Zirconium(III) chloride is an inorganic compound with formula ZrCl3. It is a blue-black solid that is highly sensitive to air.
The material was first claimed by Ruff and Wallstein who reduced zirconium tetrachloride with aluminium to give impure samples.[1] Subsequently, the problem with aluminium contamination was solved when it was prepared by reduction using zirconium metal:[2]
Zr + 3 ZrCl4 → 4 ZrCl3
When aluminium is used as the reducing agent with zirconium tetrachloride, a series of choloroaluminates are formed, for example [Zr(AlCl<sub>4</sub>)<sub>2</sub>(AlCl<sub>4</sub>)<sub>2</sub>] and Zr(AlCl4)3.[3]
Since the trihalides, such as zirconium trichloride, are comparatively nonvolatile, contamination can be avoided by using a gaseous reductant. For example, zirconium trichloride can be prepared by reduction of zirconium tetrachloride with hydrogen.[4]
ZrCl4 + ½ H2 → ZrCl3 + HCl
Some zirconium halides (ZrCl3, ZrBr3, and ZrI3) have structures similar to HfI3. They also have similar space group (P63/mcm) and hexagonal structure with 2 molecules in the cell. The magnetic susceptibility of zirconium trichloride suggests metal-metal interactions of the unpaired electron on each Zr(III) center. The magnetic moment of ZrCl3 (0.4 BM) indicates considerable overlap of metal orbitals.[5]