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 Pca2₁ with pseudo-mirror symmetry. Both molecules display a distorted tetrahedral geometry about the Ti atom. Each Ti is bonded in an η⁵ manner to the Cp ring of the isodiCp ligand, with Ti–ring centroid distances of 2.031 (2) and 2.013 (2) Å 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.

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