For the materials with M(III) = Y (ref. ), Er (ref ), Yb (ref. ), a trigonal 𝑃3 ̅ 𝑚1 to orthorhombic 𝑃𝑛𝑚𝑎 phase transition has been observed upon Zr-substitution. This is rationalized by the reduction of the average transition metal radius by introducing the smaller Zr(IV)-ion (the Shannon radius of Zr is 0.72 Å in 6-fold coordination, compared to Y(0.90 Å), Er (0.89 Å) and Yb (0.87 Å)) . The 𝑃𝑛𝑚𝑎 phase can also be synthesized without Zrsubstitution, by synthesizing the material by co-melting of the reagents with small LiCl deficiency . For Li-3M(III)Cl6 with smaller M(III), such as In (0.80 Å) investigated in this report and Sc (0.75 Å), the structure crystallizes in monoclinic 𝐶2/𝑚 . The structure consists of a doubled LiCl unit cell with a small monoclinic distortion and part of the Li + replaced by