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Thermal and long period stability of series of V(V), V(IV) and V(III) complex with Schiff base ligands in solid state

Szklarzewicz Janusz, Jurowska Anna, Hodorowicz Maciej, Gryboś Ryszard

Science, Technology and Innovation

2019

Vol. 4, no. 1

30--36

The synthesis and physicochemical properties of three new complexes of vanadium at +5, +4 and +3 oxidation state are described and discussed. The octahedral surrounding of vanadium for V(III) complexes of [V(L1)(HL1)] general formula is filled with two ONO tridentate ligand L, for V(IV) one ONO ligand L, oxido ligand and 1,10-phenanthroline (phen) as a co-ligand are presented in complexes of [VO(L2)(phen)]. For V(V) the complexes of [VO2(L1)(solv)] type were formed. As ligands, the H2L Schiff bases were formed in reaction between 5-hydroxysalcylaldehyde and phenylacetic hydrazide (H2L1) and 3,5- dichlorosalicyaldehyde and 4-hydroxybenzhydrazide (L2). The magnetic moment measurements, in 8 year period, show, that V(III) complexes slowly oxidise to V(IV) with preservation of the nonoxido character of the complexes, while V(IV) complexes were found to be stable. The TG and SDTA measurements indicate, that thermal stability depends mainly on the oxidation state of vanadium. The less thermally stable are the V(V) complexes, while V(IV) and V(III) are stable up to ca. 200oC. In solution, at pH 2 (similar to that in human digestion system), again the V(IV) are the most stable, only at pH 7.0 V(III) complexes had higher stability. The most stable, thus best for pharmaceutical use, are V(IV) complexes.

Theoretical simulation of the infrared spectrum of salicylaldehyde

Boczar M., Wójcik M. J., Szczeponek K., Jamróz D., Ikeda S.

Bulletin of the Polish Academy of Sciences. Chemistry

2002

Vol. 50, No. 1

11-14

Theoretical simulation of the v(s) stretching band is presented for salicylalde-hyde taking into account an adiabatic coupling between the high-frequency O-H stretching and the low-frequency intramolecular O...O stretching modes, linear and quadratic distortions of the potential energy for the low-frequency vibration in the excited state of the O-H stretching vibration and resonance interaction between the O-H and the C-H stretching vibrations in the hydrogen-bonded ring.