MgTi4(CuS4)2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded in a 4-coordinate geometry to one Cu(2), one S(3), one S(6), and two equivalent S(4) atoms. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one S(1), one S(2), one S(3), one S(4), one S(5), and one S(6) atom to form TiS6 octahedra that share corners with three equivalent Cu(1)S4 tetrahedra and edges with two equivalent Ti(1)S6 octahedra. In the second Ti site, Ti(2) is bonded in a 5-coordinate geometry to one S(1), two equivalent S(2), and two equivalent S(4) atoms. In the third Ti site, Ti(3) is bonded in a 5-coordinate geometry to one S(5), two equivalent S(2), and two equivalent S(4) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one S(1), one S(5), and two equivalent S(4) atoms to form CuS4 tetrahedra that share corners with six equivalent Ti(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 51-57°. In the second Cu site, Cu(2) is bonded in a 5-coordinate geometry to one Mg(1), one S(3), one S(6), and two equivalent S(2) atoms. There are six inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Ti(2), two equivalent Ti(1), and one Cu(1) atom. In the second S site, S(2) is bonded to one Ti(1), one Ti(2), one Ti(3), and one Cu(2) atom to form a mixture of corner and edge-sharing STi3Cu tetrahedra. In the third S site, S(3) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Ti(1), and one Cu(2) atom. In the fourth S site, S(4) is bonded in a 5-coordinate geometry to one Mg(1), one Ti(1), one Ti(2), one Ti(3), and one Cu(1) atom. In the fifth S site, S(5) is bonded in a rectangular see-saw-like geometry to one Ti(3), two equivalent Ti(1), and one Cu(1) atom. In the sixth S site, S(6) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Ti(1), and one Cu(2) atom.
MgTi4(CuS4)2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded in a 4-coordinate geometry to one Cu(2), one S(3), one S(6), and two equivalent S(4) atoms. The Mg(1)-Cu(2) bond length is 2.65 Å. The Mg(1)-S(3) bond length is 2.33 Å. The Mg(1)-S(6) bond length is 2.33 Å. Both Mg(1)-S(4) bond lengths are 2.46 Å. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one S(1), one S(2), one S(3), one S(4), one S(5), and one S(6) atom to form TiS6 octahedra that share corners with three equivalent Cu(1)S4 tetrahedra and edges with two equivalent Ti(1)S6 octahedra. The Ti(1)-S(1) bond length is 2.44 Å. The Ti(1)-S(2) bond length is 2.63 Å. The Ti(1)-S(3) bond length is 2.51 Å. The Ti(1)-S(4) bond length is 2.47 Å. The Ti(1)-S(5) bond length is 2.44 Å. The Ti(1)-S(6) bond length is 2.51 Å. In the second Ti site, Ti(2) is bonded in a 5-coordinate geometry to one S(1), two equivalent S(2), and two equivalent S(4) atoms. The Ti(2)-S(1) bond length is 2.35 Å. Both Ti(2)-S(2) bond lengths are 2.43 Å. Both Ti(2)-S(4) bond lengths are 2.55 Å. In the third Ti site, Ti(3) is bonded in a 5-coordinate geometry to one S(5), two equivalent S(2), and two equivalent S(4) atoms. The Ti(3)-S(5) bond length is 2.35 Å. Both Ti(3)-S(2) bond lengths are 2.43 Å. Both Ti(3)-S(4) bond lengths are 2.55 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one S(1), one S(5), and two equivalent S(4) atoms to form CuS4 tetrahedra that share corners with six equivalent Ti(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 51-57°. The Cu(1)-S(1) bond length is 2.30 Å. The Cu(1)-S(5) bond length is 2.29 Å. Both Cu(1)-S(4) bond lengths are 2.30 Å. In the second Cu site, Cu(2) is bonded in a 5-coordinate geometry to one Mg(1), one S(3), one S(6), and two equivalent S(2) atoms. The Cu(2)-S(3) bond length is 2.45 Å. The Cu(2)-S(6) bond length is 2.45 Å. Both Cu(2)-S(2) bond lengths are 2.25 Å. There are six inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to one Ti(2), two equivalent Ti(1), and one Cu(1) atom. In the second S site, S(2) is bonded to one Ti(1), one Ti(2), one Ti(3), and one Cu(2) atom to form a mixture of corner and edge-sharing STi3Cu tetrahedra. In the third S site, S(3) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Ti(1), and one Cu(2) atom. In the fourth S site, S(4) is bonded in a 5-coordinate geometry to one Mg(1), one Ti(1), one Ti(2), one Ti(3), and one Cu(1) atom. In the fifth S site, S(5) is bonded in a rectangular see-saw-like geometry to one Ti(3), two equivalent Ti(1), and one Cu(1) atom. In the sixth S site, S(6) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Ti(1), and one Cu(2) atom.