Sr5Mg is beta-derived structured and crystallizes in the hexagonal P-62m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent Sr(2), six equivalent Sr(1), and two equivalent Mg(1) atoms to form distorted SrSr10Mg2 cuboctahedra that share corners with eighteen equivalent Sr(1)Sr10Mg2 cuboctahedra, edges with four equivalent Mg(1)Sr12 cuboctahedra, edges with six equivalent Sr(1)Sr10Mg2 cuboctahedra, edges with eight equivalent Sr(2)Sr9Mg3 cuboctahedra, faces with four equivalent Mg(1)Sr12 cuboctahedra, faces with eight equivalent Sr(1)Sr10Mg2 cuboctahedra, and faces with eight equivalent Sr(2)Sr9Mg3 cuboctahedra. In the second Sr site, Sr(2) is bonded to three equivalent Sr(2), six equivalent Sr(1), and three equivalent Mg(1) atoms to form SrSr9Mg3 cuboctahedra that share corners with nine equivalent Sr(2)Sr9Mg3 cuboctahedra, corners with nine equivalent Mg(1)Sr12 cuboctahedra, edges with six equivalent Sr(2)Sr9Mg3 cuboctahedra, edges with twelve equivalent Sr(1)Sr10Mg2 cuboctahedra, faces with three equivalent Mg(1)Sr12 cuboctahedra, faces with five equivalent Sr(2)Sr9Mg3 cuboctahedra, and faces with twelve equivalent Sr(1)Sr10Mg2 cuboctahedra. Mg(1) is bonded to six equivalent Sr(1) and six equivalent Sr(2) atoms to form MgSr12 cuboctahedra that share corners with eighteen equivalent Sr(2)Sr9Mg3 cuboctahedra, edges with six equivalent Mg(1)Sr12 cuboctahedra, edges with twelve equivalent Sr(1)Sr10Mg2 cuboctahedra, faces with two equivalent Mg(1)Sr12 cuboctahedra, faces with six equivalent Sr(2)Sr9Mg3 cuboctahedra, and faces with twelve equivalent Sr(1)Sr10Mg2 cuboctahedra.
Sr5Mg is beta-derived structured and crystallizes in the hexagonal P-62m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent Sr(2), six equivalent Sr(1), and two equivalent Mg(1) atoms to form distorted SrSr10Mg2 cuboctahedra that share corners with eighteen equivalent Sr(1)Sr10Mg2 cuboctahedra, edges with four equivalent Mg(1)Sr12 cuboctahedra, edges with six equivalent Sr(1)Sr10Mg2 cuboctahedra, edges with eight equivalent Sr(2)Sr9Mg3 cuboctahedra, faces with four equivalent Mg(1)Sr12 cuboctahedra, faces with eight equivalent Sr(1)Sr10Mg2 cuboctahedra, and faces with eight equivalent Sr(2)Sr9Mg3 cuboctahedra. All Sr(1)-Sr(2) bond lengths are 4.12 Å. There are two shorter (3.90 Å) and four longer (4.20 Å) Sr(1)-Sr(1) bond lengths. Both Sr(1)-Mg(1) bond lengths are 4.02 Å. In the second Sr site, Sr(2) is bonded to three equivalent Sr(2), six equivalent Sr(1), and three equivalent Mg(1) atoms to form SrSr9Mg3 cuboctahedra that share corners with nine equivalent Sr(2)Sr9Mg3 cuboctahedra, corners with nine equivalent Mg(1)Sr12 cuboctahedra, edges with six equivalent Sr(2)Sr9Mg3 cuboctahedra, edges with twelve equivalent Sr(1)Sr10Mg2 cuboctahedra, faces with three equivalent Mg(1)Sr12 cuboctahedra, faces with five equivalent Sr(2)Sr9Mg3 cuboctahedra, and faces with twelve equivalent Sr(1)Sr10Mg2 cuboctahedra. All Sr(2)-Sr(2) bond lengths are 4.10 Å. All Sr(2)-Mg(1) bond lengths are 4.10 Å. Mg(1) is bonded to six equivalent Sr(1) and six equivalent Sr(2) atoms to form MgSr12 cuboctahedra that share corners with eighteen equivalent Sr(2)Sr9Mg3 cuboctahedra, edges with six equivalent Mg(1)Sr12 cuboctahedra, edges with twelve equivalent Sr(1)Sr10Mg2 cuboctahedra, faces with two equivalent Mg(1)Sr12 cuboctahedra, faces with six equivalent Sr(2)Sr9Mg3 cuboctahedra, and faces with twelve equivalent Sr(1)Sr10Mg2 cuboctahedra.