K6Mg(SbS4)2 crystallizes in the monoclinic Cm space group. There are four inequivalent K sites. In the first K site, K(1) is bonded to one S(1), one S(2), one S(4), and two equivalent S(6) atoms to form distorted KS5 trigonal bipyramids that share  a cornercorner with one Mg(1)S4 tetrahedra and edges with two equivalent Sb(1)S4 tetrahedra. In the second K site, K(2) is bonded in a 2-coordinate geometry to one S(2), one S(3), and two equivalent S(5) atoms. In the third K site, K(3) is bonded in a 4-coordinate geometry to one S(2), one S(3), one S(5), and two equivalent S(6) atoms. In the fourth K site, K(4) is bonded in a distorted rectangular see-saw-like geometry to one S(1), one S(4), and two equivalent S(5) atoms. Mg(1) is bonded to one S(3), one S(4), and two equivalent S(5) atoms to form MgS4 tetrahedra that share  a cornercorner with one Sb(1)S4 tetrahedra and  a cornercorner with one K(1)S5 trigonal bipyramid. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to one S(2), one S(4), and two equivalent S(6) atoms to form SbS4 tetrahedra that share  a cornercorner with one Mg(1)S4 tetrahedra and edges with two equivalent K(1)S5 trigonal bipyramids. In the second Sb site, Sb(2) is bonded in a distorted trigonal non-coplanar geometry to one S(1) and two equivalent S(5) atoms. There are six inequivalent S sites. In the first S site, S(1) is bonded in a 4-coordinate geometry to one K(1), two equivalent K(4), and one Sb(2) atom. In the second S site, S(2) is bonded to one K(1), one K(2), two equivalent K(3), and one Sb(1) atom to form distorted edge-sharing SK4Sb trigonal bipyramids. In the third S site, S(3) is bonded in a 4-coordinate geometry to one K(2), two equivalent K(3), and one Mg(1) atom. In the fourth S site, S(4) is bonded to one K(1), two equivalent K(4), one Mg(1), and one Sb(1) atom to form distorted edge-sharing SK3MgSb trigonal bipyramids. In the fifth S site, S(5) is bonded in a 6-coordinate geometry to one K(2), one K(3), two equivalent K(4), one Mg(1), and one Sb(2) atom. In the sixth S site, S(6) is bonded in a rectangular see-saw-like geometry to one K(1), two equivalent K(3), and one Sb(1) atom.
K6Mg(SbS4)2 crystallizes in the monoclinic Cm space group. There are four inequivalent K sites. In the first K site, K(1) is bonded to one S(1), one S(2), one S(4), and two equivalent S(6) atoms to form distorted KS5 trigonal bipyramids that share  a cornercorner with one Mg(1)S4 tetrahedra and edges with two equivalent Sb(1)S4 tetrahedra. The K(1)-S(1) bond length is 3.27 Å. The K(1)-S(2) bond length is 3.19 Å. The K(1)-S(4) bond length is 3.34 Å. Both K(1)-S(6) bond lengths are 3.33 Å. In the second K site, K(2) is bonded in a 2-coordinate geometry to one S(2), one S(3), and two equivalent S(5) atoms. The K(2)-S(2) bond length is 3.24 Å. The K(2)-S(3) bond length is 3.06 Å. Both K(2)-S(5) bond lengths are 3.68 Å. In the third K site, K(3) is bonded in a 4-coordinate geometry to one S(2), one S(3), one S(5), and two equivalent S(6) atoms. The K(3)-S(2) bond length is 3.19 Å. The K(3)-S(3) bond length is 3.03 Å. The K(3)-S(5) bond length is 3.68 Å. There is one shorter (3.16 Å) and one longer (3.34 Å) K(3)-S(6) bond length. In the fourth K site, K(4) is bonded in a distorted rectangular see-saw-like geometry to one S(1), one S(4), and two equivalent S(5) atoms. The K(4)-S(1) bond length is 3.21 Å. The K(4)-S(4) bond length is 3.17 Å. There is one shorter (3.29 Å) and one longer (3.41 Å) K(4)-S(5) bond length. Mg(1) is bonded to one S(3), one S(4), and two equivalent S(5) atoms to form MgS4 tetrahedra that share  a cornercorner with one Sb(1)S4 tetrahedra and  a cornercorner with one K(1)S5 trigonal bipyramid. The Mg(1)-S(3) bond length is 2.35 Å. The Mg(1)-S(4) bond length is 2.50 Å. Both Mg(1)-S(5) bond lengths are 2.52 Å. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to one S(2), one S(4), and two equivalent S(6) atoms to form SbS4 tetrahedra that share  a cornercorner with one Mg(1)S4 tetrahedra and edges with two equivalent K(1)S5 trigonal bipyramids. The Sb(1)-S(2) bond length is 2.39 Å. The Sb(1)-S(4) bond length is 2.42 Å. Both Sb(1)-S(6) bond lengths are 2.36 Å. In the second Sb site, Sb(2) is bonded in a distorted trigonal non-coplanar geometry to one S(1) and two equivalent S(5) atoms. The Sb(2)-S(1) bond length is 2.47 Å. Both Sb(2)-S(5) bond lengths are 2.52 Å. There are six inequivalent S sites. In the first S site, S(1) is bonded in a 4-coordinate geometry to one K(1), two equivalent K(4), and one Sb(2) atom. In the second S site, S(2) is bonded to one K(1), one K(2), two equivalent K(3), and one Sb(1) atom to form distorted edge-sharing SK4Sb trigonal bipyramids. In the third S site, S(3) is bonded in a 4-coordinate geometry to one K(2), two equivalent K(3), and one Mg(1) atom. In the fourth S site, S(4) is bonded to one K(1), two equivalent K(4), one Mg(1), and one Sb(1) atom to form distorted edge-sharing SK3MgSb trigonal bipyramids. In the fifth S site, S(5) is bonded in a 6-coordinate geometry to one K(2), one K(3), two equivalent K(4), one Mg(1), and one Sb(2) atom. In the sixth S site, S(6) is bonded in a rectangular see-saw-like geometry to one K(1), two equivalent K(3), and one Sb(1) atom.