MgCe3 is beta-derived structured and crystallizes in the orthorhombic Pmm2 space group. Mg(1) is bonded to two equivalent Mg(1), two equivalent Ce(1), four equivalent Ce(2), and four equivalent Ce(3) atoms to form MgCe10Mg2 cuboctahedra that share corners with eight equivalent Ce(3)Ce8Mg4 cuboctahedra, corners with ten equivalent Mg(1)Ce10Mg2 cuboctahedra, edges with two equivalent Mg(1)Ce10Mg2 cuboctahedra, edges with four equivalent Ce(1)Ce10Mg2 cuboctahedra, edges with four equivalent Ce(3)Ce8Mg4 cuboctahedra, edges with eight equivalent Ce(2)Ce8Mg4 cuboctahedra, faces with four equivalent Mg(1)Ce10Mg2 cuboctahedra, faces with four equivalent Ce(2)Ce8Mg4 cuboctahedra, faces with four equivalent Ce(3)Ce8Mg4 cuboctahedra, and faces with eight equivalent Ce(1)Ce10Mg2 cuboctahedra. There are three inequivalent Ce sites. In the first Ce site, Ce(1) is bonded to two equivalent Mg(1), two equivalent Ce(1), four equivalent Ce(2), and four equivalent Ce(3) atoms to form CeCe10Mg2 cuboctahedra that share corners with eight equivalent Ce(2)Ce8Mg4 cuboctahedra, corners with ten equivalent Ce(1)Ce10Mg2 cuboctahedra, edges with two equivalent Ce(1)Ce10Mg2 cuboctahedra, edges with four equivalent Mg(1)Ce10Mg2 cuboctahedra, edges with four equivalent Ce(2)Ce8Mg4 cuboctahedra, edges with eight equivalent Ce(3)Ce8Mg4 cuboctahedra, faces with four equivalent Ce(1)Ce10Mg2 cuboctahedra, faces with four equivalent Ce(2)Ce8Mg4 cuboctahedra, faces with four equivalent Ce(3)Ce8Mg4 cuboctahedra, and faces with eight equivalent Mg(1)Ce10Mg2 cuboctahedra. In the second Ce site, Ce(2) is bonded to four equivalent Mg(1), two equivalent Ce(2), two equivalent Ce(3), and four equivalent Ce(1) atoms to form CeCe8Mg4 cuboctahedra that share corners with eight equivalent Ce(1)Ce10Mg2 cuboctahedra, corners with ten equivalent Ce(2)Ce8Mg4 cuboctahedra, edges with two equivalent Ce(2)Ce8Mg4 cuboctahedra, edges with four equivalent Ce(1)Ce10Mg2 cuboctahedra, edges with four equivalent Ce(3)Ce8Mg4 cuboctahedra, edges with eight equivalent Mg(1)Ce10Mg2 cuboctahedra, faces with four equivalent Mg(1)Ce10Mg2 cuboctahedra, faces with four equivalent Ce(1)Ce10Mg2 cuboctahedra, faces with four equivalent Ce(2)Ce8Mg4 cuboctahedra, and faces with eight equivalent Ce(3)Ce8Mg4 cuboctahedra. In the third Ce site, Ce(3) is bonded to four equivalent Mg(1), two equivalent Ce(2), two equivalent Ce(3), and four equivalent Ce(1) atoms to form CeCe8Mg4 cuboctahedra that share corners with eight equivalent Mg(1)Ce10Mg2 cuboctahedra, corners with ten equivalent Ce(3)Ce8Mg4 cuboctahedra, edges with two equivalent Ce(3)Ce8Mg4 cuboctahedra, edges with four equivalent Mg(1)Ce10Mg2 cuboctahedra, edges with four equivalent Ce(2)Ce8Mg4 cuboctahedra, edges with eight equivalent Ce(1)Ce10Mg2 cuboctahedra, faces with four equivalent Mg(1)Ce10Mg2 cuboctahedra, faces with four equivalent Ce(1)Ce10Mg2 cuboctahedra, faces with four equivalent Ce(3)Ce8Mg4 cuboctahedra, and faces with eight equivalent Ce(2)Ce8Mg4 cuboctahedra.
