Hafnium tetrafluoride
Hafnium tetrafluoride is the inorganic compound with the formula HfF4. It is a white solid.  It adopts the same structure as zirconium tetrafluoride, with 8-coordinate Hf(IV) centers.

Hafnium tetrafluoride forms a trihydrate, which has a polymeric structure consisting of octahedral Hf center, described as n(H2O)n and one water of crystallization.  In a rare case where the chemistry of Hf and Zr differ, the trihydrate of zirconium(IV) fluoride has a molecular structure , without the lattice water.

References

Further reading
Benjamin, S. L., Levason, W., Pugh, D., Reid, G., Zhang, W., "Preparation and structures of coordination complexes of the very hard Lewis acids ZrF4 and HfF4", Dalton Transactions 2012, 41, 12548. 

Hafnium compounds
Fluorides
Metal halides