Proton transfer and coordination properties of aromatic α-hydroxy hydrazones

The prototropic properties of two nitro derivatives of aromatic α-hydroxy hydrazones 2,4-dinitro-N-phenyl-N′(2-hydroxy-1-phenylmethylene hydrazine) and 2,4-dinitro-N-phenyl-N′(2-hydroxy-1-naphthylmethylene hydrazine] have been analysed through electronic absorption, ¹H and ¹³C NMR and semiempirical molecular orbital methods. The metal binding properties of both compounds and of the unsubstituted hydrazones were evaluated from potentiometric and spectrophotometric data in dioxane-water mixtures. On the basis of the spectral analysis and PM3 semiempirical calculations, the structures of the formed complexes were proposed.