The Parent Allene H2CCCH2 as an Allyl Ligand Precursor in Reactions with Bis(pentafulvene)titanium Complexes

Addition of the parent allene H2CCCH2 to the bis(pentafulvene)titanium complexes Ti1a,b results in the formal nucleophilic attack of one of the exocyclic quaternary carbon atoms (Cq,exo) of one pentafulvene ligand at the central propa-1,2-diene carbon atom to form the titanium complexes Ti2a,b bearing both one intact pentafulvene ligand and a bidentate cyclopentadienyl-/allyl-based ligand, whose functionalities are spaced by a C1 linker. Investigations into the nature of the Ti–allyl interaction is established by multinuclear NMR spectroscopy, single crystal X-ray diffraction, and combined computational studies. A first glimpse of the reactivity of Ti2a,b is demonstrated showing that both the intact pentafulvene ligand and the allyl unit can be modified.