New 1,1′-Ring-substituted Vanadocene Dichlorides. Crystal structures of [V(η5-C5H4SiMe3)2Cl2] and [V(η5-C5H5)2Cl2]

The 1,1′-ring-substituted vanadocene dichlorides V(η⁵-C₅H₄R)₂Cl₂] (R = CMe₃, SiMe₃, SiEt₃) have been prepared from VCl₄ and the appropriate lithiated cyclopentadiene, C₅H₄RLi, in 1 : 2 ratios. All complexes were characterized by elemental microanalysis and IR spectroscopy. The crystal structures of V(η⁵-C₅H₄SiMe₃)₂Cl₂] 3 and the parent compound V(η⁵-C₅H₅)₂Cl₂] 1 have been determined by X-ray diffraction and are in accordance with expectations. Compound 1 crystallizes with two crystallographically independent molecules in its monoclinic unit cell. These two molecules are quite similar in their essential structural features. Compound 3 crystallizes in the triclinic space group P1 . The trimethylsilylcyclopentadienyl rings are bound in a staggered relative orientation.