Synthesis, characterization and structural investigation of the first vanadocene(IV) carboxylic acid complexes prepared from the vanadocene dichloride

Two types of vanadocene complexes with carboxylic acids have been synthesized from the aqueous solution, Cp2V(OOCR)2 (R=H, CCl3 and CF3) and Cp2V(OOC–A–COO) (A= – and CH2), and characterized by EPR, IR, and Raman spectroscopy and X-ray diffraction analysis. Monocarboxylic and dicarboxylic acids form monodentate and chelate complexes, respectively. Both bonding types were evidenced by X-ray diffraction analysis. Structures and EPR HFC tensors were also calculated at the DFT level. Correlation between the complex structure and HFC tensor was established. HFC tensors are characteristic for the type of bond of carboxylic acid on vanadocene fragment. It is shown that the structure of complexes can be determined by the combination of theoretical method with experimental EPR spectra.