CeMg crystallizes in the monoclinic Cm space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), three equivalent Mg(3), one Ce(3), two equivalent Ce(1), and two equivalent Ce(2) atoms to form MgCe5Mg7 cuboctahedra that share corners with six equivalent Mg(1)Ce5Mg7 cuboctahedra, corners with six equivalent Mg(2)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with two equivalent Mg(3)Ce5Mg7 cuboctahedra, edges with three equivalent Mg(2)Ce6Mg6 cuboctahedra, edges with three equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with four equivalent Ce(3)Ce6Mg6 cuboctahedra, edges with six equivalent Ce(1)Ce7Mg5 cuboctahedra, faces with two equivalent Mg(1)Ce5Mg7 cuboctahedra, faces with three equivalent Mg(2)Ce6Mg6 cuboctahedra, faces with three equivalent Ce(1)Ce7Mg5 cuboctahedra, faces with three equivalent Ce(2)Ce7Mg5 cuboctahedra, faces with four equivalent Ce(3)Ce6Mg6 cuboctahedra, and faces with five equivalent Mg(3)Ce5Mg7 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), one Ce(1), two equivalent Ce(2), and three equivalent Ce(3) atoms to form MgCe6Mg6 cuboctahedra that share corners with six equivalent Mg(1)Ce5Mg7 cuboctahedra, corners with six equivalent Mg(2)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with two equivalent Ce(3)Ce6Mg6 cuboctahedra, edges with three equivalent Mg(1)Ce5Mg7 cuboctahedra, edges with three equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with four equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with six equivalent Mg(3)Ce5Mg7 cuboctahedra, faces with two equivalent Mg(2)Ce6Mg6 cuboctahedra, faces with three equivalent Mg(1)Ce5Mg7 cuboctahedra, faces with three equivalent Mg(3)Ce5Mg7 cuboctahedra, faces with three equivalent Ce(2)Ce7Mg5 cuboctahedra, faces with four equivalent Ce(1)Ce7Mg5 cuboctahedra, and faces with five equivalent Ce(3)Ce6Mg6 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Mg(2), two equivalent Mg(3), three equivalent Mg(1), one Ce(2), two equivalent Ce(1), and two equivalent Ce(3) atoms to form distorted MgCe5Mg7 cuboctahedra that share corners with six equivalent Mg(3)Ce5Mg7 cuboctahedra, corners with six equivalent Ce(3)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with two equivalent Mg(1)Ce5Mg7 cuboctahedra, edges with three equivalent Ce(3)Ce6Mg6 cuboctahedra, edges with three equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with four equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with six equivalent Mg(2)Ce6Mg6 cuboctahedra, faces with two equivalent Mg(3)Ce5Mg7 cuboctahedra, faces with three equivalent Mg(2)Ce6Mg6 cuboctahedra, faces with three equivalent Ce(3)Ce6Mg6 cuboctahedra, faces with three equivalent Ce(1)Ce7Mg5 cuboctahedra, faces with four equivalent Ce(2)Ce7Mg5 cuboctahedra, and faces with five equivalent Mg(1)Ce5Mg7 cuboctahedra. There are three inequivalent Ce sites. In the first Ce site, Ce(1) is bonded to one Mg(2), two equivalent Mg(1), two equivalent Mg(3), two equivalent Ce(1), two equivalent Ce(3), and three equivalent Ce(2) atoms to form distorted CeCe7Mg5 cuboctahedra that share corners with six equivalent Mg(3)Ce5Mg7 cuboctahedra, corners with six equivalent Ce(3)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with two equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with three equivalent Mg(3)Ce5Mg7 cuboctahedra, edges with three equivalent Ce(3)Ce6Mg6 cuboctahedra, edges with four equivalent Mg(2)Ce6Mg6 cuboctahedra, edges with six equivalent Mg(1)Ce5Mg7 cuboctahedra, faces with two equivalent Ce(1)Ce7Mg5 cuboctahedra, faces with three equivalent Mg(1)Ce5Mg7 cuboctahedra, faces with three equivalent Mg(3)Ce5Mg7 cuboctahedra, faces with three equivalent Ce(3)Ce6Mg6 cuboctahedra, faces with four equivalent Mg(2)Ce6Mg6 cuboctahedra, and faces with five equivalent Ce(2)Ce7Mg5 cuboctahedra. In the second Ce site, Ce(2) is bonded to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), two equivalent Ce(2), two equivalent Ce(3), and three equivalent Ce(1) atoms to form distorted CeCe7Mg5 cuboctahedra that share corners with six equivalent Mg(1)Ce5Mg7 cuboctahedra, corners with six equivalent Mg(2)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with two equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with three equivalent Mg(1)Ce5Mg7 cuboctahedra, edges with three equivalent Mg(2)Ce6Mg6 cuboctahedra, edges with four equivalent Mg(3)Ce5Mg7 cuboctahedra, edges with six equivalent Ce(3)Ce6Mg6 cuboctahedra, faces with two equivalent Ce(2)Ce7Mg5 cuboctahedra, faces with three equivalent Mg(1)Ce5Mg7 cuboctahedra, faces with three equivalent Mg(2)Ce6Mg6 cuboctahedra, faces with three equivalent Ce(3)Ce6Mg6 cuboctahedra, faces with four equivalent Mg(3)Ce5Mg7 cuboctahedra, and faces with five equivalent Ce(1)Ce7Mg5 cuboctahedra. In the third Ce site, Ce(3) is bonded to one Mg(1), two equivalent Mg(3), three equivalent Mg(2), two equivalent Ce(1), two equivalent Ce(2), and two equivalent Ce(3) atoms to form CeCe6Mg6 cuboctahedra that share corners with six equivalent Mg(3)Ce5Mg7 cuboctahedra, corners with six equivalent Ce(3)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with two equivalent Mg(2)Ce6Mg6 cuboctahedra, edges with three equivalent Mg(3)Ce5Mg7 cuboctahedra, edges with three equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with four equivalent Mg(1)Ce5Mg7 cuboctahedra, edges with six equivalent Ce(2)Ce7Mg5 cuboctahedra, faces with two equivalent Ce(3)Ce6Mg6 cuboctahedra, faces with three equivalent Mg(3)Ce5Mg7 cuboctahedra, faces with three equivalent Ce(1)Ce7Mg5 cuboctahedra, faces with three equivalent Ce(2)Ce7Mg5 cuboctahedra, faces with four equivalent Mg(1)Ce5Mg7 cuboctahedra, and faces with five equivalent Mg(2)Ce6Mg6 cuboctahedra.
CeMg crystallizes in the monoclinic Cm space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), three equivalent Mg(3), one Ce(3), two equivalent Ce(1), and two equivalent Ce(2) atoms to form MgCe5Mg7 cuboctahedra that share corners with six equivalent Mg(1)Ce5Mg7 cuboctahedra, corners with six equivalent Mg(2)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with two equivalent Mg(3)Ce5Mg7 cuboctahedra, edges with three equivalent Mg(2)Ce6Mg6 cuboctahedra, edges with three equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with four equivalent Ce(3)Ce6Mg6 cuboctahedra, edges with six equivalent Ce(1)Ce7Mg5 cuboctahedra, faces with two equivalent Mg(1)Ce5Mg7 cuboctahedra, faces with three equivalent Mg(2)Ce6Mg6 cuboctahedra, faces with three equivalent Ce(1)Ce7Mg5 cuboctahedra, faces with three equivalent Ce(2)Ce7Mg5 cuboctahedra, faces with four equivalent Ce(3)Ce6Mg6 cuboctahedra, and faces with five equivalent Mg(3)Ce5Mg7 cuboctahedra. Both Mg(1)-Mg(1) bond lengths are 3.14 Å. Both Mg(1)-Mg(2) bond lengths are 3.19 Å. There are two shorter (3.29 Å) and one longer (3.42 Å) Mg(1)-Mg(3) bond length. The Mg(1)-Ce(3) bond length is 3.52 Å. Both Mg(1)-Ce(1) bond lengths are 3.55 Å. Both Mg(1)-Ce(2) bond lengths are 3.57 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), one Ce(1), two equivalent Ce(2), and three equivalent Ce(3) atoms to form MgCe6Mg6 cuboctahedra that share corners with six equivalent Mg(1)Ce5Mg7 cuboctahedra, corners with six equivalent Mg(2)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with two equivalent Ce(3)Ce6Mg6 cuboctahedra, edges with three equivalent Mg(1)Ce5Mg7 cuboctahedra, edges with three equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with four equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with six equivalent Mg(3)Ce5Mg7 cuboctahedra, faces with two equivalent Mg(2)Ce6Mg6 cuboctahedra, faces with three equivalent Mg(1)Ce5Mg7 cuboctahedra, faces with three equivalent Mg(3)Ce5Mg7 cuboctahedra, faces with three equivalent Ce(2)Ce7Mg5 cuboctahedra, faces with four equivalent Ce(1)Ce7Mg5 cuboctahedra, and faces with five equivalent Ce(3)Ce6Mg6 cuboctahedra. Both Mg(2)-Mg(2) bond lengths are 3.14 Å. Both Mg(2)-Mg(3) bond lengths are 3.13 Å. The Mg(2)-Ce(1) bond length is 3.30 Å. Both Mg(2)-Ce(2) bond lengths are 3.40 Å. There are two shorter (3.45 Å) and one longer (3.46 Å) Mg(2)-Ce(3) bond length. In the third Mg site, Mg(3) is bonded to two equivalent Mg(2), two equivalent Mg(3), three equivalent Mg(1), one Ce(2), two equivalent Ce(1), and two equivalent Ce(3) atoms to form distorted MgCe5Mg7 cuboctahedra that