The crystal structure of dicyclopentadienylvanadium monochloride and its implications for the structures of other d2 dicyclopentadienyl compounds

The crystal structure of dicyclopentadienylvanadium(III) monochloride, (η⁵-C₅H₅)₂VCl, has been solved by the X-ray diffraction heavy atom method. The compound crystallizes in the orthorhombic space group Ama2 with cell parameters a 9.134(8), b 13.522(10), and c 7.484(6) Å; ?_obs 1.55(1) g/cm³, ?_calc 1.56 g/cm³ for Z = 4. Full matrix least squares refinement based on 760 reflections lead to agreement factors of R = 0.054 and R_ω = 0.069. The structure confirms that (η⁵-C₅H₅)₂VCl is monomeric in contrast to (η⁵-C₅H₅)₂ScCl]₂ and η⁵-C₅H₅)₂TiCl]₂, which are dimeric. In the solid state the molecule possesses a crystallographic mirror plane of symmetry. The chlorine atom resides symmetrically in the open face of the (η⁵-C₅H₅)₂V⁺ group with a VCl bond distance of 2.390(4)Å. The average vanadium to carbon interatomic distance is 2.28(2) Å. The structure is discussed in terms of the electronic properties of d² compounds with structures (η⁵-C₅H₅)₂VX and η⁵-C₅H₅)₂VY₂]⁺.