THE ISOMERIZATION CATALYST (C5H5)2TiCl2-LiAlH4. INFLUENCE OF THE NATURE OF UNSATURATED HYDROCARBONS ON THE CATALYST ACTIVITY

Article abstract of DOI:10.1016/0022-328X(84)80274-0

The reaction pathway between the components of the catalytic system Cp2TiCl2-LiAlH4-unsaturated hydrocarbon, depends considerably on the nature of the reaction medium.In dienes which are able to form stable η³-allyltitanocene derivatives, these represents the main reaction product; they are catalytically active in the double bond shifts.In dienes not forming stable η³-allyltitanocene derivatives and in α-olefins the catalytically-active η¹-alkenyl- and alkyl-titanocenes are transiently formed, deactivating rapidly to give the <(C5H5)(C5H4)TiHAlR2>2 complexes and minor amounts of η³-allyltitanocene derivatives in a side reaction involving intermolecular hydrogen transfer.In all α-olefinic hydrocarbons, the formation of alkyl-η¹-alkenyl- or η³-allyl-titanocene derivatives is preceded by the hydroalumination reaction, yielding Cp2TiCl2AlR2 complexes.In internal olefins, the hydroalumination reaction does not occur and the alkyltitanocenes which are formed catalyze the transformation of (Cp2TiCl)2 into μ-(η⁵ : η⁵-fulvalene)-di-μ-chlorobis(η⁵-cyclopentadienyltitanium), thus inducing the self-deactivation of the system.