Extended Data Fig. 6: Synthesis of [K(crypt)][Lu(OAr*)3], 4.

Potassium reduction of Lu(OAr*)3 in the presence of 2.2.2-cryptand yields [K(crypt)][Lu(OAr*)3].
Potassium reduction of Lu(OAr*)3 in the presence of 2.2.2-cryptand yields [K(crypt)][Lu(OAr*)3].