The crystal structure of aluminium chloride

Aluminium chloride crystallizes in an ionic layer lattice. The dimensions of the monoclinic cell and the position of the chlorine atoms, given by Ketelaar in a previous investigation, are confirmed. The position of the Al‐atoms is different; instead of the ionic structure described in this paper, Ketelaar found a molecular lattice of “octahedral” molecules, fig. 1a. The structure appears to be in conflict with the result of the Raman investigation of solid AlCl 3 by Gerding and Smit , which suggested a packing of “tetrahedral” molecules, fig. 1b.