RbMg14Cr crystallizes in the orthorhombic Amm2 space group. Rb(1) is bonded to two equivalent Mg(6); four Mg(3,3); four Mg(5,5); and two equivalent Cr(1) atoms to form RbMg10Cr2 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra; corners with six equivalent Rb(1)Mg10Cr2 cuboctahedra; corners with eight equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Cr(1)Rb2Mg10 cuboctahedra; edges with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with four equivalent Mg(6)RbMg11 cuboctahedra; edges with eight Mg(5,5)RbMg10Cr cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with two equivalent Cr(1)Rb2Mg10 cuboctahedra; faces with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; faces with four Mg(5,5)RbMg10Cr cuboctahedra; and faces with six equivalent Mg(7)Mg11Cr cuboctahedra. There are nine inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2); two equivalent Mg(6); four equivalent Mg(4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Cr(1)Rb2Mg10 cuboctahedra; corners with six equivalent Mg(1)Mg12 cuboctahedra; corners with eight Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with four equivalent Mg(6)RbMg11 cuboctahedra; edges with eight Mg(5,5)RbMg10Cr cuboctahedra; faces with two equivalent Rb(1)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with four equivalent Mg(4)Mg12 cuboctahedra; faces with four Mg(5,5)RbMg10Cr cuboctahedra; and faces with six equivalent Mg(7)Mg11Cr cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1); two equivalent Mg(7); four equivalent Mg(4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Rb(1)Mg10Cr2 cuboctahedra; corners with six equivalent Mg(2)Mg12 cuboctahedra; corners with eight Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with four equivalent Mg(7)Mg11Cr cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with eight Mg(5,5)RbMg10Cr cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Cr(1)Rb2Mg10 cuboctahedra; faces with four equivalent Mg(4)Mg12 cuboctahedra; faces with four Mg(5,5)RbMg10Cr cuboctahedra; and faces with six equivalent Mg(6)RbMg11 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Rb(1), two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and two equivalent Cr(1) atoms to form distorted MgRb2Mg8Cr2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with four equivalent Mg(2)Mg12 cuboctahedra; corners with four equivalent Mg(4)Mg12 cuboctahedra; corners with six Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Rb(1)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Cr(1)Rb2Mg10 cuboctahedra; edges with four equivalent Mg(7)Mg11Cr cuboctahedra; edges with four equivalent Mg(5)RbMg10Cr cuboctahedra; edges with four equivalent Mg(6)RbMg11 cuboctahedra; faces with two equivalent Rb(1)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with two equivalent Cr(1)Rb2Mg10 cuboctahedra; and faces with eight Mg(5,5)RbMg10Cr cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), two equivalent Mg(6), and two equivalent Mg(7) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Rb(1)Mg10Cr2 cuboctahedra; corners with four equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; corners with four equivalent Cr(1)Rb2Mg10 cuboctahedra; corners with six equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with four equivalent Mg(7)Mg11Cr cuboctahedra; edges with four equivalent Mg(5)RbMg10Cr cuboctahedra; edges with four equivalent Mg(6)RbMg11 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; and faces with eight Mg(5,5)RbMg10Cr cuboctahedra. In the fifth Mg site, Mg(5) is bonded to one Rb(1), one Mg(1), one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and one Cr(1) atom to form distorted MgRbMg10Cr cuboctahedra that share corners with four equivalent Mg(7)Mg11Cr cuboctahedra; corners with four equivalent Mg(6)RbMg11 cuboctahedra; corners with ten Mg(5,5)RbMg10Cr cuboctahedra; edges with two equivalent Rb(1)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(7)Mg11Cr cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Mg(5)RbMg10Cr cuboctahedra; edges with two equivalent Mg(6)RbMg11 cuboctahedra; edges with two equivalent Cr(1)Rb2Mg10 cuboctahedra;  a faceface with one Rb(1)Mg10Cr2 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Cr(1)Rb2Mg10 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with four equivalent Mg(4)Mg12 cuboctahedra; faces with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; and faces with four Mg(5,5)RbMg10Cr cuboctahedra. In the sixth Mg site, Mg(6) is bonded to one Rb(1); one Mg(1); two Mg(3,3); two equivalent Mg(4); two equivalent Mg(7); and four Mg(5,5) atoms to form distorted MgRbMg11 cuboctahedra that share corners with four equivalent Mg(7)Mg11Cr cuboctahedra; corners with six equivalent Mg(6)RbMg11 cuboctahedra; corners with eight Mg(5,5)RbMg10Cr cuboctahedra; edges with two equivalent Rb(1)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(7)Mg11Cr cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with four Mg(5,5)RbMg10Cr cuboctahedra;  a faceface with one Rb(1)Mg10Cr2 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two Mg(3,3)Rb2Mg8Cr2 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with three equivalent Mg(2)Mg12 cuboctahedra; faces with three equivalent Cr(1)Rb2Mg10 cuboctahedra; and faces with four Mg(5,5)RbMg10Cr cuboctahedra. In the seventh Mg site, Mg(7) is bonded to one Mg(2); two Mg(3,3); two equivalent Mg(4); two equivalent Mg(6); four Mg(5,5); and one Cr(1) atom to form distorted MgMg11Cr cuboctahedra that share corners with four equivalent Mg(6)RbMg11 cuboctahedra; corners with six equivalent Mg(7)Mg11Cr cuboctahedra; corners with eight Mg(5,5)RbMg10Cr cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(6)RbMg11 cuboctahedra; edges with two equivalent Cr(1)Rb2Mg10 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with four Mg(5,5)RbMg10Cr cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Cr(1)Rb2Mg10 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two Mg(3,3)Rb2Mg8Cr2 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with three equivalent Rb(1)Mg10Cr2 cuboctahedra; faces with three equivalent Mg(1)Mg12 cuboctahedra; and faces with four Mg(5,5)RbMg10Cr cuboctahedra. In the eighth Mg site, Mg(3) is bonded to two equivalent Rb(1), two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and two equivalent Cr(1) atoms to form distorted MgRb2Mg8Cr2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with four equivalent Mg(2)Mg12 cuboctahedra; corners with four equivalent Mg(4)Mg12 cuboctahedra; corners with six Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Rb(1)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Cr(1)Rb2Mg10 cuboctahedra; edges with four equivalent Mg(7)Mg11Cr cuboctahedra; edges with four equivalent Mg(5)RbMg10Cr cuboctahedra; edges with four equivalent Mg(6)RbMg11 cuboctahedra; faces with two equivalent Rb(1)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with two equivalent Cr(1)Rb2Mg10 cuboctahedra; and faces with eight Mg(5,5)RbMg10Cr cuboctahedra. In the ninth Mg site, Mg(5) is bonded to one Rb(1), one Mg(1), one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and one Cr(1) atom to form distorted MgRbMg10Cr cuboctahedra that share corners with four equivalent Mg(7)Mg11Cr cuboctahedra; corners with four equivalent Mg(6)RbMg11 cuboctahedra; corners with ten Mg(5,5)RbMg10Cr cuboctahedra; edges with two equivalent Rb(1)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(7)Mg11Cr cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Mg(5)RbMg10Cr cuboctahedra; edges with two equivalent Mg(6)RbMg11 cuboctahedra; edges with two equivalent Cr(1)Rb2Mg10 cuboctahedra;  a faceface with one Rb(1)Mg10Cr2 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Cr(1)Rb2Mg10 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with four equivalent Mg(4)Mg12 cuboctahedra; faces with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; and