CaMg2Bi2 crystallizes in the trigonal P-3m1 space group. Ca(1) is bonded to six equivalent Bi(1) atoms to form CaBi6 octahedra that share corners with twelve equivalent Mg(1)Bi4 tetrahedra, edges with six equivalent Ca(1)Bi6 octahedra, and edges with six equivalent Mg(1)Bi4 tetrahedra. Mg(1) is bonded to four equivalent Bi(1) atoms to form MgBi4 tetrahedra that share corners with six equivalent Ca(1)Bi6 octahedra, corners with six equivalent Mg(1)Bi4 tetrahedra, edges with three equivalent Ca(1)Bi6 octahedra, and edges with three equivalent Mg(1)Bi4 tetrahedra. The corner-sharing octahedral tilt angles range from 14-56°. Bi(1) is bonded to three equivalent Ca(1) and four equivalent Mg(1) atoms to form a mixture of distorted corner and edge-sharing BiCa3Mg4 pentagonal bipyramids.
CaMg2Bi2 crystallizes in the trigonal P-3m1 space group. Ca(1) is bonded to six equivalent Bi(1) atoms to form CaBi6 octahedra that share corners with twelve equivalent Mg(1)Bi4 tetrahedra, edges with six equivalent Ca(1)Bi6 octahedra, and edges with six equivalent Mg(1)Bi4 tetrahedra. All Ca(1)-Bi(1) bond lengths are 3.32 Å. Mg(1) is bonded to four equivalent Bi(1) atoms to form MgBi4 tetrahedra that share corners with six equivalent Ca(1)Bi6 octahedra, corners with six equivalent Mg(1)Bi4 tetrahedra, edges with three equivalent Ca(1)Bi6 octahedra, and edges with three equivalent Mg(1)Bi4 tetrahedra. The corner-sharing octahedral tilt angles range from 14-56°. There are three shorter (2.93 Å) and one longer (2.98 Å) Mg(1)-Bi(1) bond length. Bi(1) is bonded to three equivalent Ca(1) and four equivalent Mg(1) atoms to form a mixture of distorted corner and edge-sharing BiCa3Mg4 pentagonal bipyramids.