K3Cr11S18 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one S(4), two equivalent S(1), two equivalent S(2), and three equivalent S(3) atoms. In the second K site, K(2) is bonded in a distorted body-centered cubic geometry to four equivalent S(7) and four equivalent S(8) atoms. There are six inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one S(3), one S(8), two equivalent S(4), and two equivalent S(6) atoms to form a mixture of edge and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles are 48°. In the second Cr site, Cr(2) is bonded to one S(4), two equivalent S(8), and three equivalent S(5) atoms to form a mixture of edge, face, and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles range from 47-52°. In the third Cr site, Cr(3) is bonded to one S(2), one S(6), two equivalent S(3), and two equivalent S(9) atoms to form a mixture of edge, face, and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles are 46°. In the fourth Cr site, Cr(4) is bonded to one S(1), one S(6), two equivalent S(7), and two equivalent S(9) atoms to form a mixture of edge, face, and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles range from 46-50°. In the fifth Cr site, Cr(5) is bonded to one S(4), one S(7), two equivalent S(1), and two equivalent S(5) atoms to form a mixture of edge, face, and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles range from 47-52°. In the sixth Cr site, Cr(6) is bonded to two equivalent S(9) and four equivalent S(2) atoms to form a mixture of edge and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are nine inequivalent S sites. In the first S site, S(5) is bonded to two equivalent Cr(5) and three equivalent Cr(2) atoms to form distorted SCr5 trigonal bipyramids that share  a cornercorner with one S(4)KCr4 trigonal bipyramid, edges with two equivalent S(4)KCr4 trigonal bipyramids, and edges with four equivalent S(5)Cr5 trigonal bipyramids. In the second S site, S(6) is bonded in a rectangular see-saw-like geometry to one Cr(3), one Cr(4), and two equivalent Cr(1) atoms. In the third S site, S(7) is bonded in a 5-coordinate geometry to two equivalent K(2), one Cr(5), and two equivalent Cr(4) atoms. In the fourth S site, S(8) is bonded in a 5-coordinate geometry to two equivalent K(2), one Cr(1), and two equivalent Cr(2) atoms. In the fifth S site, S(9) is bonded to one Cr(6), two equivalent Cr(3), and two equivalent Cr(4) atoms to form distorted SCr5 trigonal bipyramids that share corners with two equivalent S(3)K3Cr3 octahedra, corners with two equivalent S(2)K2Cr3 square pyramids,  a cornercorner with one S(9)Cr5 trigonal bipyramid,  an edgeedge with one S(3)K3Cr3 octahedra, edges with two equivalent S(2)K2Cr3 square pyramids, and edges with two equivalent S(9)Cr5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 6°. In the sixth S site, S(1) is bonded in a 5-coordinate geometry to two equivalent K(1), one Cr(4), and two equivalent Cr(5) atoms. In the seventh S site, S(2) is bonded to two equivalent K(1), one Cr(3), and two equivalent Cr(6) atoms to form distorted SK2Cr3 square pyramids that share corners with two equivalent S(3)K3Cr3 octahedra, corners with two equivalent S(2)K2Cr3 square pyramids, corners with two equivalent S(9)Cr5 trigonal bipyramids, corners with two equivalent S(4)KCr4 trigonal bipyramids, edges with three equivalent S(3)K3Cr3 octahedra, edges with three equivalent S(2)K2Cr3 square pyramids, and edges with two equivalent S(9)Cr5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 18°. In the eighth S site, S(3) is bonded to three equivalent K(1), one Cr(1), and two equivalent Cr(3) atoms to form distorted SK3Cr3 octahedra that share corners with two equivalent S(2)K2Cr3 square pyramids,  a cornercorner with one S(4)KCr4 trigonal bipyramid, corners with two equivalent S(9)Cr5 trigonal bipyramids, edges with four equivalent S(3)K3Cr3 octahedra, edges with three equivalent S(2)K2Cr3 square pyramids,  an edgeedge with one S(9)Cr5 trigonal bipyramid, and edges with two equivalent S(4)KCr4 trigonal bipyramids. In the ninth S site, S(4) is bonded to one K(1), one Cr(2), one Cr(5), and two equivalent Cr(1) atoms to form distorted SKCr4 trigonal bipyramids that share  a cornercorner with one S(3)K3Cr3 octahedra, corners with two equivalent S(2)K2Cr3 square pyramids,  a cornercorner with one S(5)Cr5 trigonal bipyramid, corners with two equivalent S(4)KCr4 trigonal bipyramids, edges with two equivalent S(3)K3Cr3 octahedra, and edges with two equivalent S(5)Cr5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 20°.
