π-Olefin-Iridium-Komplexe, XVIII [1] Reaktionen von Bis[cycloocta-1,5-dien-μ-chloro-iridium] mit n-Propyllithium in Gegenwart von Alkinen / π-Olefin Iridium Complexes, XVIII [1]Reactions of Bis[cycloocta-l,5-diene-μ-chloro-iridium] with n-Propyllithium in the Presence of Alkynes

Abstract

The reaction of [(cod)IrCl]2 (cod = η4-cycloocta-1,5-diene) with n-C3H7Li gives non-isola-ble (cod)IrH species by β-elimination of (cod)Ir-n-C3H7 intermediates; the stable final products of further reactions with RC = CR highly depend on the nature of the substituents R. With R = Me the 6-endo-H-hexamethylcyclohexadienyl complex 1 is obtained together with the iridacyclopentadienyl compound 2 and known {[(cod)IrH]4C3H4) (3). In case of R = Et steric effects cause transfer of the hydridic hydrogen to the cod ligand, and the hexaethylbenzene species 4 is isolated which was characterized by crystal structure analysis. The reaction system with tolane again yields a 6-endo-H-cyclohexadienyl complex (5). In all cases free substituted benzenes are formed as cyclotrimerization products of the alkynes.