MgCu3AsS4 crystallizes in the cubic P-43m space group. Mg(1) is bonded to six equivalent Cu(1) and four equivalent S(1) atoms to form distorted MgCu6S4 tetrahedra that share corners with four equivalent As(1)S4 tetrahedra, corners with six equivalent Mg(1)Cu6S4 tetrahedra, and edges with six equivalent Cu(1)Mg2S4 tetrahedra. Cu(1) is bonded to two equivalent Mg(1) and four equivalent S(1) atoms to form distorted CuMg2S4 tetrahedra that share corners with two equivalent Cu(1)Mg2S4 tetrahedra, corners with four equivalent As(1)S4 tetrahedra, edges with two equivalent Mg(1)Cu6S4 tetrahedra, and edges with eight equivalent Cu(1)Mg2S4 tetrahedra. As(1) is bonded to four equivalent S(1) atoms to form AsS4 tetrahedra that share corners with four equivalent Mg(1)Cu6S4 tetrahedra and corners with twelve equivalent Cu(1)Mg2S4 tetrahedra. S(1) is bonded in a distorted pentagonal planar geometry to one Mg(1), three equivalent Cu(1), and one As(1) atom.
MgCu3AsS4 crystallizes in the cubic P-43m space group. Mg(1) is bonded to six equivalent Cu(1) and four equivalent S(1) atoms to form distorted MgCu6S4 tetrahedra that share corners with four equivalent As(1)S4 tetrahedra, corners with six equivalent Mg(1)Cu6S4 tetrahedra, and edges with six equivalent Cu(1)Mg2S4 tetrahedra. All Mg(1)-Cu(1) bond lengths are 2.80 Å. All Mg(1)-S(1) bond lengths are 2.39 Å. Cu(1) is bonded to two equivalent Mg(1) and four equivalent S(1) atoms to form distorted CuMg2S4 tetrahedra that share corners with two equivalent Cu(1)Mg2S4 tetrahedra, corners with four equivalent As(1)S4 tetrahedra, edges with two equivalent Mg(1)Cu6S4 tetrahedra, and edges with eight equivalent Cu(1)Mg2S4 tetrahedra. All Cu(1)-S(1) bond lengths are 2.41 Å. As(1) is bonded to four equivalent S(1) atoms to form AsS4 tetrahedra that share corners with four equivalent Mg(1)Cu6S4 tetrahedra and corners with twelve equivalent Cu(1)Mg2S4 tetrahedra. All As(1)-S(1) bond lengths are 2.46 Å. S(1) is bonded in a distorted pentagonal planar geometry to one Mg(1), three equivalent Cu(1), and one As(1) atom.