Transmethylation of 2-(methylthio)benzothiazole on silver sols: a SERS investigation

Discrepancies between the SERS and the normal Raman spectra of 2-(methylthio)benzothiazole (MTBT) led to an extension of the SERS study to include an investigation of the reactivity of this molecule on a silver surface. Experimental evidence indicates a surface reaction of MTBT on silver sot. In particular, it undergoes an intramolecular transmethylation, rearranging to 3-methylbenzothiazoline-2-thione. Experimental data suggest that this transmethylation takes place only because of the presence of the silver surface, which acts as a catalyst. In contrast, the hypothesis of a reaction photo-induced by the silver surface seems very unlikely. 3-Methylbenzothiazoline-2-thione adsorbs on the silver surface via the lone pairs of the exocyclic sulphur atom and, to some extent, also via the pi-system of the benzene ring. The molecular orientation is inclined with respect to the metal surface. Copyright (C) 2002 John Wiley Sons, Ltd.