PbU2Se5 crystallizes in the orthorhombic Pnma space group. U(1) is bonded in a 8-coordinate geometry to two equivalent Se(1), two equivalent Se(2), two equivalent Se(3), and two equivalent Se(4) atoms. Pb(1) is bonded in a 7-coordinate geometry to one Se(2), one Se(3), one Se(4), and four equivalent Se(1) atoms. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent U(1) and two equivalent Pb(1) atoms to form distorted SeU2Pb2 tetrahedra that share corners with two equivalent Se(4)U4Pb square pyramids, corners with four equivalent Se(3)U4Pb square pyramids, corners with six equivalent Se(1)U2Pb2 tetrahedra, corners with two equivalent Se(2)U4Pb trigonal bipyramids,  an edgeedge with one Se(3)U4Pb square pyramid, edges with two equivalent Se(4)U4Pb square pyramids,  an edgeedge with one Se(1)U2Pb2 tetrahedra, and edges with two equivalent Se(2)U4Pb trigonal bipyramids. In the second Se site, Se(2) is bonded to four equivalent U(1) and one Pb(1) atom to form distorted SeU4Pb trigonal bipyramids that share  a cornercorner with one Se(4)U4Pb square pyramid, corners with five equivalent Se(3)U4Pb square pyramids, corners with four equivalent Se(1)U2Pb2 tetrahedra, corners with four equivalent Se(2)U4Pb trigonal bipyramids, edges with two equivalent Se(3)U4Pb square pyramids, edges with four equivalent Se(4)U4Pb square pyramids, and edges with four equivalent Se(1)U2Pb2 tetrahedra. In the third Se site, Se(3) is bonded to four equivalent U(1) and one Pb(1) atom to form distorted SeU4Pb square pyramids that share corners with four equivalent Se(4)U4Pb square pyramids, corners with eight equivalent Se(1)U2Pb2 tetrahedra, corners with five equivalent Se(2)U4Pb trigonal bipyramids,  an edgeedge with one Se(4)U4Pb square pyramid, edges with two equivalent Se(3)U4Pb square pyramids, edges with two equivalent Se(1)U2Pb2 tetrahedra, edges with two equivalent Se(2)U4Pb trigonal bipyramids, and  a faceface with one Se(4)U4Pb square pyramid. In the fourth Se site, Se(4) is bonded to four equivalent U(1) and one Pb(1) atom to form distorted SeU4Pb square pyramids that share corners with four equivalent Se(3)U4Pb square pyramids, corners with four equivalent Se(4)U4Pb square pyramids, corners with four equivalent Se(1)U2Pb2 tetrahedra,  a cornercorner with one Se(2)U4Pb trigonal bipyramid,  an edgeedge with one Se(3)U4Pb square pyramid, edges with four equivalent Se(1)U2Pb2 tetrahedra, edges with four equivalent Se(2)U4Pb trigonal bipyramids, and  a faceface with one Se(3)U4Pb square pyramid.
PbU2Se5 crystallizes in the orthorhombic Pnma space group. U(1) is bonded in a 8-coordinate geometry to two equivalent Se(1), two equivalent Se(2), two equivalent Se(3), and two equivalent Se(4) atoms. There is one shorter (2.85 Å) and one longer (2.86 Å) U(1)-Se(1) bond length. There is one shorter (3.06 Å) and one longer (3.13 Å) U(1)-Se(2) bond length. There is one shorter (3.07 Å) and one longer (3.09 Å) U(1)-Se(3) bond length. There is one shorter (2.98 Å) and one longer (3.04 Å) U(1)-Se(4) bond length. Pb(1) is bonded in a 7-coordinate geometry to one Se(2), one Se(3), one Se(4), and four equivalent Se(1) atoms. The Pb(1)-Se(2) bond length is 2.98 Å. The Pb(1)-Se(3) bond length is 3.25 Å. The Pb(1)-Se(4) bond length is 3.04 Å. There are two shorter (2.87 Å) and two longer (3.03 Å) Pb(1)-Se(1) bond lengths. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent U(1) and two equivalent Pb(1) atoms to form distorted SeU2Pb2 tetrahedra that share corners with two equivalent Se(4)U4Pb square pyramids, corners with four equivalent Se(3)U4Pb square pyramids, corners with six equivalent Se(1)U2Pb2 tetrahedra, corners with two equivalent Se(2)U4Pb trigonal bipyramids,  an edgeedge with one Se(3)U4Pb square pyramid, edges with two equivalent Se(4)U4Pb square pyramids,  an edgeedge with one Se(1)U2Pb2 tetrahedra, and edges with two equivalent Se(2)U4Pb trigonal bipyramids. In the second Se site, Se(2) is bonded to four equivalent U(1) and one Pb(1) atom to form distorted SeU4Pb trigonal bipyramids that share  a cornercorner with one Se(4)U4Pb square pyramid, corners with five equivalent Se(3)U4Pb square pyramids, corners with four equivalent Se(1)U2Pb2 tetrahedra, corners with four equivalent Se(2)U4Pb trigonal bipyramids, edges with two equivalent Se(3)U4Pb square pyramids, edges with four equivalent Se(4)U4Pb square pyramids, and edges with four equivalent Se(1)U2Pb2 tetrahedra. In the third Se site, Se(3) is bonded to four equivalent U(1) and one Pb(1) atom to form distorted SeU4Pb square pyramids that share corners with four equivalent Se(4)U4Pb square pyramids, corners with eight equivalent Se(1)U2Pb2 tetrahedra, corners with five equivalent Se(2)U4Pb trigonal bipyramids,  an edgeedge with one Se(4)U4Pb square pyramid, edges with two equivalent Se(3)U4Pb square pyramids, edges with two equivalent Se(1)U2Pb2 tetrahedra, edges with two equivalent Se(2)U4Pb trigonal bipyramids, and  a faceface with one Se(4)U4Pb square pyramid. In the fourth Se site, Se(4) is bonded to four equivalent U(1) and one Pb(1) atom to form distorted SeU4Pb square pyramids that share corners with four equivalent Se(3)U4Pb square pyramids, corners with four equivalent Se(4)U4Pb square pyramids, corners with four equivalent Se(1)U2Pb2 tetrahedra,  a cornercorner with one Se(2)U4Pb trigonal bipyramid,  an edgeedge with one Se(3)U4Pb square pyramid, edges with four equivalent Se(1)U2Pb2 tetrahedra, edges with four equivalent Se(2)U4Pb trigonal bipyramids, and  a faceface with one Se(3)U4Pb square pyramid.