Hafnocene dichloride
Hafnocene dichloride is the organohafnium compound with the formula . It is a white solid that is sparingly soluble in some organic solvents. The lighter homologues zirconacene dichloride and titanocene dichloride have received much more attention. While hafnocene is only of academic interest, some more soluble derivatives are precatalysts for olefin polymerization. Moreso than the Zr analogue, this compound is highly resistant to reduction. It is prepared by a salt metathesis reaction from hafnium tetrachloride by salt metathesis:

Derivatives
Hydrolysis gives the trimer . The chloride ligands can be replaced by other halides. The bis(phosphide)  can be prepared by salt metathesis from hafnocene dichloride. References

Metallocenes

Metal halides
Chloro complexes
Cyclopentadienyl complexes
Hafnium compounds