Monomeric and polymeric oxovanadium(IV) complexes containing 5-(4′-alkyl-phenylazo)-8-hydroxy-quinoline ligands

A number of bis-[5-(4′-R-phenylazo)-8-hydroxy-quinolinato] vanadyl(IV) compounds (R=H, CH3, C2H5, n-C3H7, n-C4H9) have been synthesized and characterized by elemental analyses and IR, EPR and UV–Vis spectroscopies. Data from the above show that they exist in two isomeric solid forms (which were separated for R=C2H5, n-C3H7 and n-C4H9) whose IR and EPR spectra account for isolated molecules (IR: ν(VO)≅961 cm−1; EPR: g≅1.980) or for polymers (IR: ν(VO) about 890 cm−1; EPR: gx=gy=1.975(5), gz=1.960(2), Ax=Ay=40(5), Az=160(3)×10−4 cm−1). The polymeric structure results from intermolecular VO⋯VO interactions.