Cs2Mg(FeS2)2 crystallizes in the monoclinic Cm space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a distorted see-saw-like geometry to two equivalent S(3) and two equivalent S(4) atoms. In the second Cs site, Cs(2) is bonded in a 8-coordinate geometry to two equivalent Mg(1), one S(1), one S(2), two equivalent S(3), and two equivalent S(4) atoms. Mg(1) is bonded in a distorted trigonal planar geometry to two equivalent Cs(2), one S(1), one S(2), and one S(4) atom. Fe(1) is bonded to one S(1), one S(2), one S(3), and one S(4) atom to form edge-sharing FeS4 tetrahedra. There are four inequivalent S sites. In the first S site, S(1) is bonded in a 3-coordinate geometry to one Cs(2), one Mg(1), and two equivalent Fe(1) atoms. In the second S site, S(2) is bonded in a 3-coordinate geometry to one Cs(2), one Mg(1), and two equivalent Fe(1) atoms. In the third S site, S(3) is bonded in a 6-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Fe(1) atoms. In the fourth S site, S(4) is bonded to two equivalent Cs(1), two equivalent Cs(2), one Mg(1), and two equivalent Fe(1) atoms to form distorted corner-sharing SCs4MgFe2 pentagonal bipyramids.
Cs2Mg(FeS2)2 crystallizes in the monoclinic Cm space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a distorted see-saw-like geometry to two equivalent S(3) and two equivalent S(4) atoms. Both Cs(1)-S(3) bond lengths are 3.62 Å. There is one shorter (3.64 Å) and one longer (3.65 Å) Cs(1)-S(4) bond length. In the second Cs site, Cs(2) is bonded in a 8-coordinate geometry to two equivalent Mg(1), one S(1), one S(2), two equivalent S(3), and two equivalent S(4) atoms. Both Cs(2)-Mg(1) bond lengths are 3.30 Å. The Cs(2)-S(1) bond length is 3.59 Å. The Cs(2)-S(2) bond length is 3.63 Å. There is one shorter (3.68 Å) and one longer (3.71 Å) Cs(2)-S(3) bond length. Both Cs(2)-S(4) bond lengths are 3.40 Å. Mg(1) is bonded in a distorted trigonal planar geometry to two equivalent Cs(2), one S(1), one S(2), and one S(4) atom. The Mg(1)-S(1) bond length is 2.36 Å. The Mg(1)-S(2) bond length is 2.36 Å. The Mg(1)-S(4) bond length is 2.46 Å. Fe(1) is bonded to one S(1), one S(2), one S(3), and one S(4) atom to form edge-sharing FeS4 tetrahedra. The Fe(1)-S(1) bond length is 2.37 Å. The Fe(1)-S(2) bond length is 2.37 Å. The Fe(1)-S(3) bond length is 2.27 Å. The Fe(1)-S(4) bond length is 2.39 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded in a 3-coordinate geometry to one Cs(2), one Mg(1), and two equivalent Fe(1) atoms. In the second S site, S(2) is bonded in a 3-coordinate geometry to one Cs(2), one Mg(1), and two equivalent Fe(1) atoms. In the third S site, S(3) is bonded in a 6-coordinate geometry to two equivalent Cs(1), two equivalent Cs(2), and two equivalent Fe(1) atoms. In the fourth S site, S(4) is bonded to two equivalent Cs(1), two equivalent Cs(2), one Mg(1), and two equivalent Fe(1) atoms to form distorted corner-sharing SCs4MgFe2 pentagonal bipyramids.