faces with four Mg(5,5)RbMg10Cr cuboctahedra. Cr(1) is bonded to two equivalent Rb(1); two equivalent Mg(7); four Mg(3,3); and four Mg(5,5) atoms to form CrRb2Mg10 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with six equivalent Cr(1)Rb2Mg10 cuboctahedra; corners with eight equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Rb(1)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(7)Mg11Cr cuboctahedra; edges with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with eight Mg(5,5)RbMg10Cr cuboctahedra; faces with two equivalent Rb(1)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; faces with four Mg(5,5)RbMg10Cr cuboctahedra; and faces with six equivalent Mg(6)RbMg11 cuboctahedra.
RbMg14Cr crystallizes in the orthorhombic Amm2 space group. Rb(1) is bonded to two equivalent Mg(6); four Mg(3,3); four Mg(5,5); and two equivalent Cr(1) atoms to form RbMg10Cr2 cuboctahedra that share corners with four equivalent Mg(2)Mg12 cuboctahedra; corners with six equivalent Rb(1)Mg10Cr2 cuboctahedra; corners with eight equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Cr(1)Rb2Mg10 cuboctahedra; edges with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with four equivalent Mg(6)RbMg11 cuboctahedra; edges with eight Mg(5,5)RbMg10Cr cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with two equivalent Cr(1)Rb2Mg10 cuboctahedra; faces with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; faces with four Mg(5,5)RbMg10Cr cuboctahedra; and faces with six equivalent Mg(7)Mg11Cr cuboctahedra. Both Rb(1)-Mg(6) bond lengths are 3.44 Å. All Rb(1)-Mg(3,3) bond lengths are 3.25 Å. All Rb(1)-Mg(5,5) bond lengths are 3.41 Å. Both Rb(1)-Cr(1) bond lengths are 3.27 Å. There are nine inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(2); two equivalent Mg(6); four equivalent Mg(4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Cr(1)Rb2Mg10 cuboctahedra; corners with six equivalent Mg(1)Mg12 cuboctahedra; corners with eight Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with four equivalent Mg(6)RbMg11 cuboctahedra; edges with eight Mg(5,5)RbMg10Cr cuboctahedra; faces with two equivalent Rb(1)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with four equivalent Mg(4)Mg12 cuboctahedra; faces with four Mg(5,5)RbMg10Cr cuboctahedra; and faces with six equivalent Mg(7)Mg11Cr cuboctahedra. Both Mg(1)-Mg(2) bond lengths are 3.27 Å. Both Mg(1)-Mg(6) bond lengths are 3.15 Å. There are two shorter (3.23 Å) and two longer (3.26 Å) Mg(1)-Mg(4) bond lengths. All Mg(1)-Mg(5,5) bond lengths are 3.21 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(1); two equivalent Mg(7); four equivalent Mg(4); and four Mg(5,5) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Rb(1)Mg10Cr2 cuboctahedra; corners with six equivalent Mg(2)Mg12 cuboctahedra; corners with eight Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with four equivalent Mg(7)Mg11Cr cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with eight Mg(5,5)RbMg10Cr cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Cr(1)Rb2Mg10 cuboctahedra; faces with four equivalent Mg(4)Mg12 cuboctahedra; faces with four Mg(5,5)RbMg10Cr cuboctahedra; and faces with six equivalent Mg(6)RbMg11 cuboctahedra. Both Mg(2)-Mg(7) bond lengths are 3.31 Å. There are two shorter (3.23 Å) and two longer (3.27 Å) Mg(2)-Mg(4) bond lengths. All Mg(2)-Mg(5,5) bond lengths are 3.14 Å. In the third Mg site, Mg(3) is bonded to two equivalent Rb(1), two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and two equivalent Cr(1) atoms to form distorted MgRb2Mg8Cr2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with four equivalent Mg(2)Mg12 cuboctahedra; corners with four equivalent Mg(4)Mg12 cuboctahedra; corners with six Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Rb(1)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Cr(1)Rb2Mg10 cuboctahedra; edges with four equivalent Mg(7)Mg11Cr cuboctahedra; edges with four equivalent Mg(5)RbMg10Cr cuboctahedra; edges with four equivalent Mg(6)RbMg11 cuboctahedra; faces with two equivalent Rb(1)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with two equivalent Cr(1)Rb2Mg10 cuboctahedra; and faces with eight Mg(5,5)RbMg10Cr cuboctahedra. There is one shorter (3.23 Å) and one longer (3.32 Å) Mg(3)-Mg(3) bond length. Both Mg(3)-Mg(5) bond lengths are 3.34 Å. Both Mg(3)-Mg(6) bond lengths are 3.39 Å. Both Mg(3)-Mg(7) bond lengths are 3.22 Å. There is one shorter (3.20 Å) and one longer (3.30 Å) Mg(3)-Cr(1) bond length. