Allylation of cobalt-co-ordinated cyclo-octatetraene by the [fe{P(OMe)3}(NO)2(η3-allyl)] cation: Ring closure to 1,2,3,3a-tetrahydropentalenyl derivatives and the X-ray structure of [co(η5-C8H8R)(η-C5Me 5)][PF6] [r = CH2C(Me)=CH2]

Abstract

The reaction of [Fe{P(OMe)3}(NO)2(η3-allyl)][PF 6] [1; allyl = CH2CHCH2, CH2CHCHMe, or CH2C(Me)CH2] with [Co(η4-cot)(η-C5R′5)] (2; R′ = H or Me, cot = cyclo-octatetraene) results in C-C coupling and the formation of 1,2,3,3a-tetrahydropentalenyl derivatives [Co(η5-C8H8R)(η-C 5R′5)][PF6] [3; R = CH2CH=CH2, CH2CH=CHMe, or CH2C(Me)=CH2; R′ = H or Me]. An X-ray diffraction study on [Co(η5-C8H8R)(η-C5Me 5)][PF6] [R = CH2C(Me)=CH2] confirms the structure assignment with the cobalt atom co-ordinated to an η5-1,2,3,3a-tetrahydropentalenyl ligand having the 2-methylallyl substituent exo to the metal. The co-ordination of the η5-1,2,3,3a-tetrahydropentalenyl ligand is slightly asymmetric with the subs..