Oxidovanadium(V) Complexes with Aminoethanol Bis(phenolate) [O,N,O,O′] Ligands: Preparations, Structures, N ‐Dealkylation and Condensation Reactions

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, [L1 3– (4,6‐dimethyl), L2 3– (4‐methyl, 6‐ tert ‐butyl), L3 3– (4‐ tert ‐butyl, 6‐methyl), L4 3– (4,6‐di‐ tert ‐butyl)], afford mononuclear complexes [VO(L1)] ( 1 ) and [VO(L2)] ( 2 ) with a trigonal bipyramidal coordination sphere around the V V ion, or dinuclear octahedral complexes [V 2 O 2 (L3) 2 ] ( 3 ) and [V 2 O 2 (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 CDCl 3 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 L1 3– 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 1 – 7 have been characterized by elemental analysis, multinuclear NMR and X‐ray diffraction.