CsMg6Nb crystallizes in the tetragonal P4/mmm space group. Cs(1) is bonded to four equivalent Mg(1) and eight equivalent Mg(2) atoms to form CsMg12 cuboctahedra that share corners with four equivalent Cs(1)Mg12 cuboctahedra, corners with eight equivalent Nb(1)Mg12 cuboctahedra, edges with eight equivalent Mg(1)Cs2Mg8Nb2 cuboctahedra, faces with two equivalent Cs(1)Mg12 cuboctahedra, faces with four equivalent Mg(1)Cs2Mg8Nb2 cuboctahedra, and faces with four equivalent Nb(1)Mg12 cuboctahedra. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Cs(1), eight equivalent Mg(2), and two equivalent Nb(1) atoms to form MgCs2Mg8Nb2 cuboctahedra that share corners with twelve equivalent Mg(1)Cs2Mg8Nb2 cuboctahedra, edges with four equivalent Cs(1)Mg12 cuboctahedra, edges with four equivalent Nb(1)Mg12 cuboctahedra, faces with two equivalent Cs(1)Mg12 cuboctahedra, faces with two equivalent Nb(1)Mg12 cuboctahedra, and faces with six equivalent Mg(1)Cs2Mg8Nb2 cuboctahedra. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Cs(1), two equivalent Mg(2), four equivalent Mg(1), and two equivalent Nb(1) atoms. Nb(1) is bonded to four equivalent Mg(1) and eight equivalent Mg(2) atoms to form distorted NbMg12 cuboctahedra that share corners with four equivalent Nb(1)Mg12 cuboctahedra, corners with eight equivalent Cs(1)Mg12 cuboctahedra, edges with eight equivalent Mg(1)Cs2Mg8Nb2 cuboctahedra, faces with two equivalent Nb(1)Mg12 cuboctahedra, faces with four equivalent Cs(1)Mg12 cuboctahedra, and faces with four equivalent Mg(1)Cs2Mg8Nb2 cuboctahedra.
CsMg6Nb crystallizes in the tetragonal P4/mmm space group. Cs(1) is bonded to four equivalent Mg(1) and eight equivalent Mg(2) atoms to form CsMg12 cuboctahedra that share corners with four equivalent Cs(1)Mg12 cuboctahedra, corners with eight equivalent Nb(1)Mg12 cuboctahedra, edges with eight equivalent Mg(1)Cs2Mg8Nb2 cuboctahedra, faces with two equivalent Cs(1)Mg12 cuboctahedra, faces with four equivalent Mg(1)Cs2Mg8Nb2 cuboctahedra, and faces with four equivalent Nb(1)Mg12 cuboctahedra. All Cs(1)-Mg(1) bond lengths are 3.59 Å. All Cs(1)-Mg(2) bond lengths are 3.63 Å. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Cs(1), eight equivalent Mg(2), and two equivalent Nb(1) atoms to form MgCs2Mg8Nb2 cuboctahedra that share corners with twelve equivalent Mg(1)Cs2Mg8Nb2 cuboctahedra, edges with four equivalent Cs(1)Mg12 cuboctahedra, edges with four equivalent Nb(1)Mg12 cuboctahedra, faces with two equivalent Cs(1)Mg12 cuboctahedra, faces with two equivalent Nb(1)Mg12 cuboctahedra, and faces with six equivalent Mg(1)Cs2Mg8Nb2 cuboctahedra. All Mg(1)-Mg(2) bond lengths are 3.31 Å. Both Mg(1)-Nb(1) bond lengths are 3.59 Å. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Cs(1), two equivalent Mg(2), four equivalent Mg(1), and two equivalent Nb(1) atoms. Both Mg(2)-Mg(2) bond lengths are 2.97 Å. Both Mg(2)-Nb(1) bond lengths are 2.95 Å. Nb(1) is bonded to four equivalent Mg(1) and eight equivalent Mg(2) atoms to form distorted NbMg12 cuboctahedra that share corners with four equivalent Nb(1)Mg12 cuboctahedra, corners with eight equivalent Cs(1)Mg12 cuboctahedra, edges with eight equivalent Mg(1)Cs2Mg8Nb2 cuboctahedra, faces with two equivalent Nb(1)Mg12 cuboctahedra, faces with four equivalent Cs(1)Mg12 cuboctahedra, and faces with four equivalent Mg(1)Cs2Mg8Nb2 cuboctahedra.