CaU2S5 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded to one S(1), one S(2), one S(3), and four equivalent S(4) atoms to form distorted edge-sharing CaS7 pentagonal bipyramids. U(1) 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 Ca(1) and four equivalent U(1) atoms to form SCaU4 square pyramids that share corners with four equivalent S(1)CaU4 square pyramids, corners with four equivalent S(3)CaU4 square pyramids, corners with four equivalent S(4)Ca2U2 tetrahedra,  a cornercorner with one S(2)CaU4 trigonal bipyramid,  an edgeedge with one S(3)CaU4 square pyramid, edges with four equivalent S(4)Ca2U2 tetrahedra, edges with four equivalent S(2)CaU4 trigonal bipyramids, and  a faceface with one S(3)CaU4 square pyramid. In the second S site, S(2) is bonded to one Ca(1) and four equivalent U(1) atoms to form distorted SCaU4 trigonal bipyramids that share  a cornercorner with one S(1)CaU4 square pyramid, corners with five equivalent S(3)CaU4 square pyramids, corners with four equivalent S(4)Ca2U2 tetrahedra, corners with four equivalent S(2)CaU4 trigonal bipyramids, edges with two equivalent S(3)CaU4 square pyramids, edges with four equivalent S(1)CaU4 square pyramids, and edges with four equivalent S(4)Ca2U2 tetrahedra. In the third S site, S(3) is bonded to one Ca(1) and four equivalent U(1) atoms to form SCaU4 square pyramids that share corners with four equivalent S(1)CaU4 square pyramids, corners with eight equivalent S(4)Ca2U2 tetrahedra, corners with five equivalent S(2)CaU4 trigonal bipyramids,  an edgeedge with one S(1)CaU4 square pyramid, edges with two equivalent S(3)CaU4 square pyramids, edges with two equivalent S(4)Ca2U2 tetrahedra, edges with two equivalent S(2)CaU4 trigonal bipyramids, and  a faceface with one S(1)CaU4 square pyramid. In the fourth S site, S(4) is bonded to two equivalent Ca(1) and two equivalent U(1) atoms to form distorted SCa2U2 tetrahedra that share corners with two equivalent S(1)CaU4 square pyramids, corners with four equivalent S(3)CaU4 square pyramids, corners with six equivalent S(4)Ca2U2 tetrahedra, corners with two equivalent S(2)CaU4 trigonal bipyramids,  an edgeedge with one S(3)CaU4 square pyramid, edges with two equivalent S(1)CaU4 square pyramids,  an edgeedge with one S(4)Ca2U2 tetrahedra, and edges with two equivalent S(2)CaU4 trigonal bipyramids.
CaU2S5 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded to one S(1), one S(2), one S(3), and four equivalent S(4) atoms to form distorted edge-sharing CaS7 pentagonal bipyramids. The Ca(1)-S(1) bond length is 2.78 Å. The Ca(1)-S(2) bond length is 2.81 Å. The Ca(1)-S(3) bond length is 2.94 Å. There are two shorter (2.69 Å) and two longer (2.77 Å) Ca(1)-S(4) bond lengths. U(1) 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 (2.80 Å) and one longer (2.87 Å) U(1)-S(1) bond length. There is one shorter (2.86 Å) and one longer (2.98 Å) U(1)-S(2) bond length. There is one shorter (2.88 Å) and one longer (2.94 Å) U(1)-S(3) bond length. There is one shorter (2.66 Å) and one longer (2.70 Å) U(1)-S(4) bond length. There are four inequivalent S sites. In the first S site, S(1) is bonded to one Ca(1) and four equivalent U(1) atoms to form SCaU4 square pyramids that share corners with four equivalent S(1)CaU4 square pyramids, corners with four equivalent S(3)CaU4 square pyramids, corners with four equivalent S(4)Ca2U2 tetrahedra,  a cornercorner with one S(2)CaU4 trigonal bipyramid,  an edgeedge with one S(3)CaU4 square pyramid, edges with four equivalent S(4)Ca2U2 tetrahedra, edges with four equivalent S(2)CaU4 trigonal bipyramids, and  a faceface with one S(3)CaU4 square pyramid. In the second S site, S(2) is bonded to one Ca(1) and four equivalent U(1) atoms to form distorted SCaU4 trigonal bipyramids that share  a cornercorner with one S(1)CaU4 square pyramid, corners with five equivalent S(3)CaU4 square pyramids, corners with four equivalent S(4)Ca2U2 tetrahedra, corners with four equivalent S(2)CaU4 trigonal bipyramids, edges with two equivalent S(3)CaU4 square pyramids, edges with four equivalent S(1)CaU4 square pyramids, and edges with four equivalent S(4)Ca2U2 tetrahedra. In the third S site, S(3) is bonded to one Ca(1) and four equivalent U(1) atoms to form SCaU4 square pyramids that share corners with four equivalent S(1)CaU4 square pyramids, corners with eight equivalent S(4)Ca2U2 tetrahedra, corners with five equivalent S(2)CaU4 trigonal bipyramids,  an edgeedge with one S(1)CaU4 square pyramid, edges with two equivalent S(3)CaU4 square pyramids, edges with two equivalent S(4)Ca2U2 tetrahedra, edges with two equivalent S(2)CaU4 trigonal bipyramids, and  a faceface with one S(1)CaU4 square pyramid. In the fourth S site, S(4) is bonded to two equivalent Ca(1) and two equivalent U(1) atoms to form distorted SCa2U2 tetrahedra that share corners with two equivalent S(1)CaU4 square pyramids, corners with four equivalent S(3)CaU4 square pyramids, corners with six equivalent S(4)Ca2U2 tetrahedra, corners with two equivalent S(2)CaU4 trigonal bipyramids,  an edgeedge with one S(3)CaU4 square pyramid, edges with two equivalent S(1)CaU4 square pyramids,  an edgeedge with one S(4)Ca2U2 tetrahedra, and edges with two equivalent S(2)CaU4 trigonal bipyramids.