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Kinetics and mechanism of nucleophilic substitutions on coordinated polyenes and polyenyls. 3. Activation of eta(5)-cyclopentadienyl ligands toward nucleophilic attack through eta(5)->eta(3) ring slippage and a comparison with reaction at C5H4Oстатья
Информация о цитировании статьи получена из
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 16 ноября 2017 г.
- Авторы: Simanko W., Tesch W., Sapunov VN, Mereiter K., Schmid R., Kirchner K., Coddington J., Wherland S.
- Журнал: Organometallics
- Том: 17
- Номер: 26
- Год издания: 1998
- Издательство: American Chemical Society
- Местоположение издательства: United States
- Первая страница: 5674
- Последняя страница: 5688
- DOI: 10.1021/om980701t
- Аннотация: Complexes of the types [Ru(eta(5)-C5H5)(eta(4)-C5H4O)](2)(CF3SO3)(2) (1) and [Ru(eta(5)-C5H5)(eta(4)-C5H4O)(L)]CF3SO3 (L = CH3CN (2), pyridine (3), thiourea (4)) react with tertiary phosphines to give (i) 1,1'- (12) or (ii) 1,2-disubstituted ruthenocenes (13) depending primarily on the basicity of the entering phosphine and the nature of L. Path i proceeds via the intermediacy of [Ru(eta(3)-C5H5)(eta(4)-C5H4O)(PR3)](2)(2+) (5) and [Ru(eta(3)-C5H5)(eta(4)-C5H4O)(PR3)(L)](+) (6-8); i.e., the hapticity of the C5H5 ligand is changed from eta(5) to eta(3) while forming an additional Ru-P bond. The eta(3) bonding mode was established by H-1 and C-13{H-1} NMR spectroscopies. The kinetics of these reactions were studied in detail, providing enthalpies and entropies of both activation and reaction. The conversions to 6-8 are exothermic (Delta H degrees = -5.5 to -16.9 kcal mol(-1)) but entropically unfavorable (Delta S degrees = -44.8 to -19.0 cal K-1 mol(-1)). The activation parameters and rate constants vary little with the phosphine, suggesting a preequilibrium between eta(5) and eta(3) species of the starting complexes where the latter reacts with the entering phosphine in the rate-determining step. The new eta(3)-C5H5 complexes are, with the exception of 5, fluxional in solution due to an intramolecular enantiomeric equilibrium likely proceeding through a five-coordinate eta(1)-C5H5 intermediate. Path ii proceeds via eta(3)-cyclopentenoyl complexes of the type [Ru(eta(5)-C5H5)(eta(3)-C5H4O-2-PR3)(L)](+) (9-11). Furthermore, 3 and 4 react with small and basic phosphines PR3 = PMe3 and Me2PCH2PMe2 to give the half-sandwich complexes [RU(eta(5)-C5H4OH)(PR3)(2)L](+) (14, 15) together with free C5H4PR3 (16).
- Добавил в систему: Сапунов Валентин Николаевич