AbstractThe Raman spectra (inclusive of polarization measurements) of liquid and solid AlCl3. NH3have been taken.An assignment of frequency shifts to vibrations of AlCl3. NH3(symmetry C3v) ‐ somewhat different from that assumed byGoubeauandSiebert‐ has been given. Force constants have been calculated from these frequencies withWagner's formulae.To the symmetrical stretching vibration of N‐H in Cl3Al. NH3a frequency has been assigned by us (liquid 3247 cm−1; solid 3259 cm−1), which is higher than the one assumed byGoubeauandSiebert(2900 cm−1). Our value shows a rather small difference from the corresponding one