Heterocyclic compounds used as corrosion inhibitors: correlation between C-13 and H-1 NMR spectroscopy and inhibition efficiency

Among the corrosion inhibitors of copper, four aromatic heterocyclic compou nds, their corresponding sodium salts and Cu(I) complexes are studied using C-13 NMR and H-1 NMR spectroscopies in DMSO d(6). With regard to the spect ra of the neutral molecules, the spectra of the sodium salts are always shi fted upfield. By contrast, the spectra of the copper complexes shift either downfield or slightly upheld, showing that two different types of bindings with Cu(I) are involved. The correlation between the chemical shift of the Cu(I)-organic compound and its inhibition efficiency is discussed. (C) 199 8 Published by Elsevier Science Ltd. All rights reserved.