KMg3 is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. K(1) is bonded to four equivalent Mg(1) and eight equivalent Mg(2) atoms to form distorted KMg12 cuboctahedra that share corners with four equivalent K(1)Mg12 cuboctahedra, corners with eight equivalent Mg(1)K4Mg8 cuboctahedra, edges with eight equivalent K(1)Mg12 cuboctahedra, faces with four equivalent K(1)Mg12 cuboctahedra, and faces with six equivalent Mg(1)K4Mg8 cuboctahedra. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to four equivalent K(1) and eight equivalent Mg(2) atoms to form MgK4Mg8 cuboctahedra that share corners with four equivalent Mg(1)K4Mg8 cuboctahedra, corners with eight equivalent K(1)Mg12 cuboctahedra, edges with eight equivalent Mg(1)K4Mg8 cuboctahedra, faces with four equivalent Mg(1)K4Mg8 cuboctahedra, and faces with six equivalent K(1)Mg12 cuboctahedra. In the second Mg site, Mg(2) is bonded in a distorted body-centered cubic geometry to four equivalent K(1) and four equivalent Mg(1) atoms.
KMg3 is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. K(1) is bonded to four equivalent Mg(1) and eight equivalent Mg(2) atoms to form distorted KMg12 cuboctahedra that share corners with four equivalent K(1)Mg12 cuboctahedra, corners with eight equivalent Mg(1)K4Mg8 cuboctahedra, edges with eight equivalent K(1)Mg12 cuboctahedra, faces with four equivalent K(1)Mg12 cuboctahedra, and faces with six equivalent Mg(1)K4Mg8 cuboctahedra. All K(1)-Mg(1) bond lengths are 3.75 Å. All K(1)-Mg(2) bond lengths are 3.40 Å. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to four equivalent K(1) and eight equivalent Mg(2) atoms to form MgK4Mg8 cuboctahedra that share corners with four equivalent Mg(1)K4Mg8 cuboctahedra, corners with eight equivalent K(1)Mg12 cuboctahedra, edges with eight equivalent Mg(1)K4Mg8 cuboctahedra, faces with four equivalent Mg(1)K4Mg8 cuboctahedra, and faces with six equivalent K(1)Mg12 cuboctahedra. All Mg(1)-Mg(2) bond lengths are 3.40 Å. In the second Mg site, Mg(2) is bonded in a distorted body-centered cubic geometry to four equivalent K(1) and four equivalent Mg(1) atoms.