REACTIONS OF HYDRIDO(CYCLOOCTA-1,5-DIENE)TRIS(PHOSPOHINE)RUTHENIUM(II) CATIONS WITH 1,3-DIENES: FORMATION OF AGOSTIC η3-ENYL SPECIES 3-ENYL)l3>+

Article abstract of DOI:10.1016/0022-328X(85)88010-4

Treatment of either the hydrido-diene complexes (cod=cycloocta-1,5-diene, L=PMe3, PMe2Ph, P(OMe)Ph2) or the isomeric cyclooctenyl species 3-C8H13)L3> with 1,3-dienes gives the corresponding η³-enyl cations 3-heptenyl)L3>⁺, 3-hexenyl)L3>⁺ and 3-butenyl)(PMe2Ph)3>⁺.The products contain an aliphatic C-H...Ru interaction and exhibit four distinct fluxional processes as revealed by variable temperature NMR studies: mutual exchange of the phosphorus donor ligands< a 1,2-metal migration around the endo face of the carbocyclic ring; an exchange involving C-H interaction at the metal, and in the case of the butenyl complex, methyl group rotation.Whereas the first two processes are of relatively high energy and can be frozen out at low temperatures, the remaining processes are still rapid at the lowest temperature investigated (183 K), except for the complex 3-cycloheptenyl)-(P(OMe)2Ph)3>⁺ which gave a slow-exchange 1H-NMR spectrum at 500 MHz.