K2MgCl4 is (La,Ba)CuO4 structured and crystallizes in the tetragonal I4/mmm space group. K(1) is bonded in a 9-coordinate geometry to four equivalent Cl(2) and five equivalent Cl(1) atoms. Mg(1) is bonded to two equivalent Cl(1) and four equivalent Cl(2) atoms to form corner-sharing MgCl6 octahedra. The corner-sharing octahedra are not tilted. There are two inequivalent Cl sites. In the first Cl site, Cl(2) is bonded to four equivalent K(1) and two equivalent Mg(1) atoms to form distorted ClK4Mg2 octahedra that share corners with two equivalent Cl(2)K4Mg2 octahedra, corners with twelve equivalent Cl(1)K5Mg octahedra, edges with two equivalent Cl(2)K4Mg2 octahedra, faces with four equivalent Cl(2)K4Mg2 octahedra, and faces with four equivalent Cl(1)K5Mg octahedra. The corner-sharing octahedral tilt angles range from 0-55°. In the second Cl site, Cl(1) is bonded to five equivalent K(1) and one Mg(1) atom to form distorted ClK5Mg octahedra that share corners with five equivalent Cl(1)K5Mg octahedra, corners with twelve equivalent Cl(2)K4Mg2 octahedra, edges with eight equivalent Cl(1)K5Mg octahedra, and faces with four equivalent Cl(2)K4Mg2 octahedra. The corner-sharing octahedral tilt angles range from 0-55°.
K2MgCl4 is (La,Ba)CuO4 structured and crystallizes in the tetragonal I4/mmm space group. K(1) is bonded in a 9-coordinate geometry to four equivalent Cl(2) and five equivalent Cl(1) atoms. All K(1)-Cl(2) bond lengths are 3.31 Å. There is one shorter (3.09 Å) and four longer (3.50 Å) K(1)-Cl(1) bond lengths. Mg(1) is bonded to two equivalent Cl(1) and four equivalent Cl(2) atoms to form corner-sharing MgCl6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(1)-Cl(1) bond lengths are 2.50 Å. All Mg(1)-Cl(2) bond lengths are 2.46 Å. There are two inequivalent Cl sites. In the first Cl site, Cl(2) is bonded to four equivalent K(1) and two equivalent Mg(1) atoms to form distorted ClK4Mg2 octahedra that share corners with two equivalent Cl(2)K4Mg2 octahedra, corners with twelve equivalent Cl(1)K5Mg octahedra, edges with two equivalent Cl(2)K4Mg2 octahedra, faces with four equivalent Cl(2)K4Mg2 octahedra, and faces with four equivalent Cl(1)K5Mg octahedra. The corner-sharing octahedral tilt angles range from 0-55°. In the second Cl site, Cl(1) is bonded to five equivalent K(1) and one Mg(1) atom to form distorted ClK5Mg octahedra that share corners with five equivalent Cl(1)K5Mg octahedra, corners with twelve equivalent Cl(2)K4Mg2 octahedra, edges with eight equivalent Cl(1)K5Mg octahedra, and faces with four equivalent Cl(2)K4Mg2 octahedra. The corner-sharing octahedral tilt angles range from 0-55°.