Raman and DFT study of the vibrational properties of some para-substituted benzohydroxamic acids:: towards an interpretation of SER spectra

The vibrational properties of p-chloro-, p-methoxy- and p-nitrobenzohydroxamic acids (BHA) and of the unsubstituted BHA were investigated and the spectra were assigned. The assignment was made on the basis of the experimental information available about the Raman peaks of mono- and disubstituted benzenes and the procedure was greatly facilitated by the data obtained from high-level DFT quantum-chemical calculations. In order to support an intended assignment of the SER spectra of BHA on copper, the molecular electrostatic maps and Fukui functions were derived. from ab initio calculations. Both quantum-chemical descriptors were shown to provide similar information about the possible BHA molecule-copper surface interaction sites. Copyright (C) 2003 John Wiley Sons, Ltd.