CeMg2 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), four equivalent Mg(2), and six equivalent Ce(1) atoms to form MgCe6Mg6 cuboctahedra that share corners with six equivalent Mg(2)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(1)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(1)Ce4Mg8 cuboctahedra, edges with three equivalent Mg(2)Ce2Mg10 cuboctahedra, edges with seven equivalent Ce(1)Ce4Mg8 cuboctahedra, edges with eight equivalent Mg(1)Ce6Mg6 cuboctahedra, faces with six equivalent Mg(1)Ce6Mg6 cuboctahedra, faces with six equivalent Ce(1)Ce4Mg8 cuboctahedra, and faces with eight equivalent Mg(2)Ce2Mg10 cuboctahedra. In the second Mg site, Mg(2) is bonded to four equivalent Mg(1), six equivalent Mg(2), and two equivalent Ce(1) atoms to form MgCe2Mg10 cuboctahedra that share corners with six equivalent Mg(2)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(1)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(1)Ce4Mg8 cuboctahedra, edges with three equivalent Mg(1)Ce6Mg6 cuboctahedra, edges with four equivalent Mg(2)Ce2Mg10 cuboctahedra, edges with eleven equivalent Ce(1)Ce4Mg8 cuboctahedra, faces with four equivalent Ce(1)Ce4Mg8 cuboctahedra, faces with eight equivalent Mg(2)Ce2Mg10 cuboctahedra, and faces with eight equivalent Mg(1)Ce6Mg6 cuboctahedra. Ce(1) is bonded to two equivalent Mg(2), six equivalent Mg(1), and four equivalent Ce(1) atoms to form CeCe4Mg8 cuboctahedra that share corners with six equivalent Mg(2)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(1)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(1)Ce4Mg8 cuboctahedra, edges with seven equivalent Mg(1)Ce6Mg6 cuboctahedra, edges with eleven equivalent Mg(2)Ce2Mg10 cuboctahedra, faces with four equivalent Mg(2)Ce2Mg10 cuboctahedra, faces with six equivalent Mg(1)Ce6Mg6 cuboctahedra, and faces with ten equivalent Ce(1)Ce4Mg8 cuboctahedra.
CeMg2 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), four equivalent Mg(2), and six equivalent Ce(1) atoms to form MgCe6Mg6 cuboctahedra that share corners with six equivalent Mg(2)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(1)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(1)Ce4Mg8 cuboctahedra, edges with three equivalent Mg(2)Ce2Mg10 cuboctahedra, edges with seven equivalent Ce(1)Ce4Mg8 cuboctahedra, edges with eight equivalent Mg(1)Ce6Mg6 cuboctahedra, faces with six equivalent Mg(1)Ce6Mg6 cuboctahedra, faces with six equivalent Ce(1)Ce4Mg8 cuboctahedra, and faces with eight equivalent Mg(2)Ce2Mg10 cuboctahedra. Both Mg(1)-Mg(1) bond lengths are 3.10 Å. There are two shorter (3.05 Å) and two longer (3.22 Å) Mg(1)-Mg(2) bond lengths. There are two shorter (3.32 Å) and four longer (3.42 Å) Mg(1)-Ce(1) bond lengths. In the second Mg site, Mg(2) is bonded to four equivalent Mg(1), six equivalent Mg(2), and two equivalent Ce(1) atoms to form MgCe2Mg10 cuboctahedra that share corners with six equivalent Mg(2)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(1)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(1)Ce4Mg8 cuboctahedra, edges with three equivalent Mg(1)Ce6Mg6 cuboctahedra, edges with four equivalent Mg(2)Ce2Mg10 cuboctahedra, edges with eleven equivalent Ce(1)Ce4Mg8 cuboctahedra, faces with four equivalent Ce(1)Ce4Mg8 cuboctahedra, faces with eight equivalent Mg(2)Ce2Mg10 cuboctahedra, and faces with eight equivalent Mg(1)Ce6Mg6 cuboctahedra. There are two shorter (3.10 Å) and four longer (3.24 Å) Mg(2)-Mg(2) bond lengths. Both Mg(2)-Ce(1) bond lengths are 3.61 Å. Ce(1) is bonded to two equivalent Mg(2), six equivalent Mg(1), and four equivalent Ce(1) atoms to form CeCe4Mg8 cuboctahedra that share corners with six equivalent Mg(2)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(1)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(1)Ce4Mg8 cuboctahedra, edges with seven equivalent Mg(1)Ce6Mg6 cuboctahedra, edges with eleven equivalent Mg(2)Ce2Mg10 cuboctahedra, faces with four equivalent Mg(2)Ce2Mg10 cuboctahedra, faces with six equivalent Mg(1)Ce6Mg6 cuboctahedra, and faces with ten equivalent Ce(1)Ce4Mg8 cuboctahedra. There are two shorter (2.89 Å) and two longer (3.10 Å) Ce(1)-Ce(1) bond lengths.