• Vanadium complexes;
  • Condensation reaction


The reactions between [VO(acac)2] (acac = acetylacetonate ion) or [VO(OPr)3] and trianionic tetradentate N,N-bis(2-methylene-4,6-alkylphenolate)aminoethanolate ligands, [L13– (4,6-dimethyl), L23– (4-methyl, 6-tert-butyl), L33– (4-tert-butyl, 6-methyl), L43– (4,6-di-tert-butyl)], afford mononuclear complexes [VO(L1)] (1) and [VO(L2)] (2) with a trigonal bipyramidal coordination sphere around the VV ion, or dinuclear octahedral complexes [V2O2(L3)2] (3) and [V2O2(L4)2] (4). In methanol an adduct with the formula [VO(L1)(MeOH)]·1/2MeOH (5) is obtained. According to multinuclear NMR spectroscopy all those complexes have a mononuclear structure in CDCl3 solutions. In wet polar solvents complex 1 reacts with water and N-dealkylation occurs producing 3,5-dimethylsalicyl alcohol, which condensates with 1 and forms a new oxidovanadium complex 6. An ether bond links 3,5-dimethylsalicyl alcohol to the L13– ligand. To support the reaction mechanism, we have found that in dry acetonitrile 1 reacts directly with salicyl alcohol forming compound 7, which is similar to 6. All compounds 17 have been characterized by elemental analysis, multinuclear NMR and X-ray diffraction.