U3ScS6 crystallizes in the orthorhombic Pnnm space group. There are three inequivalent U sites. In the first U site, U(1) is bonded in a 8-coordinate geometry to one S(1), one S(5), two equivalent S(2), two equivalent S(3), and two equivalent S(6) atoms. In the second U site, U(2) is bonded in a 8-coordinate geometry to one S(3), one S(5), two equivalent S(1), two equivalent S(4), and two equivalent S(6) atoms. In the third U site, U(3) is bonded to one S(2), one S(5), one S(6), two equivalent S(3), and two equivalent S(4) atoms to form distorted US7 pentagonal bipyramids that share  a cornercorner with one Sc(1)S6 octahedra, edges with two equivalent Sc(2)S6 octahedra, and edges with two equivalent U(3)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 32°. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form ScS6 octahedra that share corners with two equivalent U(3)S7 pentagonal bipyramids and edges with two equivalent Sc(1)S6 octahedra. In the second Sc site, Sc(2) is bonded to two equivalent S(4) and four equivalent S(5) atoms to form ScS6 octahedra that share edges with two equivalent Sc(2)S6 octahedra and edges with four equivalent U(3)S7 pentagonal bipyramids. There are six inequivalent S sites. In the first S site, S(5) is bonded to one U(1), one U(2), one U(3), and two equivalent Sc(2) atoms to form distorted SSc2U3 trigonal bipyramids that share  a cornercorner with one S(6)U5 trigonal bipyramid, corners with three equivalent S(1)Sc2U3 trigonal bipyramids, corners with four equivalent S(5)Sc2U3 trigonal bipyramids, corners with three equivalent S(2)ScU3 trigonal pyramids, edges with four equivalent S(4)ScU4 square pyramids,  an edgeedge with one S(5)Sc2U3 trigonal bipyramid, and edges with two equivalent S(6)U5 trigonal bipyramids. In the second S site, S(6) is bonded to one U(3), two equivalent U(1), and two equivalent U(2) atoms to form distorted SU5 trigonal bipyramids that share corners with four equivalent S(4)ScU4 square pyramids,  a cornercorner with one S(5)Sc2U3 trigonal bipyramid, corners with four equivalent S(1)Sc2U3 trigonal bipyramids, corners with two equivalent S(2)ScU3 trigonal pyramids,  an edgeedge with one S(4)ScU4 square pyramid,  an edgeedge with one S(1)Sc2U3 trigonal bipyramid, edges with two equivalent S(5)Sc2U3 trigonal bipyramids, edges with two equivalent S(6)U5 trigonal bipyramids, and  a faceface with one S(2)ScU3 trigonal pyramid. In the third S site, S(1) is bonded to one U(1), two equivalent U(2), and two equivalent Sc(1) atoms to form distorted SSc2U3 trigonal bipyramids that share corners with two equivalent S(4)ScU4 square pyramids, corners with two equivalent S(1)Sc2U3 trigonal bipyramids, corners with three equivalent S(5)Sc2U3 trigonal bipyramids, corners with four equivalent S(6)U5 trigonal bipyramids, corners with two equivalent S(2)ScU3 trigonal pyramids,  an edgeedge with one S(4)ScU4 square pyramid,  an edgeedge with one S(6)U5 trigonal bipyramid, edges with three equivalent S(1)Sc2U3 trigonal bipyramids, and edges with two equivalent S(2)ScU3 trigonal pyramids. In the fourth S site, S(2) is bonded to one U(3), two equivalent U(1), and one Sc(1) atom to form distorted SScU3 trigonal pyramids that share corners with two equivalent S(4)ScU4 square pyramids, corners with two equivalent S(1)Sc2U3 trigonal bipyramids, corners with two equivalent S(6)U5 trigonal bipyramids, corners with three equivalent S(5)Sc2U3 trigonal bipyramids, corners with three equivalent S(2)ScU3 trigonal pyramids, edges with two equivalent S(1)Sc2U3 trigonal bipyramids, and  a faceface with one S(6)U5 trigonal bipyramid. In the fifth S site, S(3) is bonded in a 5-coordinate geometry to one U(2), two equivalent U(1), and two equivalent U(3) atoms. In the sixth S site, S(4) is bonded to two equivalent U(2), two equivalent U(3), and one Sc(2) atom to form SScU4 square pyramids that share  a cornercorner with one S(4)ScU4 square pyramid, corners with two equivalent S(1)Sc2U3 trigonal bipyramids, corners with four equivalent S(6)U5 trigonal bipyramids, corners with two equivalent S(2)ScU3 trigonal pyramids, edges with two equivalent S(4)ScU4 square pyramids,  an edgeedge with one S(1)Sc2U3 trigonal bipyramid,  an edgeedge with one S(6)U5 trigonal bipyramid, and edges with four equivalent S(5)Sc2U3 trigonal bipyramids.
