Study of charge transfer complexes of salicylideneanilines and its substituents with pr (fod) 3 in cyclohexane by U. V. spectroscopy

Salicylidene aniline and its substituents form 1:1 charge transfer complexes with the lanthanide shift reagent Pr(fod)3 in cyclohexane indicated by the observation of a new band in their U.V. spectra located at longer wavelength (λmax = 430 nm) and with its low extinction coefficient. The colourless solutions of Schiff’s-bases were changed to yellow on complexation with Pr(fod)3. Equilibrium constant values (K) for the complexes were calculated by applying Benesi-Hildebrand equation at different temperatures, and the thermodynamic parameters ΔH, ΔS and ΔG were obtained. Negative values of ΔG indicates that the complexation occurs spontaneously. Application of Hammet equation on K values for the para substituents show straight line with negative slope indicating that the electron donating groups enhances the reaction of complexation