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(4), two equivalent Mg(5), two equivalent Mg(6), and two equivalent Mg(7) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Rb(1)Mg10Cr2 cuboctahedra; corners with four equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; corners with four equivalent Cr(1)Rb2Mg10 cuboctahedra; corners with six equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with four equivalent Mg(7)Mg11Cr cuboctahedra; edges with four equivalent Mg(5)RbMg10Cr cuboctahedra; edges with four equivalent Mg(6)RbMg11 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; and faces with eight Mg(5,5)RbMg10Cr cuboctahedra. There is one shorter (3.24 Å) and one longer (3.31 Å) Mg(4)-Mg(4) bond length. Both Mg(4)-Mg(5) bond lengths are 3.15 Å. Both Mg(4)-Mg(6) bond lengths are 3.11 Å. Both Mg(4)-Mg(7) bond lengths are 3.33 Å. In the fifth Mg site, Mg(5) is bonded to one Rb(1), one Mg(1), one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and one Cr(1) atom to form distorted MgRbMg10Cr cuboctahedra that share corners with four equivalent Mg(7)Mg11Cr cuboctahedra; corners with four equivalent Mg(6)RbMg11 cuboctahedra; corners with ten Mg(5,5)RbMg10Cr cuboctahedra; edges with two equivalent Rb(1)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(7)Mg11Cr cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Mg(5)RbMg10Cr cuboctahedra; edges with two equivalent Mg(6)RbMg11 cuboctahedra; edges with two equivalent Cr(1)Rb2Mg10 cuboctahedra;  a faceface with one Rb(1)Mg10Cr2 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Cr(1)Rb2Mg10 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with four equivalent Mg(4)Mg12 cuboctahedra; faces with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; and faces with four Mg(5,5)RbMg10Cr cuboctahedra. There is one shorter (3.13 Å) and one longer (3.41 Å) Mg(5)-Mg(5) bond length. There is one shorter (3.14 Å) and one longer (3.35 Å) Mg(5)-Mg(6) bond length. There is one shorter (3.22 Å) and one longer (3.29 Å) Mg(5)-Mg(7) bond length. The Mg(5)-Cr(1) bond length is 3.33 Å. In the sixth Mg site, Mg(6) is bonded to one Rb(1); one Mg(1); two Mg(3,3); two equivalent Mg(4); two equivalent Mg(7); and four Mg(5,5) atoms to form distorted MgRbMg11 cuboctahedra that share corners with four equivalent Mg(7)Mg11Cr cuboctahedra; corners with six equivalent Mg(6)RbMg11 cuboctahedra; corners with eight Mg(5,5)RbMg10Cr cuboctahedra; edges with two equivalent Rb(1)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(7)Mg11Cr cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with four Mg(5,5)RbMg10Cr cuboctahedra;  a faceface with one Rb(1)Mg10Cr2 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two Mg(3,3)Rb2Mg8Cr2 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with three equivalent Mg(2)Mg12 cuboctahedra; faces with three equivalent Cr(1)Rb2Mg10 cuboctahedra; and faces with four Mg(5,5)RbMg10Cr cuboctahedra. The Mg(6)-Mg(3) bond length is 3.39 Å. Both Mg(6)-Mg(7) bond lengths are 3.29 Å. There is one shorter (3.14 Å) and one longer (3.35 Å) Mg(6)-Mg(5) bond length. In the seventh Mg site, Mg(7) is bonded to one Mg(2); two Mg(3,3); two equivalent Mg(4); two equivalent Mg(6); four Mg(5,5); and one Cr(1) atom to form distorted MgMg11Cr cuboctahedra that share corners with four equivalent Mg(6)RbMg11 cuboctahedra; corners with six equivalent Mg(7)Mg11Cr