K3Nd(AsS4)2 crystallizes in the monoclinic C2/c space group. There are three inequivalent K sites. In the first K site, K(1) is bonded in a distorted body-centered cubic geometry to four equivalent S(1) and four equivalent S(2) atoms. In the second K site, K(2) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(4), and four equivalent S(3) atoms. In the third K site, K(3) is bonded in a square co-planar geometry to four equivalent S(2) atoms. Nd(1) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(3), and four equivalent S(4) atoms. As(1) is bonded in a tetrahedral geometry to one S(1), one S(2), one S(3), and one S(4) atom. There are four inequivalent S sites. In the first S site, S(1) is bonded to one K(2), two equivalent K(1), one Nd(1), and one As(1) atom to form distorted SK3NdAs square pyramids that share corners with two equivalent S(1)K3NdAs square pyramids, corners with four equivalent S(2)K4As square pyramids,  an edgeedge with one S(2)K4As square pyramid, edges with three equivalent S(1)K3NdAs square pyramids, and  a faceface with one S(2)K4As square pyramid. In the second S site, S(2) is bonded to two equivalent K(1), two equivalent K(3), and one As(1) atom to form distorted SK4As square pyramids that share corners with four equivalent S(1)K3NdAs square pyramids, corners with four equivalent S(2)K4As square pyramids,  an edgeedge with one S(1)K3NdAs square pyramid, edges with four equivalent S(2)K4As square pyramids, and  a faceface with one S(1)K3NdAs square pyramid. In the third S site, S(3) is bonded in a distorted see-saw-like geometry to two equivalent K(2), one Nd(1), and one As(1) atom. In the fourth S site, S(4) is bonded in a 4-coordinate geometry to one K(2), two equivalent Nd(1), and one As(1) atom.
K3Nd(AsS4)2 crystallizes in the monoclinic C2/c space group. There are three inequivalent K sites. In the first K site, K(1) is bonded in a distorted body-centered cubic geometry to four equivalent S(1) and four equivalent S(2) atoms. There are two shorter (3.59 Å) and two longer (3.62 Å) K(1)-S(1) bond lengths. There are two shorter (3.26 Å) and two longer (3.36 Å) K(1)-S(2) bond lengths. In the second K site, K(2) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(4), and four equivalent S(3) atoms. Both K(2)-S(1) bond lengths are 3.26 Å. Both K(2)-S(4) bond lengths are 3.61 Å. There are two shorter (3.43 Å) and two longer (3.50 Å) K(2)-S(3) bond lengths. In the third K site, K(3) is bonded in a square co-planar geometry to four equivalent S(2) atoms. There are two shorter (3.18 Å) and two longer (3.34 Å) K(3)-S(2) bond lengths. Nd(1) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(3), and four equivalent S(4) atoms. Both Nd(1)-S(1) bond lengths are 2.89 Å. Both Nd(1)-S(3) bond lengths are 2.91 Å. There are two shorter (3.09 Å) and two longer (3.14 Å) Nd(1)-S(4) bond lengths. As(1) is bonded in a tetrahedral geometry to one S(1), one S(2), one S(3), and one S(4) atom. The As(1)-S(1) bond length is 2.20 Å. The As(1)-S(2) bond length is 2.16 Å. The As(1)-S(3) bond length is 2.20 Å. The As(1)-S(4) bond length is 2.20 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded to one K(2), two equivalent K(1), one Nd(1), and one As(1) atom to form distorted SK3NdAs square pyramids that share corners with two equivalent S(1)K3NdAs square pyramids, corners with four equivalent S(2)K4As square pyramids,  an edgeedge with one S(2)K4As square pyramid, edges with three equivalent S(1)K3NdAs square pyramids, and  a faceface with one S(2)K4As square pyramid. In the second S site, S(2) is bonded to two equivalent K(1), two equivalent K(3), and one As(1) atom to form distorted SK4As square pyramids that share corners with four equivalent S(1)K3NdAs square pyramids, corners with four equivalent S(2)K4As square pyramids,  an edgeedge with one S(1)K3NdAs square pyramid, edges with four equivalent S(2)K4As square pyramids, and  a faceface with one S(1)K3NdAs square pyramid. In the third S site, S(3) is bonded in a distorted see-saw-like geometry to two equivalent K(2), one Nd(1), and one As(1) atom. In the fourth S site, S(4) is bonded in a 4-coordinate geometry to one K(2), two equivalent Nd(1), and one As(1) atom.