Sr5Mg is beta-derived structured and crystallizes in the trigonal R32 space group. There are five inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent Sr(2); six Sr(1,1); and two equivalent Mg(1) atoms to form distorted SrSr10Mg2 cuboctahedra that share corners with eighteen Sr(1,1,1,1)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 Sr(1,1,1)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 Sr(1,1,1); and three equivalent Mg(1) atoms to form distorted SrSr9Mg3 cuboctahedra that share corners with six equivalent Mg(1)Sr12 cuboctahedra; corners with twelve equivalent Sr(2)Sr9Mg3 cuboctahedra; edges with six equivalent Sr(2)Sr9Mg3 cuboctahedra; edges with twelve Sr(1,1,1)Sr10Mg2 cuboctahedra; faces with four equivalent Sr(2)Sr9Mg3 cuboctahedra; faces with four equivalent Mg(1)Sr12 cuboctahedra; and faces with twelve Sr(1,1,1)Sr10Mg2 cuboctahedra. In the third 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 Sr(1,1)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 Sr(1,1)Sr10Mg2 cuboctahedra; and faces with eight equivalent Sr(2)Sr9Mg3 cuboctahedra. In the fourth Sr site, Sr(1) is bonded to four equivalent Sr(2); six Sr(1,1); and two equivalent Mg(1) atoms to form distorted SrSr10Mg2 cuboctahedra that share corners with eighteen Sr(1,1,1,1)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 Sr(1,1)Sr10Mg2 cuboctahedra; and faces with eight equivalent Sr(2)Sr9Mg3 cuboctahedra. In the fifth Sr site, Sr(1) is bonded to four equivalent Sr(2); six Sr(1,1); and two equivalent Mg(1) atoms to form distorted SrSr10Mg2 cuboctahedra that share corners with eighteen Sr(1,1)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 Sr(1,1,1)Sr10Mg2 cuboctahedra; and faces with eight equivalent Sr(2)Sr9Mg3 cuboctahedra. Mg(1) is bonded to six Sr(1,1,1) and six equivalent Sr(2) atoms to form distorted MgSr12 cuboctahedra that share corners with six equivalent Mg(1)Sr12 cuboctahedra; corners with twelve equivalent Sr(2)Sr9Mg3 cuboctahedra; edges with six equivalent Mg(1)Sr12 cuboctahedra; edges with twelve Sr(1,1,1)Sr10Mg2 cuboctahedra; faces with eight equivalent Sr(2)Sr9Mg3 cuboctahedra; and faces with twelve Sr(1,1,1)Sr10Mg2 cuboctahedra.
Sr5Mg is beta-derived structured and crystallizes in the trigonal R32 space group. There are five inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent Sr(2); six Sr(1,1); and two equivalent Mg(1) atoms to form distorted SrSr10Mg2 cuboctahedra that share corners with eighteen Sr(1,1,1,1)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 Sr(1,1,1)Sr10Mg2 cuboctahedra; and faces with eight equivalent Sr(2)Sr9Mg3 cuboctahedra. There are two shorter (4.15 Å) and two longer (4.16 Å) Sr(1)-Sr(2) bond lengths. There are four shorter (4.07 Å) and two longer (4.15 Å) Sr(1)-Sr(1,1) bond lengths. Both Sr(1)-Mg(1) bond lengths are 4.14 Å. In the second Sr site, Sr(2) is bonded to three equivalent Sr(2); six Sr(1,1,1); and three equivalent Mg(1) atoms to form distorted SrSr9Mg3 cuboctahedra that share corners with six equivalent Mg(1)Sr12 cuboctahedra; corners with twelve equivalent Sr(2)Sr9Mg3 cuboctahedra; edges with six equivalent Sr(2)Sr9Mg3 cuboctahedra; edges with twelve Sr(1,1,1)Sr10Mg2 cuboctahedra; faces with four equivalent Sr(2)Sr9Mg3 cuboctahedra; faces with four equivalent Mg(1)Sr12 cuboctahedra; and faces with twelve Sr(1,1,1)Sr10Mg2 cuboctahedra. All Sr(2)-Sr(2) bond lengths are 4.10 Å. There is one shorter (4.15 Å) and one longer (4.16 Å) Sr(2)-Sr(1,1) bond length. All Sr(2)-Mg(1) bond lengths are 4.10 Å. In the third 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 Sr(1,1)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 Sr(1,1)Sr10Mg2 cuboctahedra; and faces with eight equivalent Sr(2)Sr9Mg3 cuboctahedra. Both Sr(1)-Mg(1) bond lengths are 4.14 Å. In the fourth Sr site, Sr(1) is bonded to four equivalent Sr(2); six Sr(1,1); and two equivalent Mg(1) atoms to form distorted SrSr10Mg2 cuboctahedra that share corners with eighteen Sr(1,1,1,1)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 Sr(1,1)Sr10Mg2 cuboctahedra; and faces with eight equivalent Sr(2)Sr9Mg3 cuboctahedra. There are four shorter (4.07 Å) and two longer (4.15 Å) Sr(1)-Sr(1,1) bond lengths. Both Sr(1)-Mg(1) bond lengths are 4.14 Å. In the fifth Sr site, Sr(1) is bonded to four equivalent Sr(2); six Sr(1,1); and two equivalent Mg(1) atoms to form distorted SrSr10Mg2 cuboctahedra that share corners with eighteen Sr(1,1)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 Sr(1,1,1)Sr10Mg2 cuboctahedra; and faces with eight equivalent Sr(2)Sr9Mg3 cuboctahedra. There are two shorter (4.15 Å) and two longer (4.16 Å) Sr(1)-Sr(2) bond lengths. There are two shorter (4.07 Å) and one longer (4.15 Å) Sr(1)-Sr(1) bond length. Both Sr(1)-Mg(1) bond lengths are 4.14 Å. Mg(1) is bonded to six Sr(1,1,1) and six equivalent Sr(2) atoms to form distorted MgSr12 cuboctahedra that share corners with six equivalent Mg(1)Sr12 cuboctahedra; corners with twelve equivalent Sr(2)Sr9Mg3 cuboctahedra; edges with six equivalent Mg(1)Sr12 cuboctahedra; edges with twelve Sr(1,1,1)Sr10Mg2 cuboctahedra; faces with eight equivalent Sr(2)Sr9Mg3 cuboctahedra; and faces with twelve Sr(1,1,1)Sr10Mg2 cuboctahedra.