The reaction of CpHfCl 3 •2THF with 2 equiv of (1,2,3-Me 3 allyl)MgBr or (1,1,2-Me 3 allyl)MgBr yields Cp(1,2,3-Me 3 allyl)(1,2-Me 2 butadiene)Hf (3) or Cp(1,1,2-Me 3 allyl)(2,3-Me 2 butadiene)Hf (4). X-ray crystallography of 3 shows that both the allyl and butadiene ligands assume a prone orientation with respect to Cp. Variable-temperature 1 H NMR studies indicate that compound 3 is static on the NMR time scale whereas 4 exists in two isomeric forms and undergoes three separate dynamic processes involving η 3 -η 1 isomerization at the unsubstituted and substituted ends of the allyl ligand [ΔG : =39.4±1.0 kJ/mol and 73.4±1.0 kJ/mol, respectively] and butadiene flip [ΔG : (avg)=49.8±10. kJ/mol]