Mg5Ce crystallizes in the orthorhombic Amm2 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(5), and four equivalent Mg(4) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(1)Mg12 cuboctahedra, edges with four equivalent Mg(4)Ce2Mg10 cuboctahedra, edges with eight equivalent Ce(1)Ce2Mg10 cuboctahedra, faces with two equivalent Ce(1)Ce2Mg10 cuboctahedra, faces with four equivalent Mg(4)Ce2Mg10 cuboctahedra, faces with four equivalent Mg(1)Mg12 cuboctahedra, and faces with six equivalent Mg(5)Ce2Mg10 cuboctahedra. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), and four equivalent Ce(1) atoms. In the third Mg site, Mg(3) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), four equivalent Mg(5), and two equivalent Ce(1) atoms. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), four equivalent Mg(1), and two equivalent Ce(1) atoms to form MgCe2Mg10 cuboctahedra that share corners with six equivalent Mg(4)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(5)Ce2Mg10 cuboctahedra, corners with six equivalent Ce(1)Ce2Mg10 cuboctahedra, edges with three equivalent Mg(5)Ce2Mg10 cuboctahedra, edges with three equivalent Ce(1)Ce2Mg10 cuboctahedra, edges with four equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Mg(5)Ce2Mg10 cuboctahedra, faces with two equivalent Ce(1)Ce2Mg10 cuboctahedra, faces with four equivalent Mg(4)Ce2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Mg12 cuboctahedra. In the fifth Mg site, Mg(5) is bonded to two equivalent Mg(1), two equivalent Mg(4), two equivalent Mg(5), four equivalent Mg(3), and two equivalent Ce(1) atoms to form MgCe2Mg10 cuboctahedra that share corners with six equivalent Mg(4)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(5)Ce2Mg10 cuboctahedra, corners with six equivalent Ce(1)Ce2Mg10 cuboctahedra, edges with three equivalent Mg(4)Ce2Mg10 cuboctahedra, edges with three equivalent Ce(1)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(4)Ce2Mg10 cuboctahedra, faces with two equivalent Ce(1)Ce2Mg10 cuboctahedra, faces with four equivalent Mg(5)Ce2Mg10 cuboctahedra, and faces with six equivalent Mg(1)Mg12 cuboctahedra. Ce(1) is bonded to two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(5), four equivalent Mg(2), and two equivalent Ce(1) atoms to form CeCe2Mg10 cuboctahedra that share corners with six equivalent Mg(4)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(5)Ce2Mg10 cuboctahedra, corners with six equivalent Ce(1)Ce2Mg10 cuboctahedra, edges with three equivalent Mg(4)Ce2Mg10 cuboctahedra, edges with three equivalent Mg(5)Ce2Mg10 cuboctahedra, edges with eight equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Mg(4)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(5)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, and faces with four equivalent Ce(1)Ce2Mg10 cuboctahedra.
Mg5Ce crystallizes in the orthorhombic Amm2 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(5), and four equivalent Mg(4) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(1)Mg12 cuboctahedra, edges with four equivalent Mg(4)Ce2Mg10 cuboctahedra, edges with eight equivalent Ce(1)Ce2Mg10 cuboctahedra, faces with two equivalent Ce(1)Ce2Mg10 cuboctahedra, faces with four equivalent Mg(4)Ce2Mg10 cuboctahedra, faces with four equivalent Mg(1)Mg12 cuboctahedra, and faces with six equivalent Mg(5)Ce2Mg10 cuboctahedra. Both Mg(1)-Mg(1) bond lengths are 3.09 Å. Both Mg(1)-Mg(2) bond lengths are 3.19 Å. Both Mg(1)-Mg(3) bond lengths are 3.31 Å. Both Mg(1)-Mg(5) bond lengths are 3.22 Å. All Mg(1)-Mg(4) bond lengths are 3.20 Å. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), and four equivalent Ce(1) atoms. Both Mg(2)-Mg(2) bond lengths are 3.09 Å. Both Mg(2)-Mg(4) bond lengths are 3.19 Å. All Mg(2)-Ce(1) bond lengths are 3.29 Å. In the third Mg site, Mg(3) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), four equivalent Mg(5), and two equivalent Ce(1) atoms. Both Mg(3)-Mg(3) bond lengths are 3.09 Å. All Mg(3)-Mg(5) bond lengths are 3.23 Å. Both Mg(3)-Ce(1) bond lengths are 3.30 Å. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), four equivalent Mg(1), and two equivalent Ce(1) atoms to form MgCe2Mg10 cuboctahedra that share corners with six equivalent Mg(4)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(5)Ce2Mg10 cuboctahedra, corners with six equivalent Ce(1)Ce2Mg10 cuboctahedra, edges with three equivalent Mg(5)Ce2Mg10 cuboctahedra, edges with three equivalent Ce(1)Ce2Mg10 cuboctahedra, edges with four equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Mg(5)Ce2Mg10 cuboctahedra, faces with two equivalent Ce(1)Ce2Mg10 cuboctahedra, faces with four equivalent Mg(4)Ce2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Mg12 cuboctahedra. Both Mg(4)-Mg(4) bond lengths are 3.09 Å. Both Mg(4)-Mg(5) bond lengths are 3.24 Å. Both Mg(4)-Ce(1) bond lengths are 3.43 Å. In the fifth Mg site, Mg(5) is bonded to two equivalent Mg(1), two equivalent Mg(4), two equivalent Mg(5), four equivalent Mg(3), and two equivalent Ce(1) atoms to form MgCe2Mg10 cuboctahedra that share corners with six equivalent Mg(4)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(5)Ce2Mg10 cuboctahedra, corners with six equivalent Ce(1)Ce2Mg10 cuboctahedra, edges with three equivalent Mg(4)Ce2Mg10 cuboctahedra, edges with three equivalent Ce(1)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(4)Ce2Mg10 cuboctahedra, faces with two equivalent Ce(1)Ce2Mg10 cuboctahedra, faces with four equivalent Mg(5)Ce2Mg10 cuboctahedra, and faces with six equivalent Mg(1)Mg12 cuboctahedra. Both Mg(5)-Mg(5) bond lengths are 3.09 Å. Both Mg(5)-Ce(1) bond lengths are 3.43 Å. Ce(1) is bonded to two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(5), four equivalent Mg(2), and two equivalent Ce(1) atoms to form CeCe2Mg10 cuboctahedra that share corners with six equivalent Mg(4)Ce2Mg10 cuboctahedra, corners with six equivalent Mg(5)Ce2Mg10 cuboctahedra, corners with six equivalent Ce(1)Ce2Mg10 cuboctahedra, edges with three equivalent Mg(4)Ce2Mg10 cuboctahedra, edges with three equivalent Mg(5)Ce2Mg10 cuboctahedra, edges with eight equivalent Mg(1)Mg12 cuboctahedra, faces with two equivalent Mg(4)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(5)Ce2Mg10 cuboctahedra, faces with two equivalent Mg(1)Mg12 cuboctahedra, and faces with four equivalent Ce(1)Ce2Mg10 cuboctahedra. Both Ce(1)-Ce(1) bond lengths are 3.09 Å.