New vanadyl complexes with metformin derivatives as potential insulin mimetic agents

Three new complexes with formula [VOL2]·xH2O [(1) HL: N,N-dimethylbiguanide, x = 0.5; (2) HL: 1-phenylbiguanide, x = 0; (3) HL: 1-(o-tolyl)biguanide, x = 0.5] were synthesised and characterised. The IR and UV–Vis spectral data indicate that these biguanide derivatives act as bidentate chelating anionic ligands and generate VO(II) complexes with a square–pyramidal stereochemistry. The thermal analysis (TG, DTA) elucidated the composition and also the number and nature of the water molecules.