MgAl2Ge2 crystallizes in the trigonal P-3m1 space group. Mg(1) is bonded to six equivalent Ge(1) atoms to form MgGe6 octahedra that share corners with twelve equivalent Al(1)Ge4 tetrahedra, edges with six equivalent Mg(1)Ge6 octahedra, and edges with six equivalent Al(1)Ge4 tetrahedra. Al(1) is bonded to four equivalent Ge(1) atoms to form AlGe4 tetrahedra that share corners with six equivalent Mg(1)Ge6 octahedra, corners with six equivalent Al(1)Ge4 tetrahedra, edges with three equivalent Mg(1)Ge6 octahedra, and edges with three equivalent Al(1)Ge4 tetrahedra. The corner-sharing octahedral tilt angles range from 15-55°. Ge(1) is bonded to three equivalent Mg(1) and four equivalent Al(1) atoms to form a mixture of distorted edge and corner-sharing GeMg3Al4 pentagonal bipyramids.
MgAl2Ge2 crystallizes in the trigonal P-3m1 space group. Mg(1) is bonded to six equivalent Ge(1) atoms to form MgGe6 octahedra that share corners with twelve equivalent Al(1)Ge4 tetrahedra, edges with six equivalent Mg(1)Ge6 octahedra, and edges with six equivalent Al(1)Ge4 tetrahedra. All Mg(1)-Ge(1) bond lengths are 2.88 Å. Al(1) is bonded to four equivalent Ge(1) atoms to form AlGe4 tetrahedra that share corners with six equivalent Mg(1)Ge6 octahedra, corners with six equivalent Al(1)Ge4 tetrahedra, edges with three equivalent Mg(1)Ge6 octahedra, and edges with three equivalent Al(1)Ge4 tetrahedra. The corner-sharing octahedral tilt angles range from 15-55°. There are three shorter (2.51 Å) and one longer (2.63 Å) Al(1)-Ge(1) bond length. Ge(1) is bonded to three equivalent Mg(1) and four equivalent Al(1) atoms to form a mixture of distorted edge and corner-sharing GeMg3Al4 pentagonal bipyramids.