share corners with six equivalent Mg(3)Ce5Mg7 cuboctahedra, corners with six equivalent Ce(3)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with two equivalent Mg(1)Ce5Mg7 cuboctahedra, edges with three equivalent Ce(3)Ce6Mg6 cuboctahedra, edges with three equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with four equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with six equivalent Mg(2)Ce6Mg6 cuboctahedra, faces with two equivalent Mg(3)Ce5Mg7 cuboctahedra, faces with three equivalent Mg(2)Ce6Mg6 cuboctahedra, faces with three equivalent Ce(3)Ce6Mg6 cuboctahedra, faces with three equivalent Ce(1)Ce7Mg5 cuboctahedra, faces with four equivalent Ce(2)Ce7Mg5 cuboctahedra, and faces with five equivalent Mg(1)Ce5Mg7 cuboctahedra. Both Mg(3)-Mg(3) bond lengths are 3.14 Å. The Mg(3)-Ce(2) bond length is 3.39 Å. Both Mg(3)-Ce(1) bond lengths are 3.47 Å. Both Mg(3)-Ce(3) bond lengths are 3.59 Å. There are three inequivalent Ce sites. In the first Ce site, Ce(1) is bonded to one Mg(2), two equivalent Mg(1), two equivalent Mg(3), two equivalent Ce(1), two equivalent Ce(3), and three equivalent Ce(2) atoms to form distorted CeCe7Mg5 cuboctahedra that share corners with six equivalent Mg(3)Ce5Mg7 cuboctahedra, corners with six equivalent Ce(3)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with two equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with three equivalent Mg(3)Ce5Mg7 cuboctahedra, edges with three equivalent Ce(3)Ce6Mg6 cuboctahedra, edges with four equivalent Mg(2)Ce6Mg6 cuboctahedra, edges with six equivalent Mg(1)Ce5Mg7 cuboctahedra, faces with two equivalent Ce(1)Ce7Mg5 cuboctahedra, faces with three equivalent Mg(1)Ce5Mg7 cuboctahedra, faces with three equivalent Mg(3)Ce5Mg7 cuboctahedra, faces with three equivalent Ce(3)Ce6Mg6 cuboctahedra, faces with four equivalent Mg(2)Ce6Mg6 cuboctahedra, and faces with five equivalent Ce(2)Ce7Mg5 cuboctahedra. Both Ce(1)-Ce(1) bond lengths are 3.14 Å. Both Ce(1)-Ce(3) bond lengths are 3.12 Å. There are two shorter (3.08 Å) and one longer (3.65 Å) Ce(1)-Ce(2) bond length. In the second Ce site, Ce(2) is bonded to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), two equivalent Ce(2), two equivalent Ce(3), and three equivalent Ce(1) atoms to form distorted CeCe7Mg5 cuboctahedra that share corners with six equivalent Mg(1)Ce5Mg7 cuboctahedra, corners with six equivalent Mg(2)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(2)Ce7Mg5 cuboctahedra, edges with two equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with three equivalent Mg(1)Ce5Mg7 cuboctahedra, edges with three equivalent Mg(2)Ce6Mg6 cuboctahedra, edges with four equivalent Mg(3)Ce5Mg7 cuboctahedra, edges with six equivalent Ce(3)Ce6Mg6 cuboctahedra, faces with two equivalent Ce(2)Ce7Mg5 cuboctahedra, faces with three equivalent Mg(1)Ce5Mg7 cuboctahedra, faces with three equivalent Mg(2)Ce6Mg6 cuboctahedra, faces with three equivalent Ce(3)Ce6Mg6 cuboctahedra, faces with four equivalent Mg(3)Ce5Mg7 cuboctahedra, and faces with five equivalent Ce(1)Ce7Mg5 cuboctahedra. Both Ce(2)-Ce(2) bond lengths are 3.14 Å. Both Ce(2)-Ce(3) bond lengths are 3.09 Å. In the third Ce site, Ce(3) is bonded to one Mg(1), two equivalent Mg(3), three equivalent Mg(2), two equivalent Ce(1), two equivalent Ce(2), and two equivalent Ce(3) atoms to form CeCe6Mg6 cuboctahedra that share corners with six equivalent Mg(3)Ce5Mg7 cuboctahedra, corners with six equivalent Ce(3)Ce6Mg6 cuboctahedra, corners with six equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with two equivalent Mg(2)Ce6Mg6 cuboctahedra, edges with three equivalent Mg(3)Ce5Mg7 cuboctahedra, edges with three equivalent Ce(1)Ce7Mg5 cuboctahedra, edges with four equivalent Mg(1)Ce5Mg7 cuboctahedra, edges with six equivalent Ce(2)Ce7Mg5 cuboctahedra, faces with two equivalent Ce(3)Ce6Mg6 cuboctahedra, faces with three equivalent Mg(3)Ce5Mg7 cuboctahedra, faces with three equivalent Ce(1)Ce7Mg5 cuboctahedra, faces with three equivalent Ce(2)Ce7Mg5 cuboctahedra, faces with four equivalent Mg(1)Ce5Mg7 cuboctahedra, and faces with five equivalent Mg(2)Ce6Mg6 cuboctahedra. Both Ce(3)-Ce(3) bond lengths are 3.14 Å.