Three square-pyramidal complexes of dioxidovanadium(V) with
pyridoxalaminoguanidine (PLAG), of the formulas NH4[VO2(PLAG?2H)]?H2O (1),
VO2(PLAG?H) (2) and K[VO2(PLAG?2H)]?H2O (3) have been synthesized and
characterized by IR and UV-Vis spectral analysis and in case of 1 and 3 by
X-ray crystallography as well. The reaction of aqueous ammoniacal solution of
NH4VO3 and PLAG resulted in formation of 1, which in MeOH undergoes
spontaneous transformation into 2, which, in turn, in the reaction with KOH
transforms into 3. In these complexes PLAG is coordinated in a common
tridentate ONN mode, via phenoxide oxygen atom and nitrogen atoms of
azomethine and imino groups of the aminoguanidine fragment. In all previously
characterized complexes PLAG was coordinated in neutral form. However, here
we have proven that this ligand can be coordinated in both mono- (2) and
doubly deprotonated form (1 and 3) as well. [Projekat Ministarstva nauke
Republike Srbije, br. 172014].