X-Ray Crystal Structures of Two Monopentamethylcyclopentadienylhafnium(IV) Complexes

The crystal structures of two monopentamethylcyclopentadienylhafnium(IV) derivatives have been determined by X-ray diffraction analysis. The [Hf(eta(5)-C5Me5)Cl-3] complex (I) crystallizes as a dimer in the monoclinic space group C2/c with Z = 8. The structure of I is described as two {Hf(eta(5)-C5Me5)Cl-2} units linked by two bridging chloride ligands. The [{Hf(eta(5)-C5Me5)Cl}(3)(mu-Cl)(4)(mu(3)-O)] complex (II) crystallizes in the monoclinic space group Cc with Z = 4. The structure of II is described as three {Hf(eta(5)-C5Me5)Cl} moieties connected by one or two bridging mu-chloride ligands and an additional mu(3)-oxide group. The hitherto unknown compound II has also been characterized by spectroscopic and analytical methods. In the solid state, the molecules of both derivatives are linked by C-H...Cl hydrogen bonds and C-H...pi interactions, providing an alternating layered pattern.