Bi3Lu5 crystallizes in the orthorhombic Pnma space group. There are four inequivalent Lu sites. In the first Lu site, Lu(1) is bonded to one Bi(1) and four equivalent Bi(2) atoms to form distorted LuBi5 square pyramids that share corners with five equivalent Lu(3)Bi6 octahedra,  an edgeedge with one Lu(3)Bi6 octahedra, edges with two equivalent Lu(1)Bi5 square pyramids, and  a faceface with one Lu(3)Bi6 octahedra. The corner-sharing octahedral tilt angles range from 35-45°. In the second Lu site, Lu(2) is bonded in a 5-coordinate geometry to one Bi(1) and four equivalent Bi(2) atoms. In the third Lu site, Lu(3) is bonded to two equivalent Bi(1) and four equivalent Bi(2) atoms to form distorted LuBi6 octahedra that share corners with five equivalent Lu(1)Bi5 square pyramids,  an edgeedge with one Lu(1)Bi5 square pyramid, faces with two equivalent Lu(3)Bi6 octahedra, and  a faceface with one Lu(1)Bi5 square pyramid. In the fourth Lu site, Lu(4) is bonded in a 5-coordinate geometry to two equivalent Bi(1) and three equivalent Bi(2) atoms. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 8-coordinate geometry to one Lu(1), one Lu(2), two equivalent Lu(3), and four equivalent Lu(4) atoms. In the second Bi site, Bi(2) is bonded in a 9-coordinate geometry to two equivalent Lu(1), two equivalent Lu(2), two equivalent Lu(3), and three equivalent Lu(4) atoms.
Bi3Lu5 crystallizes in the orthorhombic Pnma space group. There are four inequivalent Lu sites. In the first Lu site, Lu(1) is bonded to one Bi(1) and four equivalent Bi(2) atoms to form distorted LuBi5 square pyramids that share corners with five equivalent Lu(3)Bi6 octahedra,  an edgeedge with one Lu(3)Bi6 octahedra, edges with two equivalent Lu(1)Bi5 square pyramids, and  a faceface with one Lu(3)Bi6 octahedra. The corner-sharing octahedral tilt angles range from 35-45°. The Lu(1)-Bi(1) bond length is 3.08 Å. There are two shorter (3.12 Å) and two longer (3.17 Å) Lu(1)-Bi(2) bond lengths. In the second Lu site, Lu(2) is bonded in a 5-coordinate geometry to one Bi(1) and four equivalent Bi(2) atoms. The Lu(2)-Bi(1) bond length is 3.06 Å. There are two shorter (3.12 Å) and two longer (3.31 Å) Lu(2)-Bi(2) bond lengths. In the third Lu site, Lu(3) is bonded to two equivalent Bi(1) and four equivalent Bi(2) atoms to form distorted LuBi6 octahedra that share corners with five equivalent Lu(1)Bi5 square pyramids,  an edgeedge with one Lu(1)Bi5 square pyramid, faces with two equivalent Lu(3)Bi6 octahedra, and  a faceface with one Lu(1)Bi5 square pyramid. There is one shorter (3.06 Å) and one longer (3.33 Å) Lu(3)-Bi(1) bond length. There are two shorter (3.13 Å) and two longer (3.37 Å) Lu(3)-Bi(2) bond lengths. In the fourth Lu site, Lu(4) is bonded in a 5-coordinate geometry to two equivalent Bi(1) and three equivalent Bi(2) atoms. There is one shorter (3.05 Å) and one longer (3.13 Å) Lu(4)-Bi(1) bond length. There are a spread of Lu(4)-Bi(2) bond distances ranging from 3.33-3.44 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 8-coordinate geometry to one Lu(1), one Lu(2), two equivalent Lu(3), and four equivalent Lu(4) atoms. In the second Bi site, Bi(2) is bonded in a 9-coordinate geometry to two equivalent Lu(1), two equivalent Lu(2), two equivalent Lu(3), and three equivalent Lu(4) atoms.