U3ScS6 crystallizes in the orthorhombic Pnnm space group. There are three inequivalent U sites. In the first U site, U(1) is bonded in a 8-coordinate geometry to one S(1), one S(5), two equivalent S(2), two equivalent S(3), and two equivalent S(6) atoms. The U(1)-S(1) bond length is 2.96 Å. The U(1)-S(5) bond length is 2.92 Å. Both U(1)-S(2) bond lengths are 2.77 Å. Both U(1)-S(3) bond lengths are 2.79 Å. Both U(1)-S(6) bond lengths are 2.86 Å. In the second U site, U(2) is bonded in a 8-coordinate geometry to one S(3), one S(5), two equivalent S(1), two equivalent S(4), and two equivalent S(6) atoms. The U(2)-S(3) bond length is 3.14 Å. The U(2)-S(5) bond length is 3.00 Å. Both U(2)-S(1) bond lengths are 2.85 Å. Both U(2)-S(4) bond lengths are 2.87 Å. Both U(2)-S(6) bond lengths are 2.77 Å. In the third U site, U(3) is bonded to one S(2), one S(5), one S(6), two equivalent S(3), and two equivalent S(4) atoms to form distorted US7 pentagonal bipyramids that share  a cornercorner with one Sc(1)S6 octahedra, edges with two equivalent Sc(2)S6 octahedra, and edges with two equivalent U(3)S7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 32°. The U(3)-S(2) bond length is 2.69 Å. The U(3)-S(5) bond length is 2.81 Å. The U(3)-S(6) bond length is 2.89 Å. Both U(3)-S(3) bond lengths are 2.74 Å. Both U(3)-S(4) bond lengths are 2.81 Å. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form ScS6 octahedra that share corners with two equivalent U(3)S7 pentagonal bipyramids and edges with two equivalent Sc(1)S6 octahedra. Both Sc(1)-S(2) bond lengths are 2.46 Å. All Sc(1)-S(1) bond lengths are 2.60 Å. In the second Sc site, Sc(2) is bonded to two equivalent S(4) and four equivalent S(5) atoms to form ScS6 octahedra that share edges with two equivalent Sc(2)S6 octahedra and edges with four equivalent U(3)S7 pentagonal bipyramids. Both Sc(2)-S(4) bond lengths are 2.56 Å. All Sc(2)-S(5) bond lengths are 2.59 Å. There are six inequivalent S sites. In the first S site, S(5) is bonded to one U(1), one U(2), one U(3), and two equivalent Sc(2) atoms to form distorted SSc2U3 trigonal bipyramids that share  a cornercorner with one S(6)U5 trigonal bipyramid, corners with three equivalent S(1)Sc2U3 trigonal bipyramids, corners with four equivalent S(5)Sc2U3 trigonal bipyramids, corners with three equivalent S(2)ScU3 trigonal pyramids, edges with four equivalent S(4)ScU4 square pyramids,  an edgeedge with one S(5)Sc2U3 trigonal bipyramid, and edges with two equivalent S(6)U5 trigonal bipyramids. In the second S site, S(6) is bonded to one U(3), two equivalent U(1), and two equivalent U(2) atoms to form distorted SU5 trigonal bipyramids that share corners with four equivalent S(4)ScU4 square pyramids,  a cornercorner with one S(5)Sc2U3 trigonal bipyramid, corners with four equivalent S(1)Sc2U3 trigonal bipyramids, corners with two equivalent S(2)ScU3 trigonal pyramids,  an edgeedge with one S(4)ScU4 square pyramid,  an edgeedge with one S(1)Sc2U3 trigonal bipyramid, edges with two equivalent S(5)Sc2U3 trigonal bipyramids, edges with two equivalent S(6)U5 trigonal bipyramids, and  a faceface with one S(2)ScU3 trigonal pyramid. In the third S site, S(1) is bonded to one U(1), two equivalent U(2), and two equivalent Sc(1) atoms to form distorted SSc2U3 trigonal bipyramids that share corners with two equivalent S(4)ScU4 square pyramids, corners with two equivalent S(1)Sc2U3 trigonal bipyramids, corners with three equivalent S(5)Sc2U3 trigonal bipyramids, corners with four equivalent S(6)U5 trigonal bipyramids, corners with two equivalent S(2)ScU3 trigonal pyramids,  an edgeedge with one S(4)ScU4 square pyramid,  an edgeedge with one S(6)U5 trigonal bipyramid, edges with three equivalent S(1)Sc2U3 trigonal bipyramids, and edges with two equivalent S(2)ScU3 trigonal pyramids. In the fourth S site, S(2) is bonded to one U(3), two equivalent U(1), and one Sc(1) atom to form distorted SScU3 trigonal pyramids that share corners with two equivalent S(4)ScU4 square pyramids, corners with two equivalent S(1)Sc2U3 trigonal bipyramids, corners with two equivalent S(6)U5 trigonal bipyramids, corners with three equivalent S(5)Sc2U3 trigonal bipyramids, corners with three equivalent S(2)ScU3 trigonal pyramids, edges with two equivalent S(1)Sc2U3 trigonal bipyramids, and  a faceface with one S(6)U5 trigonal bipyramid. In the fifth S site, S(3) is bonded in a 5-coordinate geometry to one U(2), two equivalent U(1), and two equivalent U(3) atoms. In the sixth S site, S(4) is bonded to two equivalent U(2), two equivalent U(3), and one Sc(2) atom to form SScU4 square pyramids that share  a cornercorner with one S(4)ScU4 square pyramid, corners with two equivalent S(1)Sc2U3 trigonal bipyramids, corners with four equivalent S(6)U5 trigonal bipyramids, corners with two equivalent S(2)ScU3 trigonal pyramids, edges with two equivalent S(4)ScU4 square pyramids,  an edgeedge with one S(1)Sc2U3 trigonal bipyramid,  an edgeedge with one S(6)U5 trigonal bipyramid, and edges with four equivalent S(5)Sc2U3 trigonal bipyramids.