SrMg6Sb crystallizes in the orthorhombic Amm2 space group. Sr(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Sb(1) atoms to form SrMg10Sb2 cuboctahedra that share corners with four equivalent Sb(1)Sr2Mg10 cuboctahedra, corners with six equivalent Sr(1)Mg10Sb2 cuboctahedra, corners with eight equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra, edges with two equivalent Sb(1)Sr2Mg10 cuboctahedra, edges with four equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra, faces with two equivalent Sr(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Sr(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Sb(1) atoms to form distorted MgSr2Mg8Sb2 cuboctahedra that share corners with four equivalent Sr(1)Mg10Sb2 cuboctahedra, corners with four equivalent Sb(1)Sr2Mg10 cuboctahedra, corners with ten equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra, edges with two equivalent Sr(1)Mg10Sb2 cuboctahedra, edges with two equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra, edges with two equivalent Sb(1)Sr2Mg10 cuboctahedra, faces with two equivalent Sr(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to two equivalent Sr(1), one Mg(3), two equivalent Mg(1), two equivalent Mg(4), and two equivalent Sb(1) atoms. In the third Mg site, Mg(3) is bonded in a 10-coordinate geometry to two equivalent Sr(1), two equivalent Mg(2), two equivalent Mg(4), and four equivalent Mg(1) atoms. In the fourth Mg site, Mg(4) is bonded in a 12-coordinate geometry to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Sb(1) atoms. Sb(1) is bonded to two equivalent Sr(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(2) atoms to form distorted SbSr2Mg10 cuboctahedra that share corners with four equivalent Sr(1)Mg10Sb2 cuboctahedra, corners with six equivalent Sb(1)Sr2Mg10 cuboctahedra, corners with eight equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra, edges with two equivalent Sr(1)Mg10Sb2 cuboctahedra, edges with four equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra, faces with two equivalent Sr(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra.
SrMg6Sb crystallizes in the orthorhombic Amm2 space group. Sr(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Sb(1) atoms to form SrMg10Sb2 cuboctahedra that share corners with four equivalent Sb(1)Sr2Mg10 cuboctahedra, corners with six equivalent Sr(1)Mg10Sb2 cuboctahedra, corners with eight equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra, edges with two equivalent Sb(1)Sr2Mg10 cuboctahedra, edges with four equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra, faces with two equivalent Sr(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra. Both Sr(1)-Mg(3) bond lengths are 3.41 Å. There are two shorter (3.37 Å) and two longer (3.42 Å) Sr(1)-Mg(1) bond lengths. All Sr(1)-Mg(2) bond lengths are 3.38 Å. Both Sr(1)-Sb(1) bond lengths are 3.23 Å. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Sr(1), two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Sb(1) atoms to form distorted MgSr2Mg8Sb2 cuboctahedra that share corners with four equivalent Sr(1)Mg10Sb2 cuboctahedra, corners with four equivalent Sb(1)Sr2Mg10 cuboctahedra, corners with ten equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra, edges with two equivalent Sr(1)Mg10Sb2 cuboctahedra, edges with two equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra, edges with two equivalent Sb(1)Sr2Mg10 cuboctahedra, faces with two equivalent Sr(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra. There is one shorter (3.20 Å) and one longer (3.25 Å) Mg(1)-Mg(1) bond length. Both Mg(1)-Mg(2) bond lengths are 3.30 Å. Both Mg(1)-Mg(3) bond lengths are 3.28 Å. Both Mg(1)-Mg(4) bond lengths are 3.32 Å. There is one shorter (3.31 Å) and one longer (3.48 Å) Mg(1)-Sb(1) bond length. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to two equivalent Sr(1), one Mg(3), two equivalent Mg(1), two equivalent Mg(4), and two equivalent Sb(1) atoms. The Mg(2)-Mg(3) bond length is 3.19 Å. There is one shorter (3.32 Å) and one longer (3.48 Å) Mg(2)-Mg(4) bond length. Both Mg(2)-Sb(1) bond lengths are 3.29 Å. In the third Mg site, Mg(3) is bonded in a 10-coordinate geometry to two equivalent Sr(1), two equivalent Mg(2), two equivalent Mg(4), and four equivalent Mg(1) atoms. Both Mg(3)-Mg(4) bond lengths are 3.23 Å. In the fourth Mg site, Mg(4) is bonded in a 12-coordinate geometry to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Sb(1) atoms. Both Mg(4)-Sb(1) bond lengths are 3.42 Å. Sb(1) is bonded to two equivalent Sr(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(2) atoms to form distorted SbSr2Mg10 cuboctahedra that share corners with four equivalent Sr(1)Mg10Sb2 cuboctahedra, corners with six equivalent Sb(1)Sr2Mg10 cuboctahedra, corners with eight equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra, edges with two equivalent Sr(1)Mg10Sb2 cuboctahedra, edges with four equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra, faces with two equivalent Sr(1)Mg10Sb2 cuboctahedra, faces with two equivalent Sb(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Sr2Mg8Sb2 cuboctahedra.