Vanadocene and niobocene dihalides containing electron-withdrawing substituents in the cyclopentadienyl rings: Synthesis, characterization and cytotoxicity

The first example of the group V metallocene dihalides substituted in the cyclopentadienyl rings with electron-withdrawing substituents is reported. This study includes synthesis and spectroscopic characterization of the series of vanadocene and niobocene compounds functionalized in the cyclopentadienyl rings with the ester groups. Structures of (η5-C5H4COOPh)2VCl2, (η5-C5H4COOMe)2VBr2·CH2Cl2, (η5-C5H4COOPh)2NbCl2, (η5-C5H4COOMe)2NbBr2 and (η5-C5H4COOEt)2NbBr2 were determined by X-ray diffraction analysis. Cytotoxic activity toward human leukemia cells MOLT-4 was established in vitro for all newly prepared metallocene compounds.