SrMg6Cr 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 Cr(1) atoms to form SrMg10Cr2 cuboctahedra that share corners with four equivalent Cr(1)Sr2Mg10 cuboctahedra, corners with six equivalent Sr(1)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra, edges with two equivalent Cr(1)Sr2Mg10 cuboctahedra, edges with four equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra, faces with two equivalent Sr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Sr2Mg8Cr2 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 Cr(1) atoms to form distorted MgSr2Mg8Cr2 cuboctahedra that share corners with four equivalent Sr(1)Mg10Cr2 cuboctahedra, corners with four equivalent Cr(1)Sr2Mg10 cuboctahedra, corners with ten equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra, edges with two equivalent Sr(1)Mg10Cr2 cuboctahedra, edges with two equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra, edges with two equivalent Cr(1)Sr2Mg10 cuboctahedra, faces with two equivalent Sr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to two equivalent Sr(1), two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Cr(1) atoms. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Sr(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(2) 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 Cr(1) atoms. Cr(1) is bonded to two equivalent Sr(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(2) atoms to form CrSr2Mg10 cuboctahedra that share corners with four equivalent Sr(1)Mg10Cr2 cuboctahedra, corners with six equivalent Cr(1)Sr2Mg10 cuboctahedra, corners with eight equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra, edges with two equivalent Sr(1)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra, faces with two equivalent Sr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra.
SrMg6Cr 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 Cr(1) atoms to form SrMg10Cr2 cuboctahedra that share corners with four equivalent Cr(1)Sr2Mg10 cuboctahedra, corners with six equivalent Sr(1)Mg10Cr2 cuboctahedra, corners with eight equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra, edges with two equivalent Cr(1)Sr2Mg10 cuboctahedra, edges with four equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra, faces with two equivalent Sr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra. Both Sr(1)-Mg(3) bond lengths are 3.32 Å. All Sr(1)-Mg(1) bond lengths are 3.34 Å. All Sr(1)-Mg(2) bond lengths are 3.33 Å. Both Sr(1)-Cr(1) bond lengths are 3.32 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 Cr(1) atoms to form distorted MgSr2Mg8Cr2 cuboctahedra that share corners with four equivalent Sr(1)Mg10Cr2 cuboctahedra, corners with four equivalent Cr(1)Sr2Mg10 cuboctahedra, corners with ten equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra, edges with two equivalent Sr(1)Mg10Cr2 cuboctahedra, edges with two equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra, edges with two equivalent Cr(1)Sr2Mg10 cuboctahedra, faces with two equivalent Sr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra. There is one shorter (3.25 Å) and one longer (3.38 Å) Mg(1)-Mg(1) bond length. Both Mg(1)-Mg(2) bond lengths are 3.24 Å. Both Mg(1)-Mg(3) bond lengths are 3.22 Å. Both Mg(1)-Mg(4) bond lengths are 3.29 Å. There is one shorter (3.29 Å) and one longer (3.39 Å) Mg(1)-Cr(1) bond length. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to two equivalent Sr(1), two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(4), and two equivalent Cr(1) atoms. There is one shorter (3.18 Å) and one longer (3.50 Å) Mg(2)-Mg(3) bond length. There is one shorter (3.25 Å) and one longer (3.43 Å) Mg(2)-Mg(4) bond length. Both Mg(2)-Cr(1) bond lengths are 3.19 Å. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Sr(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(2) atoms. Both Mg(3)-Mg(4) bond lengths are 3.32 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 Cr(1) atoms. Both Mg(4)-Cr(1) bond lengths are 3.24 Å. Cr(1) is bonded to two equivalent Sr(1), two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(2) atoms to form CrSr2Mg10 cuboctahedra that share corners with four equivalent Sr(1)Mg10Cr2 cuboctahedra, corners with six equivalent Cr(1)Sr2Mg10 cuboctahedra, corners with eight equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra, edges with two equivalent Sr(1)Mg10Cr2 cuboctahedra, edges with four equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra, faces with two equivalent Sr(1)Mg10Cr2 cuboctahedra, faces with two equivalent Cr(1)Sr2Mg10 cuboctahedra, and faces with four equivalent Mg(1)Sr2Mg8Cr2 cuboctahedra.