Radical Cation of a Trimethylenemethane with a Nondegenerate Ground State
| ISSN: | 1520-5126 0002-7863 |
|---|---|
| DOI: | 10.1021/ja046961l |
| Přístupová URL adresa: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::3f8bcc5d61aca977c432ecda319f698e https://doi.org/10.1021/ja046961l |
| Přírůstkové číslo: | edsair.doi.dedup.....3f8bcc5d61aca977c432ecda319f698e |
| Autor: | Daniel Frank, A. De Meijere, Fabian Gerson, Alexander Maltsev, Thomas Bally |
| Rok vydání: | 2005 |
| Předmět: |
Stereochemistry
Trimethylenemethane Matrix isolation General Chemistry Ring (chemistry) Biochemistry Catalysis law.invention chemistry.chemical_compound Crystallography Colloid and Surface Chemistry chemistry Unpaired electron Radical ion law Yield (chemistry) Electron paramagnetic resonance Ground state |
| Zdroj: | Journal of the American Chemical Society. 127:1983-1988 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja046961l |
| Popis: | Upon ionization by gamma-irradiation in frozen CFCl(3), or by X-irradiation in an Ar matrix, 2,2,3,3-tetramethylmethylenecyclopropane (MCP-Me4) readily undergoes ring opening to yield the radical cation of 1,1,2,2-tetramethyltrimethylenemethane (TMM-Me4). The hyperfine-coupling constants for TMM-Me4(.+) are (mT) -1.99 (2H), +0.53 (6H), and +0.19 (6H), and the singly occupied orbital closely resembles one of the two degenerate nonbonding pi-MOs (NBMOs) of trimethylenemethane (TMM). Due to the expected effect of the methyl substituents, this "symmetric" NBMO, psi(2+) (b(1)), is energetically favored relative to its "antisymmetric" counterpart, psi(2-) (a(2)), so that the ground state assumes a structure with (2)B(1) symmetry in the C(2v) point group. Calculations show that the ring opening in the primary radical cation MCP-Me4(.+) to yield TMM-Me4(.+) is spontaneous, whereas in the parent system (MCP(.+) --> TMM(.+) a low barrier does exist. In contrast to the previously investigated case of the radical cation of tetramethyleneethane, the "electromer" of TMM-Me4(.+), in which the unpaired electron occupies psi(2-), cannot be attained photochemically. |
| Databáze: | OpenAIRE |
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