K3Cr11S18 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one S(4), two equivalent S(1), two equivalent S(2), and three equivalent S(3) atoms. The K(1)-S(4) bond length is 3.30 Å. Both K(1)-S(1) bond lengths are 3.25 Å. Both K(1)-S(2) bond lengths are 3.16 Å. There are two shorter (3.37 Å) and one longer (3.56 Å) K(1)-S(3) bond length. In the second K site, K(2) is bonded in a distorted body-centered cubic geometry to four equivalent S(7) and four equivalent S(8) atoms. All K(2)-S(7) bond lengths are 3.48 Å. All K(2)-S(8) bond lengths are 3.37 Å. There are six inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one S(3), one S(8), two equivalent S(4), and two equivalent S(6) atoms to form a mixture of edge and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles are 48°. The Cr(1)-S(3) bond length is 2.48 Å. The Cr(1)-S(8) bond length is 2.42 Å. Both Cr(1)-S(4) bond lengths are 2.39 Å. Both Cr(1)-S(6) bond lengths are 2.37 Å. In the second Cr site, Cr(2) is bonded to one S(4), two equivalent S(8), and three equivalent S(5) atoms to form a mixture of edge, face, and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles range from 47-52°. The Cr(2)-S(4) bond length is 2.38 Å. Both Cr(2)-S(8) bond lengths are 2.35 Å. There is one shorter (2.41 Å) and two longer (2.55 Å) Cr(2)-S(5) bond lengths. In the third Cr site, Cr(3) is bonded to one S(2), one S(6), two equivalent S(3), and two equivalent S(9) atoms to form a mixture of edge, face, and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles are 46°. The Cr(3)-S(2) bond length is 2.36 Å. The Cr(3)-S(6) bond length is 2.41 Å. Both Cr(3)-S(3) bond lengths are 2.39 Å. Both Cr(3)-S(9) bond lengths are 2.53 Å. In the fourth Cr site, Cr(4) is bonded to one S(1), one S(6), two equivalent S(7), and two equivalent S(9) atoms to form a mixture of edge, face, and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles range from 46-50°. The Cr(4)-S(1) bond length is 2.35 Å. The Cr(4)-S(6) bond length is 2.41 Å. Both Cr(4)-S(7) bond lengths are 2.38 Å. Both Cr(4)-S(9) bond lengths are 2.52 Å. In the fifth Cr site, Cr(5) is bonded to one S(4), one S(7), two equivalent S(1), and two equivalent S(5) atoms to form a mixture of edge, face, and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles range from 47-52°. The Cr(5)-S(4) bond length is 2.45 Å. The Cr(5)-S(7) bond length is 2.37 Å. Both Cr(5)-S(1) bond lengths are 2.35 Å. Both Cr(5)-S(5) bond lengths are 2.51 Å. In the sixth Cr site, Cr(6) is bonded to two equivalent S(9) and four equivalent S(2) atoms to form a mixture of edge and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles are 50°. Both Cr(6)-S(9) bond lengths are 2.44 Å. All Cr(6)-S(2) bond lengths are 2.42 Å. There are nine inequivalent S sites. In the first S site, S(5) is bonded to two equivalent Cr(5) and three equivalent Cr(2) atoms to form distorted SCr5 trigonal bipyramids that share  a cornercorner with one S(4)KCr4 trigonal bipyramid, edges with two equivalent S(4)KCr4 trigonal bipyramids, and edges with four equivalent S(5)Cr5 trigonal bipyramids. In the second S site, S(6) is bonded in a rectangular see-saw-like geometry to one Cr(3), one Cr(4), and two equivalent Cr(1) atoms. In the third S site, S(7) is bonded in a 5-coordinate geometry to two equivalent K(2), one Cr(5), and two equivalent Cr(4) atoms. In the fourth S site, S(8) is bonded in a 5-coordinate geometry to two equivalent K(2), one Cr(1), and two equivalent Cr(2) atoms. In the fifth S site, S(9) is bonded to one Cr(6), two equivalent Cr(3), and two equivalent Cr(4) atoms to form distorted SCr5 trigonal bipyramids that share corners with two equivalent S(3)K3Cr3 octahedra, corners with two equivalent S(2)K2Cr3 square pyramids,  a cornercorner with one S(9)Cr5 trigonal bipyramid,  an edgeedge with one S(3)K3Cr3 octahedra, edges with two equivalent S(2)K2Cr3 square pyramids, and edges with two equivalent S(9)Cr5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 6°. In the sixth S site, S(1) is bonded in a 5-coordinate geometry to two equivalent K(1), one Cr(4), and two equivalent Cr(5) atoms. In the seventh S site, S(2) is bonded to two equivalent K(1), one Cr(3), and two equivalent Cr(6) atoms to form distorted SK2Cr3 square pyramids that share corners with two equivalent S(3)K3Cr3 octahedra, corners with two equivalent S(2)K2Cr3 square pyramids, corners with two equivalent S(9)Cr5 trigonal bipyramids, corners with two equivalent S(4)KCr4 trigonal bipyramids, edges with three equivalent S(3)K3Cr3 octahedra, edges with three equivalent S(2)K2Cr3 square pyramids, and edges with two equivalent S(9)Cr5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 18°. In the eighth S site, S(3) is bonded to three equivalent K(1), one Cr(1), and two equivalent Cr(3) atoms to form distorted SK3Cr3 octahedra that share corners with two equivalent S(2)K2Cr3 square pyramids,  a cornercorner with one S(4)KCr4 trigonal bipyramid, corners with two equivalent S(9)Cr5 trigonal bipyramids, edges with four equivalent S(3)K3Cr3 octahedra, edges with three equivalent S(2)K2Cr3 square pyramids,  an edgeedge with one S(9)Cr5 trigonal bipyramid, and edges with two equivalent S(4)KCr4 trigonal bipyramids. In the ninth S site, S(4) is bonded to one K(1), one Cr(2), one Cr(5), and two equivalent Cr(1) atoms to form distorted SKCr4 trigonal bipyramids that share  a cornercorner with one S(3)K3Cr3 octahedra, corners with two equivalent S(2)K2Cr3 square pyramids,  a cornercorner with one S(5)Cr5 trigonal bipyramid, corners with two equivalent S(4)KCr4 trigonal bipyramids, edges with two equivalent S(3)K3Cr3 octahedra, and edges with two equivalent S(5)Cr5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 20°.