Rb4MgTi2(CuS2)4 crystallizes in the monoclinic Cm space group. There are three inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a body-centered cubic geometry to four equivalent S(4) and four equivalent S(5) atoms. In the second Rb site, Rb(2) is bonded in a body-centered cubic geometry to two equivalent S(1), two equivalent S(2), two equivalent S(3), and two equivalent S(6) atoms. In the third Rb site, Rb(3) is bonded in a body-centered cubic geometry to four equivalent S(4) and four equivalent S(5) atoms. Mg(1) is bonded to one S(1), one S(2), and two equivalent S(5) atoms to form distorted MgS4 tetrahedra that share corners with four equivalent Ti(1)S4 tetrahedra. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one S(1), one S(2), and two equivalent S(5) atoms to form distorted TiS4 tetrahedra that share corners with four equivalent Mg(1)S4 tetrahedra. In the second Ti site, Ti(2) is bonded to one S(3), one S(6), and two equivalent S(4) atoms to form TiS4 tetrahedra that share edges with four equivalent Cu(2)S4 tetrahedra. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 4-coordinate geometry to one S(1), one S(2), and two equivalent S(5) atoms. In the second Cu site, Cu(2) is bonded to one S(3), one S(6), and two equivalent S(4) atoms to form distorted CuS4 tetrahedra that share corners with four equivalent Cu(2)S4 tetrahedra and edges with two equivalent Ti(2)S4 tetrahedra. There are six inequivalent S sites. In the first S site, S(1) is bonded in a 8-coordinate geometry to four equivalent Rb(2), one Mg(1), one Ti(1), and two equivalent Cu(1) atoms. In the second S site, S(2) is bonded in a 8-coordinate geometry to four equivalent Rb(2), one Mg(1), one Ti(1), and two equivalent Cu(1) atoms. In the third S site, S(3) is bonded in a 7-coordinate geometry to four equivalent Rb(2), one Ti(2), and two equivalent Cu(2) atoms. In the fourth S site, S(4) is bonded in a 7-coordinate geometry to two equivalent Rb(1), two equivalent Rb(3), one Ti(2), and two equivalent Cu(2) atoms. In the fifth S site, S(5) is bonded in a 8-coordinate geometry to two equivalent Rb(1), two equivalent Rb(3), one Mg(1), one Ti(1), and two equivalent Cu(1) atoms. In the sixth S site, S(6) is bonded in a 7-coordinate geometry to four equivalent Rb(2), one Ti(2), and two equivalent Cu(2) atoms.
Rb4MgTi2(CuS2)4 crystallizes in the monoclinic Cm space group. There are three inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a body-centered cubic geometry to four equivalent S(4) and four equivalent S(5) atoms. There are two shorter (3.46 Å) and two longer (3.51 Å) Rb(1)-S(4) bond lengths. There are two shorter (3.54 Å) and two longer (3.55 Å) Rb(1)-S(5) bond lengths. In the second Rb site, Rb(2) is bonded in a body-centered cubic geometry to two equivalent S(1), two equivalent S(2), two equivalent S(3), and two equivalent S(6) atoms. There is one shorter (3.57 Å) and one longer (3.62 Å) Rb(2)-S(1) bond length. Both Rb(2)-S(2) bond lengths are 3.53 Å. There is one shorter (3.44 Å) and one longer (3.52 Å) Rb(2)-S(3) bond length. There is one shorter (3.46 Å) and one longer (3.51 Å) Rb(2)-S(6) bond length. In the third Rb site, Rb(3) is bonded in a body-centered cubic geometry to four equivalent S(4) and four equivalent S(5) atoms. There are two shorter (3.44 Å) and two longer (3.51 Å) Rb(3)-S(4) bond lengths. There are two shorter (3.52 Å) and two longer (3.61 Å) Rb(3)-S(5) bond lengths. Mg(1) is bonded to one S(1), one S(2), and two equivalent S(5) atoms to form distorted MgS4 tetrahedra that share corners with four equivalent Ti(1)S4 tetrahedra. The Mg(1)-S(1) bond length is 2.47 Å. The Mg(1)-S(2) bond length is 2.45 Å. Both Mg(1)-S(5) bond lengths are 2.46 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one S(1), one S(2), and two equivalent S(5) atoms to form distorted TiS4 tetrahedra that share corners with four equivalent Mg(1)S4 tetrahedra. The Ti(1)-S(1) bond length is 2.44 Å. The Ti(1)-S(2) bond length is 2.42 Å. Both Ti(1)-S(5) bond lengths are 2.43 Å. In the second Ti site, Ti(2) is bonded to one S(3), one S(6), and two equivalent S(4) atoms to form TiS4 tetrahedra that share edges with four equivalent Cu(2)S4 tetrahedra. The Ti(2)-S(3) bond length is 2.29 Å. The Ti(2)-S(6) bond length is 2.29 Å. Both Ti(2)-S(4) bond lengths are 2.29 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a 4-coordinate geometry to one S(1), one S(2), and two equivalent S(5) atoms. The Cu(1)-S(1) bond length is 2.41 Å. The Cu(1)-S(2) bond length is 2.52 Å. There is one shorter (2.39 Å) and one longer (2.46 Å) Cu(1)-S(5) bond length. In the second Cu site, Cu(2) is bonded to one S(3), one S(6), and two equivalent S(4) atoms to form distorted CuS4 tetrahedra that share corners with four equivalent Cu(2)S4 tetrahedra and edges with two equivalent Ti(2)S4 tetrahedra. The Cu(2)-S(3) bond length is 2.38 Å. The Cu(2)-S(6) bond length is 2.38 Å. Both Cu(2)-S(4) bond lengths are 2.38 Å. There are six inequivalent S sites. In the first S site, S(1) is bonded in a 8-coordinate geometry to four equivalent Rb(2), one Mg(1), one Ti(1), and two equivalent Cu(1) atoms. In the second S site, S(2) is bonded in a 8-coordinate geometry to four equivalent Rb(2), one Mg(1), one Ti(1), and two equivalent Cu(1) atoms. In the third S site, S(3) is bonded in a 7-coordinate geometry to four equivalent Rb(2), one Ti(2), and two equivalent Cu(2) atoms. In the fourth S site, S(4) is bonded in a 7-coordinate geometry to two equivalent Rb(1), two equivalent Rb(3), one Ti(2), and two equivalent Cu(2) atoms. In the fifth S site, S(5) is bonded in a 8-coordinate geometry to two equivalent Rb(1), two equivalent Rb(3), one Mg(1), one Ti(1), and two equivalent Cu(1) atoms. In the sixth S site, S(6) is bonded in a 7-coordinate geometry to four equivalent Rb(2), one Ti(2), and two equivalent Cu(2) atoms.