Mg2Sr crystallizes in the hexagonal P-62m space group. Sr(1) is bonded to three equivalent Sr(1), three equivalent Mg(2), and six equivalent Mg(1) atoms to form distorted SrSr3Mg9 cuboctahedra that share corners with nine equivalent Sr(1)Sr3Mg9 cuboctahedra, corners with nine equivalent Mg(2)Sr6Mg6 cuboctahedra, edges with six equivalent Sr(1)Sr3Mg9 cuboctahedra, faces with three equivalent Mg(2)Sr6Mg6 cuboctahedra, and faces with five equivalent Sr(1)Sr3Mg9 cuboctahedra. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to four equivalent Sr(1), two equivalent Mg(1), and two equivalent Mg(2) atoms. In the second Mg site, Mg(2) is bonded to six equivalent Sr(1) and six equivalent Mg(1) atoms to form MgSr6Mg6 cuboctahedra that share corners with eighteen equivalent Sr(1)Sr3Mg9 cuboctahedra, edges with six equivalent Mg(2)Sr6Mg6 cuboctahedra, faces with two equivalent Mg(2)Sr6Mg6 cuboctahedra, and faces with six equivalent Sr(1)Sr3Mg9 cuboctahedra.
Mg2Sr crystallizes in the hexagonal P-62m space group. Sr(1) is bonded to three equivalent Sr(1), three equivalent Mg(2), and six equivalent Mg(1) atoms to form distorted SrSr3Mg9 cuboctahedra that share corners with nine equivalent Sr(1)Sr3Mg9 cuboctahedra, corners with nine equivalent Mg(2)Sr6Mg6 cuboctahedra, edges with six equivalent Sr(1)Sr3Mg9 cuboctahedra, faces with three equivalent Mg(2)Sr6Mg6 cuboctahedra, and faces with five equivalent Sr(1)Sr3Mg9 cuboctahedra. All Sr(1)-Sr(1) bond lengths are 3.66 Å. All Sr(1)-Mg(2) bond lengths are 3.66 Å. All Sr(1)-Mg(1) bond lengths are 3.61 Å. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to four equivalent Sr(1), two equivalent Mg(1), and two equivalent Mg(2) atoms. Both Mg(1)-Mg(1) bond lengths are 3.16 Å. Both Mg(1)-Mg(2) bond lengths are 3.35 Å. In the second Mg site, Mg(2) is bonded to six equivalent Sr(1) and six equivalent Mg(1) atoms to form MgSr6Mg6 cuboctahedra that share corners with eighteen equivalent Sr(1)Sr3Mg9 cuboctahedra, edges with six equivalent Mg(2)Sr6Mg6 cuboctahedra, faces with two equivalent Mg(2)Sr6Mg6 cuboctahedra, and faces with six equivalent Sr(1)Sr3Mg9 cuboctahedra.