K2Cd3S4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to one S(2), one S(3), and four equivalent S(1) atoms to form distorted KS6 octahedra that share corners with four equivalent Cd(2)S4 tetrahedra, corners with eight equivalent Cd(1)S4 tetrahedra, edges with two equivalent K(1)S6 octahedra, edges with four equivalent K(2)S6 octahedra,  an edgeedge with one Cd(2)S4 tetrahedra, and edges with two equivalent Cd(1)S4 tetrahedra. In the second K site, K(2) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form distorted KS6 octahedra that share corners with two equivalent Cd(2)S4 tetrahedra, corners with eight equivalent Cd(1)S4 tetrahedra, edges with two equivalent K(2)S6 octahedra, edges with four equivalent K(1)S6 octahedra, edges with two equivalent Cd(1)S4 tetrahedra, and edges with two equivalent Cd(2)S4 tetrahedra. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form distorted CdS4 tetrahedra that share corners with four equivalent K(1)S6 octahedra, corners with four equivalent K(2)S6 octahedra, corners with two equivalent Cd(1)S4 tetrahedra, corners with two equivalent Cd(2)S4 tetrahedra,  an edgeedge with one K(1)S6 octahedra,  an edgeedge with one K(2)S6 octahedra,  an edgeedge with one Cd(1)S4 tetrahedra, and  an edgeedge with one Cd(2)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 9-92°. In the second Cd site, Cd(2) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form distorted CdS4 tetrahedra that share corners with two equivalent K(2)S6 octahedra, corners with four equivalent K(1)S6 octahedra, corners with four equivalent Cd(1)S4 tetrahedra,  an edgeedge with one K(1)S6 octahedra, edges with two equivalent K(2)S6 octahedra, and edges with two equivalent Cd(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 12-96°. There are three inequivalent S sites. In the first S site, S(3) is bonded to one K(1), two equivalent K(2), one Cd(2), and two equivalent Cd(1) atoms to form a mixture of distorted corner and edge-sharing SK3Cd3 octahedra. The corner-sharing octahedral tilt angles range from 0-69°. In the second S site, S(1) is bonded to one K(2), two equivalent K(1), one Cd(2), and two equivalent Cd(1) atoms to form a mixture of distorted corner and edge-sharing SK3Cd3 octahedra. The corner-sharing octahedral tilt angles range from 0-69°. In the third S site, S(2) is bonded to one K(1), two equivalent K(2), one Cd(2), and two equivalent Cd(1) atoms to form a mixture of distorted corner and edge-sharing SK3Cd3 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 19-90°.
K2Cd3S4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to one S(2), one S(3), and four equivalent S(1) atoms to form distorted KS6 octahedra that share corners with four equivalent Cd(2)S4 tetrahedra, corners with eight equivalent Cd(1)S4 tetrahedra, edges with two equivalent K(1)S6 octahedra, edges with four equivalent K(2)S6 octahedra,  an edgeedge with one Cd(2)S4 tetrahedra, and edges with two equivalent Cd(1)S4 tetrahedra. The K(1)-S(2) bond length is 3.33 Å. The K(1)-S(3) bond length is 3.37 Å. There are two shorter (3.32 Å) and two longer (3.35 Å) K(1)-S(1) bond lengths. In the second K site, K(2) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form distorted KS6 octahedra that share corners with two equivalent Cd(2)S4 tetrahedra, corners with eight equivalent Cd(1)S4 tetrahedra, edges with two equivalent K(2)S6 octahedra, edges with four equivalent K(1)S6 octahedra, edges with two equivalent Cd(1)S4 tetrahedra, and edges with two equivalent Cd(2)S4 tetrahedra. Both K(2)-S(1) bond lengths are 3.15 Å. Both K(2)-S(2) bond lengths are 3.28 Å. Both K(2)-S(3) bond lengths are 3.39 Å. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form distorted CdS4 tetrahedra that share corners with four equivalent K(1)S6 octahedra, corners with four equivalent K(2)S6 octahedra, corners with two equivalent Cd(1)S4 tetrahedra, corners with two equivalent Cd(2)S4 tetrahedra,  an edgeedge with one K(1)S6 octahedra,  an edgeedge with one K(2)S6 octahedra,  an edgeedge with one Cd(1)S4 tetrahedra, and  an edgeedge with one Cd(2)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 9-92°. The Cd(1)-S(2) bond length is 2.68 Å. The Cd(1)-S(3) bond length is 2.60 Å. There is one shorter (2.51 Å) and one longer (2.55 Å) Cd(1)-S(1) bond length. In the second Cd site, Cd(2) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form distorted CdS4 tetrahedra that share corners with two equivalent K(2)S6 octahedra, corners with four equivalent K(1)S6 octahedra, corners with four equivalent Cd(1)S4 tetrahedra,  an edgeedge with one K(1)S6 octahedra, edges with two equivalent K(2)S6 octahedra, and edges with two equivalent Cd(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 12-96°. The Cd(2)-S(2) bond length is 2.56 Å. The Cd(2)-S(3) bond length is 2.50 Å. Both Cd(2)-S(1) bond lengths are 2.66 Å. There are three inequivalent S sites. In the first S site, S(3) is bonded to one K(1), two equivalent K(2), one Cd(2), and two equivalent Cd(1) atoms to form a mixture of distorted corner and edge-sharing SK3Cd3 octahedra. The corner-sharing octahedral tilt angles range from 0-69°. In the second S site, S(1) is bonded to one K(2), two equivalent K(1), one Cd(2), and two equivalent Cd(1) atoms to form a mixture of distorted corner and edge-sharing SK3Cd3 octahedra. The corner-sharing octahedral tilt angles range from 0-69°. In the third S site, S(2) is bonded to one K(1), two equivalent K(2), one Cd(2), and two equivalent Cd(1) atoms to form a mixture of distorted corner and edge-sharing SK3Cd3 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 19-90°.