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: v(V = 0) congruent to 961 cm(-1); EPR: g congruent to 1.980) or for polymers (IR: v(V = 0) about 890 cm(-1); EPR: g(x) = g(y) = 1.975(5), g(z) = 1.960(2),A(x) = A(y) = 40(5), A(z) = 160(3) x 10(-4) cm(-1)). The polymeric structure results from intermolecular V = 0 ... V = 0 interactions.