The Raman spectra of the compounds NaCl. ALCL3 and NOCl. ALCL3

The Raman frequency shifts and the depolarization ratio of the Raman lines have been determined for the compounds NaCl. AlCl3 and NOCl. AlCl3 (in the last case with qualitative polarization measurements only). The preparation of pure NOCl. AlCl3 is described in extenso. The properties of the compound finally obtained are different from those given in the literature. NaCl. AlCl3, has to be considered as Na+AlCl4−, and NOCl. AlCl3 as NO+AlCl4−. There is a perceptible interaction between nitrosyl and the chlorines of AlCl4− in the last compound. The properties of NOCl. AlCl3 are intermediate between those for a pure heteropolar compound (NO+AlCl4−) and a pure molecular compound NOCl. AlCl3, being more alike those of the heteropolar form. Force constants have been calculated for AlCl4;−, making use of the Lechner formulae and of those for a Urey‐Bradley field and also of those for the orbital valence force field of Heath and Linnett.