Chromium(III) chloride is a Lewis acid, classified as "hard" according to the Hard-Soft Acid-Base theory. However it is also a chloro complex which is quite inert to substitution, so in fact it is ordinarily quite unreactive. The low reactivity of the d3 Cr3+ ion can be explained using crystal field theory. One way of opening CrCl3 up to substitution in solution is to reduce even a trace amount to CrCl2, for example using zinc in hydrochloric acid. This chromium(II) compound undergoes substi ...
Chromium(III) chloride is used as the source of chromium for many inorganic compounds of chromium, for example dibenzenechromium(0), an analogue of ferrocene:
A significant use of CrCl3 in organic synthesis is for the in situ preparation of chromium(II) chloride, a popular reagent for (A) reduction of alkyl halides and for (B) the synthesis of (E)-alkenyl halides. The reaction is usually performed using two moles of CrCl3 per mole of lithium aluminium hydride, although if aqueous acidic conditions are appropriate zinc and ...
Anhydrous chromium(III) chloride may be prepared from chromium metal and chlorine directly, or indirectly using chromium(III) oxide with carbon and chlorine at 800 °C[4]:
Cr2O3(s) + 3 C(s) + 3 Cl2(g) → 2 CrCl3(s) + 3 CO(g)
It may also be prepared from the hexahydrate, by heating with thionyl chloride which reacts with the water of hydration.
The hydrated chloride may b ...
