SPECTROSCOPIC AND THEORETICAL-STUDY OF AROMATIC ALPHA-HYDROXY HYDRAZONES AND THEIR COPPER(II) COMPLEXES IN DIOXANE-WATER MIXTURES

Two aromatic a-hydroxy hydrazones, N-phenyl-N' (2-hydroxy-1-phenylmeth ylene hydrazine) and N-phenyl-N' (2-hydroxy-1-naphthylmethylene hydraz ine), and their copper(II) complexes have been studied in both 30% and 70% dioxane-water (v/v) systems. Structural analysis of the anionic f orms of the free compounds has been performed using C-13 NMR and elect ronic absorption spectroscopies and semiempirical NIO calculations. Th e equilibrium constants for the deprotonation reactions of the hydrazo nes and for their coordination with Cu(II) ion were studied by spectro photometric titration. Coordination binding sites and stereochemistry of the chelates were inferred from NMR spectroscopy. (C) 1998 Elsevier Science Ltd. All rights reserved.