Allylic alkylation of complexed cyclo-octatetraene (cot) via the reaction of [Fe{P(OMe)3}(NO)23-allyl)]+ with [M(CO)34-cot)] (M = Fe or Ru) derivatives; X-ray structure of [Ru(CO)2(PPh3)(η23-C 8H8R)][PF6]·0.5CH...

Neil G. Connelly, Mark Gilbert, A. Guy Orpen, John B. Sheridan

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Abstract

Title full: Allylic alkylation of complexed cyclo-octatetraene (cot) via the reaction of [Fe{P(OMe)3}(NO)23-allyl)]+ with [M(CO)34-cot)] (M = Fe or Ru) derivatives; X-ray structure of [Ru(CO)2(PPh3)(η23-C 8H8R)][PF6]·0.5CH2Cl 2 [R = CH2C(Me)=CH2]. The reaction of [Fe{P(OMe)3}(NO)23-allyl)][PF 6] [1; allyl = CH2CHCH2 or CH2C(Me)CH2] with [Ru(CO)2L(η4-cot)] (L = CO or PPh3, cot = cyclo-octatetraene) gives [Ru(CO)2L(η23-C8H 8R)][PF6] [2; R = CH2CH=CH2 or CH2C(Me)=CH2] whereas that of (1; allyl = CH2CHCHMe) yields [2; R = CH(Me)CH=CH2], as a mixture of two diastereomers, and (2; R = CH2CH=CHMe). The X-ray structure of [2; R = CH2C(Me)=CH2] shows that the addition of the 2-methylallyl group to the C8 ring yields the exo isomer, and confirms that the resulting cyclo-octatrienyl ligand is η23-co-ordinated to ruthenium. The η2-alkene unit is trans to the PPh3 ligand, and the η3-allyl moiety is transoid to the two carbonyl ligands. Complex (1) and [Fe(CO)2(CNBut)(η4-cot)] give [Fe(CO)2(CNBut)(η5-C8H 8R)][PF6] as a mixture of cyclo-octatrienyl (3) and bicyclo[5.1.0]octadienyl (4) isomers, the former showing rotamerism of the Fe(CO)2(CNBut) group with respect to the η5-bound hydrocarbon; diastereomerism is observed for [3; R = CH(Me)CH=CH2]. The cationic iron and ruthenium complexes (2)-(4) are deprotonated by NEt3 in CH2Cl2 to give the allyl-substituted cot complexes [M(CO)2L(η4-C8H7R)] [5; M = Fe, L = CNBut, R = CH2CH=CH2, CH2C(Me)=CH2, CH(Me)CH=CH2, or CH2CH=CHMe; M = Ru, L = PPh3, R = CH2C(Me)=CH2] which undergo two dynamic processes in solution, namely rotamerism (M = Fe) and oscillation of the M(CO)2L unit with respect to the η4-bound hydrocarbon. The compounds [Fe(CO)2(CNBut)(η4-C8H 7R)] [R = CH2CH=CH2orCH2C(Me)=CH2] react sequentially with [1; R = CH2CHCH2 or CH2C(Me)CH2] and NEt3 to give the difunctionalised cyclo-octatetraene derivatives [Fe(CO)2(CNBut)(η4-C8H 6R2)] [6; R = CH2CH=CH2 or CH2C(Me)=CH2]. The substituted cyclo-octatetraenes C8H7[CH2C(Me)=CH2] and C8H6[CH2C(Me)=CH2]2 are detached from the appropriate iron complexes, (5) or (6), on reaction with ONMe3·2H2O.

Original languageEnglish (US)
Pages (from-to)1291-1300
Number of pages10
JournalJournal of the Chemical Society, Dalton Transactions
Issue number4
DOIs
StatePublished - 1990
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

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