ZIRCONOCENE DICHLORIDE

The alpha form of dichlorobis(eta(5)-cyclopentadienyl)zirconium, [ZrCl2(C5H5)(2)], crystallizes in space group P $($) over bar$$ 1 and is isomorphous with alpha-Cp(2)TiCl(2) and alpha-Cp(2)HfCl(2). The two Cl ligands and the centroids of the Cp rings adopt an irregular tetrahedral arrangement about the Zr center. The angle between the Cl-Zr-Cl plane and the Cp(centroid)-Zr-Cp(centroid) plane is 89.4 degrees for molecule (1) and 89.7 degrees for molecule (2) of the asymmetric unit. The average bond distances are C-C = 1.384 (5) and Zr-Cl = 2.447 (3) Angstrom in molecule (1), and C-C = 1.359 (7) and Zr-Cl = 2.447(1) Angstrom in molecule (2).