Synthesis, Structure, and Reactivity of C 2-Symmetric Bis(phospholyl)zirconium and Bis(phospholyl)hafnium Complexes

Several C 2-symmetric bis(phospholyl) adducts of group 4 metals, including the first example of an η5-phospholyl complex of hafnium, have been synthesized and structurally characterized. These complexes undergo rac/meso isomerization in a process that is accelerated by Lewis bases. A C 2-symmetric bis(phospholyl)zirconium dichloride binds as a bidentate ligand to Mo(CO)4. In the presence of methylalumoxane, bis(phospholyl)zirconium complexes serve as active catalysts for ethylene−hexene copolymerization reactions.