endo and exo isomers of isodicyclopentadienyltrichlorotitanium

The diastereomeric endo and exo isomers of the title complex, [TiCl3(C10H11)], have been synthesized by electrophilic attack of TiCl4 on the exo- or endo-trimethylsilyl derivative of isodiCp (isodiCp = isodicyclopentadiene). This reaction proceeds with net inversion of configuration to give exclusively either the endo- or exo-(isodiCp)TiCl3 compound. Although the two isomers have similar unit-cell constants, they crystallize in different space groups. The endo complex, (2), is in Pbcm with a crystallographic mirror plane, while the exo complex, (4), is in Pca2(1) with pseudo-mirror symmetry. Both molecules display a distorted tetrahedral geometry about the Ti atom. Each Ti atom is bonded in a eta(5) manner to the Cp ring of the isodiCp ligand, with Ti--ring centroid distances of 2.031 (2) and 2.013 (2) A for (2) and (4), respectively. A slight bending of the isodiCp ligand about the bond shared by the Cp ring and the norbornane fragment is observed in both structures. The determination of the absolute structure of (4) defines the directionality of the packing along the polar c axis.