In this issue, we describe the synthesis and chemical analysis of new trichloride compounds : tetraphenylphosphonium trichloride, (C6H5)4PCl3and pyridinium trichloride, C5H6NCl3. Those are vibrationaly studied and compared with tetrabutylammonium trichloride and tetraphenylarsonium trichloride. Raman spectroscopy spectras show an intense stretching band ν1at 270 cm−1. Its straightforward intensity is explained by the preresonance spectra of the trichloride ion.