“…More recently, the crystalline structure of the molecular complex formed by N,N,N',N'-tetramethyl-p-phenylenediamine and sulphur dioxide was determined. 7 In contrasting with the limited knowledge of the structure of such compounds, some of them have found interesting applications as polymerization catalysts' and some aromatic amines proved to be very efficient in the removal of sulphur dioxide from effluent gasesg We have been involved in the vibrational spectroscopy of sulphur dioxide molecular complexes'091' and decided to extend our studies, investigating the interaction of SO, with aniline (ANI), N-methylaniline (NMA), N,N-dimethylaniline (DMA), N , Ndiet hylaniline (DEA), p-phenylenediamine (PPD) and ,V,N,N',N'-tetramethyl-p-phenylenediamine (TPD) by means of Raman and infrared spectroscopy and, in favourable cases, to explore the Raman pre-resonance effect, since in all cases an intense absorption band is present in the near-UV region. ANI, NMA, DMA and DEA were used after distillation of the commercial products over zinc powder.…”