark S. Gordon, Niegel P. Hacker, John F. W. McOmie |
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| Rok vydání: | 1977 |
| Předmět: |
chemistry.chemical_classification
Double bond Inorganic chemistry General Chemistry Ring (chemistry) Resonance (chemistry) Biochemistry Catalysis law.invention chemistry.chemical_compound Colloid and Surface Chemistry chemistry law Computational chemistry Molecule Molecular orbital Cyclobutadiene Electron paramagnetic resonance Antiaromaticity |
| Zdroj: | Journal of the American Chemical Society. 99:5387-5393 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja00458a026 |
| Popis: | Electrochemical studies were carried out on a series of cyclic 1,2-diones under nonaqueous conditions. From thereduction potentials and Hucke! molecular orbital calculations, the increase in antiaromatic destabilization of cyclobutenedione upon reduction is estimated to be at least 14 kcal/mol. The EPR spectrum of the radical anion of naphtho[b ]cyclobutadienoquinone is presented. Also, INDO calculations were carried out on several of the diones and the results are consistent with the experimental observations. Recently there has been considerable interest in small ring compounds possessing four electrons in a 1r system.Ic,2 Cyclobutadiene is the most studied member of this group of molecules. 1c There is evidence that the cyclic array of four electrons in a Hiickel basis set significantly destabilizes the molecule, and this destabilization is termed antiaromaticity.Ic,2 Owing to the instability of antiaromatic compounds, quantitative estimation of antiaromatic destabilization is difficult and few experimental estimates have been published. 1c Breslow and co-workers3 have oxidized hydroquinone anions electrochemically and reported the antiaromatic destabilization of cyclobutadiene to be 15-20 kcal/mol. Recently, Breslow and Sondheimer reported the reduction of some cyclobutenediones.3 In this paper we would like to present our attempt to measure the increase in antiaromatic destabilization of cyclobutenedione from the reduction potential of cyclic 1 ,2-diones (Figure 1). From classical resonance arguments, semidione (II) has increased double bond character between the carbonyl |
| Databáze: | OpenAIRE |
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