Chemistry - Can aluminium form blue-colored solution in liquid ammonia?

Solution 1:

The SE answers quoted in the comments provide a good broad answer but with respect to the question of aluminium – aluminium will form a blue solution in liquid ammonia following electrolytic reduction of $\ce{AlI3}$ in liquid ammonia according to J. Am. Chem. Soc. 1950, 72 (11), 5178–5180.

Europium and ytterbium have also been reported to dissolve in liquid ammonia in J. Phys. Chem. 1956, 60 (11), 1590–1591.

Solution 2:

Yes, aluminium forms a blue colored solution in liquid ammonia. Liquid ammonia will dissolve group 1 (alkali) metals and other electropositive metals such as calcium, strontium, barium, magnesium, aluminum, europium, and ytterbium. At low concentrations (ca. $\pu{0.06 mol/L}$), deep blue solutions are formed: these contain metal cations and solvated electrons. The solvated electrons are stable in liquid ammonia and form a complex: $\ce{[e^-(NH3)6]}$. For further details see Chemistry of the main group elements by Andrew R. Barron on openstax