MgCe3 is beta-derived structured and crystallizes in the orthorhombic Pmm2 space group. Mg(1) is bonded to two equivalent Mg(1), two equivalent Ce(1), four equivalent Ce(2), and four equivalent Ce(3) atoms to form MgCe10Mg2 cuboctahedra that share corners with eight equivalent Ce(3)Ce8Mg4 cuboctahedra, corners with ten equivalent Mg(1)Ce10Mg2 cuboctahedra, edges with two equivalent Mg(1)Ce10Mg2 cuboctahedra, edges with four equivalent Ce(1)Ce10Mg2 cuboctahedra, edges with four equivalent Ce(3)Ce8Mg4 cuboctahedra, edges with eight equivalent Ce(2)Ce8Mg4 cuboctahedra, faces with four equivalent Mg(1)Ce10Mg2 cuboctahedra, faces with four equivalent Ce(2)Ce8Mg4 cuboctahedra, faces with four equivalent Ce(3)Ce8Mg4 cuboctahedra, and faces with eight equivalent Ce(1)Ce10Mg2 cuboctahedra. Both Mg(1)-Mg(1) bond lengths are 3.25 Å. Both Mg(1)-Ce(1) bond lengths are 3.38 Å. All Mg(1)-Ce(2) bond lengths are 3.33 Å. There are two shorter (3.31 Å) and two longer (3.47 Å) Mg(1)-Ce(3) bond lengths. There are three inequivalent Ce sites. In the first Ce site, Ce(1) is bonded to two equivalent Mg(1), two equivalent Ce(1), four equivalent Ce(2), and four equivalent Ce(3) atoms to form CeCe10Mg2 cuboctahedra that share corners with eight equivalent Ce(2)Ce8Mg4 cuboctahedra, corners with ten equivalent Ce(1)Ce10Mg2 cuboctahedra, edges with two equivalent Ce(1)Ce10Mg2 cuboctahedra, edges with four equivalent Mg(1)Ce10Mg2 cuboctahedra, edges with four equivalent Ce(2)Ce8Mg4 cuboctahedra, edges with eight equivalent Ce(3)Ce8Mg4 cuboctahedra, faces with four equivalent Ce(1)Ce10Mg2 cuboctahedra, faces with four equivalent Ce(2)Ce8Mg4 cuboctahedra, faces with four equivalent Ce(3)Ce8Mg4 cuboctahedra, and faces with eight equivalent Mg(1)Ce10Mg2 cuboctahedra. Both Ce(1)-Ce(1) bond lengths are 3.25 Å. There are two shorter (3.33 Å) and two longer (3.44 Å) Ce(1)-Ce(2) bond lengths. All Ce(1)-Ce(3) bond lengths are 3.32 Å. In the second Ce site, Ce(2) is bonded to four equivalent Mg(1), two equivalent Ce(2), two equivalent Ce(3), and four equivalent Ce(1) atoms to form CeCe8Mg4 cuboctahedra that share corners with eight equivalent Ce(1)Ce10Mg2 cuboctahedra, corners with ten equivalent Ce(2)Ce8Mg4 cuboctahedra, edges with two equivalent Ce(2)Ce8Mg4 cuboctahedra, edges with four equivalent Ce(1)Ce10Mg2 cuboctahedra, edges with four equivalent Ce(3)Ce8Mg4 cuboctahedra, edges with eight equivalent Mg(1)Ce10Mg2 cuboctahedra, faces with four equivalent Mg(1)Ce10Mg2 cuboctahedra, faces with four equivalent Ce(1)Ce10Mg2 cuboctahedra, faces with four equivalent Ce(2)Ce8Mg4 cuboctahedra, and faces with eight equivalent Ce(3)Ce8Mg4 cuboctahedra. Both Ce(2)-Ce(2) bond lengths are 3.25 Å. Both Ce(2)-Ce(3) bond lengths are 3.47 Å. In the third Ce site, Ce(3) is bonded to four equivalent Mg(1), two equivalent Ce(2), two equivalent Ce(3), and four equivalent Ce(1) atoms to form CeCe8Mg4 cuboctahedra that share corners with eight equivalent Mg(1)Ce10Mg2 cuboctahedra, corners with ten equivalent Ce(3)Ce8Mg4 cuboctahedra, edges with two equivalent Ce(3)Ce8Mg4 cuboctahedra, edges with four equivalent Mg(1)Ce10Mg2 cuboctahedra, edges with four equivalent Ce(2)Ce8Mg4 cuboctahedra, edges with eight equivalent Ce(1)Ce10Mg2 cuboctahedra, faces with four equivalent Mg(1)Ce10Mg2 cuboctahedra, faces with four equivalent Ce(1)Ce10Mg2 cuboctahedra, faces with four equivalent Ce(3)Ce8Mg4 cuboctahedra, and faces with eight equivalent Ce(2)Ce8Mg4 cuboctahedra. Both Ce(3)-Ce(3) bond lengths are 3.25 Å.