Mg3In crystallizes in the trigonal R-3m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 2-coordinate geometry to two equivalent Mg(2), one In(1), and one In(2) atom. In the second Mg site, Mg(2) is bonded in a 9-coordinate geometry to two equivalent Mg(1), four equivalent Mg(2), one In(2), and two equivalent In(1) atoms. There are two inequivalent In sites. In the first In site, In(1) is bonded in a 10-coordinate geometry to three equivalent Mg(1), six equivalent Mg(2), and one In(2) atom. In the second In site, In(2) is bonded in a 7-coordinate geometry to three equivalent Mg(1), three equivalent Mg(2), and one In(1) atom.
Mg3In crystallizes in the trigonal R-3m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 2-coordinate geometry to two equivalent Mg(2), one In(1), and one In(2) atom. Both Mg(1)-Mg(2) bond lengths are 3.10 Å. The Mg(1)-In(1) bond length is 3.08 Å. The Mg(1)-In(2) bond length is 2.99 Å. In the second Mg site, Mg(2) is bonded in a 9-coordinate geometry to two equivalent Mg(1), four equivalent Mg(2), one In(2), and two equivalent In(1) atoms. There are two shorter (3.18 Å) and two longer (3.19 Å) Mg(2)-Mg(2) bond lengths. The Mg(2)-In(2) bond length is 3.20 Å. There is one shorter (3.07 Å) and one longer (3.47 Å) Mg(2)-In(1) bond length. There are two inequivalent In sites. In the first In site, In(1) is bonded in a 10-coordinate geometry to three equivalent Mg(1), six equivalent Mg(2), and one In(2) atom. The In(1)-In(2) bond length is 2.92 Å. In the second In site, In(2) is bonded in a 7-coordinate geometry to three equivalent Mg(1), three equivalent Mg(2), and one In(1) atom.