Structural and thermodynamic aspects of the dissociation of cyclopentadienyl rings from homoleptic cyclopentadienyl early transition metal, cerium, and thorium derivatives

► For Cp4M the S4 structures are saddle points. ► The minima for Cp4M have all η5-Cp rings for M = Ce and Th, three η5-Cp rings and one η1-Cp ring for M = Zr, and two η5-Cp rings and two η5-Cp rings for M = Ti and Hf. ► The dissociation energies for Cp4M → Cp3M + Cp increase in the sequence Ti < Ce < Zr ∼ Hf < Th. ► The C3h structures with all η5-Cp rings are genuine minima for all of the Cp3M compounds except for Cp3Ti. ► The dissociation energies for Cp3M → Cp2M + Cp increase in the sequence V < Ti < Sc < Y < La.