Reaction of Pentafulvene Titanium and Zirconium Complexes with Phosphorus Ylides: Stoichiometric Reactions and Catalytic Intramolecular Proton Shuttles

Abstract

The reaction of penta- and benzofulvene complexes of group 4 (M = Ti, Zr) with different phosphorus ylides is reported. Employing the bis(η5:η1-pentafulvene)titanium complexes Ti1a and Ti1b, the reactions with the corresponding phosphorus ylides Y1–5 result in a spontaneous single C–H bond activation and metallocene ylide complexes Ti2a–e can be isolated in good yields. On the basis of these results, this reactivity pattern has been extended to the mono(η5:η1-pentafulvene) and -benzofulvene complexes Ti3, Zr1a,b, and Zr1a,b-benzo. Transferring this to the titanium complex Ti3, an additional equilibrium between the reaction product (η5-C5Me5)(η5-CpAd)Ti(Cl)CHPPh3 (Ti4a) and the corresponding “tuck-in” complex (η5:η1-C5Me4CH2)(η5-CpAd)TiCl (Ti4b) can be observed. In Ti4b, a methyl group of the Cp*-ligand is activated by the coordinated phosphorus ylide. Using this intramolecular C–H activation, Ti4b can be synthesized by catalytic amounts (3 mol %) of the phosphorus ylide Y1 in quantitative yield. Subsequen...