 Gallium trichloride

Gallium trichloride is $\mathrm{GaC}{\mathrm{l}}_3$, a gallium(III) halide and Lewis acid. Its electron-pair-accepting behavior allows it to form adducts with donor molecules.

It can activate suitable substrates by coordination. Its molecular association and coordination environment depend on phase and solvent, so the simple formula does not require isolated three-coordinate molecules under every condition.