119793-89-4Relevant academic research and scientific papers
Ring slip in associative reactions of some indenyl and phenylcyclopentadienyl iridium complexes
Habib, Afroze,Tanke, Robin S.,Holt, Elizabeth M.,Crabtree, Robert H.
, p. 1225 - 1231 (1989)
The complex ion [(η5-Ind)IrHL2]+ (Ind = indenyl, L = PPh3) undergoes substitution with t-BuNC, CO, and PMe3, while the Cp analogue (Cp = cyclopentadienyl) is inert. The phenylcyclopentadienyl complex [(η5-PhC5H4)IrHL2]+ undergoes rapid substitution with PMe3 but not with t-BuNC or CO. Slipped η3 and η1 intermediates are proposed in these reactions, and several examples of such complexes are detected by NMR at low temperatures. Deprotonation with n-BuLi takes place only for [(η5-Ind)IrHL2]+ and [(η5-PhC5H4)IrHL2]+, but not the Cp analogue. The reactions of the deprotonated complex [(η5-Ind)IrL2] with a number of electrophiles are also investigated and the resulting cations [(η5-Ind)IrXL2]+ (X = Me, Et, CH2Ph, Cl, I) characterized. The ethyl complex loses ethylene at 60°C by β-elimination, but only in donor solvents, which may attack associatively in the first step of the reaction. In nondonor solvents, the β-elimination is induced by UV photolysis, which may induce ring slip. Allyl bromide reacts with [(η5-Ind)IrL2] to give [(η5-Ind)Ir(η3-allyl)L]+, via [(η5-InD)Ir(η1-allyl)L2]+ as an observed but unisolated intermediate. The structure of the chloro complex [(η5-Ind)IrClL2] was determined by X-ray methods (space group P1; a = 11.314 (4) A?, b = 14.469 (5) A?, c = 13.021 (2) A?, a = 87.05 (2)°, β = 100.25 (2)°, γ = 68.43 (2)°; V = 1934.8 (10) A?3; mol wt = 954.2, Z = 2; F(000) = 944; ρcalcd = 1.638 g cm-3; R = 0.04 for 6379 reflections). Hydrogenation of [(η5-Ind)IrHL2]+ with Rh/C gives the tetrahydroindenyl complex.
