Vanadocene dichloride

Vanadocene dichloride, dichlorobis(η5-2,4-cyclopentadien-1-yl) vanadium, or dicyclopentadienyl vanadium dichloride is (η5-C5H5)2VCl2 (commonly abbreviated as Cp2VCl2). It is a close relative of titanocene dichloride but with one additional valence electron, hence Cp2VCl2 is paramagnetic. Vanadocene dichloride is a useful precursor to other (C5H5)2V compounds.

Preparation
Cp2VCl2 was first prepared by Wilkinson and Birmingham via the reaction of NaC5H5 and VCl4 in THF, followed by work up by extraction with chloroform and hydrogen chloride and recrystallization from toluene.

Structure
Like its Ti analogue, vanadocene dichloride is currently being investigated as a potential anticancer drug (currently in clinical trials). The mechanism by which it acts is not understood, but some conjecture that it might be due to its interactions with the protein transferrin.