Erbium(III) chloride

Erbium(III) chloride is a violet solid used for the preparation of erbium metal. It is also found as a pink crystalline hexahydrate, CAS number [10025-75-9]. It has the interesting property that the pink colour is much more intense under the light from a fluorescent lamp, as may be seen from the picture.

Anhydrous erbium(III) chloride is formed from the hexahydrate by heating under a strongly chlorinating atmosphere, such as chlorine or hydrogen chloride; otherwise erbium oxide chloride, ErOCl, is formed.

Structural data
Erbium chloride forms crystals of the AlCl3 type, with monoclinic crystals and the point group C2/m.

Erbium(III) chloride hexahydrate also forms monoclinic crystals with the point group of P2/n (P2/c) - C42h. The erbium is octa-coordinated to form [Er(H2O)6Cl2]+ ions with the isolated Cl&minus; completing the structure.

Optical properties
Erbium(III) chloride solutions show a negative nonlinear absorption effect.

Catalytic properties
Erbium(III) chloride is a powerful catalyst for the acylation of alcohols and phenols, and can be easily recycled and reused without significant loss of activity.