U3S5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent U sites. In the first U site, U(1) is bonded to one S(1), one S(2), one S(3), and four equivalent S(4) atoms to form distorted edge-sharing US7 pentagonal bipyramids. In the second U site, U(2) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(2), two equivalent S(3), and two equivalent S(4) atoms. There are four inequivalent S sites. In the first S site, S(1) is bonded to one U(1) and four equivalent U(2) atoms to form distorted SU5 trigonal bipyramids that share  a cornercorner with one S(3)U5 square pyramid, corners with five equivalent S(2)U5 square pyramids, corners with four equivalent S(1)U5 trigonal bipyramids, corners with four equivalent S(4)U4 trigonal pyramids, edges with two equivalent S(2)U5 square pyramids, edges with four equivalent S(3)U5 square pyramids, and edges with four equivalent S(4)U4 trigonal pyramids. In the second S site, S(2) is bonded to one U(1) and four equivalent U(2) atoms to form SU5 square pyramids that share corners with four equivalent S(3)U5 square pyramids, corners with five equivalent S(1)U5 trigonal bipyramids, corners with eight equivalent S(4)U4 trigonal pyramids,  an edgeedge with one S(3)U5 square pyramid, edges with two equivalent S(2)U5 square pyramids, edges with two equivalent S(1)U5 trigonal bipyramids, edges with two equivalent S(4)U4 trigonal pyramids, and  a faceface with one S(3)U5 square pyramid. In the third S site, S(3) is bonded to one U(1) and four equivalent U(2) atoms to form distorted SU5 square pyramids that share corners with four equivalent S(2)U5 square pyramids, corners with four equivalent S(3)U5 square pyramids,  a cornercorner with one S(1)U5 trigonal bipyramid, corners with four equivalent S(4)U4 trigonal pyramids,  an edgeedge with one S(2)U5 square pyramid, edges with four equivalent S(1)U5 trigonal bipyramids, edges with four equivalent S(4)U4 trigonal pyramids, and  a faceface with one S(2)U5 square pyramid. In the fourth S site, S(4) is bonded to two equivalent U(1) and two equivalent U(2) atoms to form distorted SU4 trigonal pyramids that share corners with two equivalent S(3)U5 square pyramids, corners with four equivalent S(2)U5 square pyramids, corners with two equivalent S(1)U5 trigonal bipyramids, corners with six equivalent S(4)U4 trigonal pyramids,  an edgeedge with one S(2)U5 square pyramid, edges with two equivalent S(3)U5 square pyramids, edges with two equivalent S(1)U5 trigonal bipyramids, and  an edgeedge with one S(4)U4 trigonal pyramid.
U3S5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent U sites. In the first U site, U(1) is bonded to one S(1), one S(2), one S(3), and four equivalent S(4) atoms to form distorted edge-sharing US7 pentagonal bipyramids. The U(1)-S(1) bond length is 2.80 Å. The U(1)-S(2) bond length is 2.88 Å. The U(1)-S(3) bond length is 2.84 Å. There are two shorter (2.67 Å) and two longer (2.75 Å) U(1)-S(4) bond lengths. In the second U site, U(2) is bonded in a 8-coordinate geometry to two equivalent S(1), two equivalent S(2), two equivalent S(3), and two equivalent S(4) atoms. There is one shorter (2.95 Å) and one longer (3.05 Å) U(2)-S(1) bond length. There is one shorter (2.92 Å) and one longer (2.96 Å) U(2)-S(2) bond length. There is one shorter (2.88 Å) and one longer (2.94 Å) U(2)-S(3) bond length. There is one shorter (2.85 Å) and one longer (2.88 Å) U(2)-S(4) bond length. There are four inequivalent S sites. In the first S site, S(1) is bonded to one U(1) and four equivalent U(2) atoms to form distorted SU5 trigonal bipyramids that share  a cornercorner with one S(3)U5 square pyramid, corners with five equivalent S(2)U5 square pyramids, corners with four equivalent S(1)U5 trigonal bipyramids, corners with four equivalent S(4)U4 trigonal pyramids, edges with two equivalent S(2)U5 square pyramids, edges with four equivalent S(3)U5 square pyramids, and edges with four equivalent S(4)U4 trigonal pyramids. In the second S site, S(2) is bonded to one U(1) and four equivalent U(2) atoms to form SU5 square pyramids that share corners with four equivalent S(3)U5 square pyramids, corners with five equivalent S(1)U5 trigonal bipyramids, corners with eight equivalent S(4)U4 trigonal pyramids,  an edgeedge with one S(3)U5 square pyramid, edges with two equivalent S(2)U5 square pyramids, edges with two equivalent S(1)U5 trigonal bipyramids, edges with two equivalent S(4)U4 trigonal pyramids, and  a faceface with one S(3)U5 square pyramid. In the third S site, S(3) is bonded to one U(1) and four equivalent U(2) atoms to form distorted SU5 square pyramids that share corners with four equivalent S(2)U5 square pyramids, corners with four equivalent S(3)U5 square pyramids,  a cornercorner with one S(1)U5 trigonal bipyramid, corners with four equivalent S(4)U4 trigonal pyramids,  an edgeedge with one S(2)U5 square pyramid, edges with four equivalent S(1)U5 trigonal bipyramids, edges with four equivalent S(4)U4 trigonal pyramids, and  a faceface with one S(2)U5 square pyramid. In the fourth S site, S(4) is bonded to two equivalent U(1) and two equivalent U(2) atoms to form distorted SU4 trigonal pyramids that share corners with two equivalent S(3)U5 square pyramids, corners with four equivalent S(2)U5 square pyramids, corners with two equivalent S(1)U5 trigonal bipyramids, corners with six equivalent S(4)U4 trigonal pyramids,  an edgeedge with one S(2)U5 square pyramid, edges with two equivalent S(3)U5 square pyramids, edges with two equivalent S(1)U5 trigonal bipyramids, and  an edgeedge with one S(4)U4 trigonal pyramid.