cuboctahedra; corners with eight Mg(5,5)RbMg10Cr cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(6)RbMg11 cuboctahedra; edges with two equivalent Cr(1)Rb2Mg10 cuboctahedra; edges with four equivalent Mg(4)Mg12 cuboctahedra; edges with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with four Mg(5,5)RbMg10Cr cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Cr(1)Rb2Mg10 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two Mg(3,3)Rb2Mg8Cr2 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with three equivalent Rb(1)Mg10Cr2 cuboctahedra; faces with three equivalent Mg(1)Mg12 cuboctahedra; and faces with four Mg(5,5)RbMg10Cr cuboctahedra. The Mg(7)-Mg(3) bond length is 3.22 Å. There is one shorter (3.22 Å) and one longer (3.29 Å) Mg(7)-Mg(5) bond length. The Mg(7)-Cr(1) bond length is 3.19 Å. In the eighth Mg site, Mg(3) is bonded to two equivalent Rb(1), two equivalent Mg(3), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and two equivalent Cr(1) atoms to form distorted MgRb2Mg8Cr2 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with four equivalent Mg(2)Mg12 cuboctahedra; corners with four equivalent Mg(4)Mg12 cuboctahedra; corners with six Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Rb(1)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Cr(1)Rb2Mg10 cuboctahedra; edges with four equivalent Mg(7)Mg11Cr cuboctahedra; edges with four equivalent Mg(5)RbMg10Cr cuboctahedra; edges with four equivalent Mg(6)RbMg11 cuboctahedra; faces with two equivalent Rb(1)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(4)Mg12 cuboctahedra; faces with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with two equivalent Cr(1)Rb2Mg10 cuboctahedra; and faces with eight Mg(5,5)RbMg10Cr cuboctahedra. Both Mg(3)-Mg(5) bond lengths are 3.34 Å. There is one shorter (3.20 Å) and one longer (3.30 Å) Mg(3)-Cr(1) bond length. In the ninth Mg site, Mg(5) is bonded to one Rb(1), one Mg(1), one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(5), two equivalent Mg(6), two equivalent Mg(7), and one Cr(1) atom to form distorted MgRbMg10Cr cuboctahedra that share corners with four equivalent Mg(7)Mg11Cr cuboctahedra; corners with four equivalent Mg(6)RbMg11 cuboctahedra; corners with ten Mg(5,5)RbMg10Cr cuboctahedra; edges with two equivalent Rb(1)Mg10Cr2 cuboctahedra; edges with two equivalent Mg(7)Mg11Cr cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(2)Mg12 cuboctahedra; edges with two equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Mg(3)Rb2Mg8Cr2 cuboctahedra; edges with two equivalent Mg(5)RbMg10Cr cuboctahedra; edges with two equivalent Mg(6)RbMg11 cuboctahedra; edges with two equivalent Cr(1)Rb2Mg10 cuboctahedra;  a faceface with one Rb(1)Mg10Cr2 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Mg(2)Mg12 cuboctahedra;  a faceface with one Cr(1)Rb2Mg10 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(6)RbMg11 cuboctahedra; faces with four equivalent Mg(4)Mg12 cuboctahedra; faces with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; and faces with four Mg(5,5)RbMg10Cr cuboctahedra. The Mg(5)-Mg(4) bond length is 3.15 Å. The Mg(5)-Cr(1) bond length is 3.33 Å. Cr(1) is bonded to two equivalent Rb(1); two equivalent Mg(7); four Mg(3,3); and four Mg(5,5) atoms to form CrRb2Mg10 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with six equivalent Cr(1)Rb2Mg10 cuboctahedra; corners with eight equivalent Mg(4)Mg12 cuboctahedra; edges with two equivalent Rb(1)Mg10Cr2 cuboctahedra; edges with four equivalent Mg(7)Mg11Cr cuboctahedra; edges with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; edges with eight Mg(5,5)RbMg10Cr cuboctahedra; faces with two equivalent Rb(1)Mg10Cr2 cuboctahedra; faces with two equivalent Mg(7)Mg11Cr cuboctahedra; faces with two equivalent Mg(2)Mg12 cuboctahedra; faces with four Mg(3,3)Rb2Mg8Cr2 cuboctahedra; faces with four Mg(5,5)RbMg10Cr cuboctahedra; and faces with six equivalent Mg(6)RbMg11 cuboctahedra.