CEJC 3(1) 2005 157–168 Synthesis, characterization and structure of the Bis(methyl-cyclopentadienyl)vanadium(IV) carboxylates Jarom´ır Vinkl´arek1∗, Jan Honz´ıˇcek1, Ivana C´ısaˇrov´a2, Martin Pavliˇsta3, Jana Holubov´a1 1 The Department of General and Inorganic Chemistry, University of Pardubice, n´am. Cs.ˇ legi´ı565, 532 10 Pardubice, Czech Republic 2 Department of Inorganic Chemistry, Charles University, Hlavova 2030, 128 40 Prague 2, Czech Republic 3 Research Centre “New Inorganic Compounds and Advanced Materials”, University of Pardubice, n´am. Cs.ˇ legi´ı565, 532 10 Pardubice, Czech Republic Received 1 July 2004; accepted 18 November 2004 Abstract: The 1,1’-dimethylvanadocene dichloride ((C5H4CH3)2VCl2) reacts in aqueous solution with various carboxylic acids giving two different types of complexes. The 1,1’- dimethylvanadocene complexes of monocarboxylic acids (C5H4CH3)2V(OOCR)2 (R = H, CCl3, CF3, C6H5) contain two monodentate carboxylic ligands, whereas oxalic and malonic acids act as chelate compounds of the formula (C5H4CH3)2V(OOC-A-COO) (A= –, CH2). The structure of the (C5H4CH3)2V(OOCCF3)2 complex was determined by single crystal X-ray diffraction analysis. The isotropic and anisotropic EPR spectra of all the complexes prepared were recorded. The obtained EPR parameter values were found to be in agreement with proposed structures. c Central European Science Journals. All rights reserved. Keywords: bent metallocene, 1,1’-dimethylvanadocene dichloride, antitumor agent, EPR spectroscopy, X-ray diffraction analysis ∗ E-mail:
[email protected] 158 J. Vinkl´arek et al. / Central European Journal of Chemistry 3(1) 2005 157–168 1 Introduction The titanocene- and vanadocene dichlorides, (C5H5)2MCl2(M = Ti, V), exhibit anti- tumor activity for a wide variety of human tumors with reduced toxicity [1-4].