Mg3Ce crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 10-coordinate geometry to two equivalent Mg(1), four equivalent Mg(2), and four equivalent Ce(1) atoms. In the second Mg site, Mg(2) is bonded in a 11-coordinate geometry to two equivalent Mg(1), six equivalent Mg(2), and three equivalent Ce(1) atoms. Ce(1) is bonded to four equivalent Mg(1), six equivalent Mg(2), and two equivalent Ce(1) atoms to form a mixture of edge, face, and corner-sharing CeCe2Mg10 cuboctahedra.
Mg3Ce crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 10-coordinate geometry to two equivalent Mg(1), four equivalent Mg(2), and four equivalent Ce(1) atoms. Both Mg(1)-Mg(1) bond lengths are 3.18 Å. All Mg(1)-Mg(2) bond lengths are 3.37 Å. There are two shorter (3.38 Å) and two longer (3.42 Å) Mg(1)-Ce(1) bond lengths. In the second Mg site, Mg(2) is bonded in a 11-coordinate geometry to two equivalent Mg(1), six equivalent Mg(2), and three equivalent Ce(1) atoms. There are two shorter (3.18 Å) and four longer (3.40 Å) Mg(2)-Mg(2) bond lengths. There is one shorter (3.46 Å) and two longer (3.48 Å) Mg(2)-Ce(1) bond lengths. Ce(1) is bonded to four equivalent Mg(1), six equivalent Mg(2), and two equivalent Ce(1) atoms to form a mixture of edge, face, and corner-sharing CeCe2Mg10 cuboctahedra. Both Ce(1)-Ce(1) bond lengths are 3.18 Å.