Lu5BSi3 crystallizes in the hexagonal P6_3/mcm space group. There are two inequivalent Lu sites. In the first Lu site, Lu(1) is bonded in a 7-coordinate geometry to two equivalent B(1) and five equivalent Si(1) atoms. In the second Lu site, Lu(2) is bonded in a 6-coordinate geometry to six equivalent Si(1) atoms. B(1) is bonded to six equivalent Lu(1) atoms to form face-sharing BLu6 octahedra. Si(1) is bonded in a 9-coordinate geometry to four equivalent Lu(2) and five equivalent Lu(1) atoms.
Lu5BSi3 crystallizes in the hexagonal P6_3/mcm space group. There are two inequivalent Lu sites. In the first Lu site, Lu(1) is bonded in a 7-coordinate geometry to two equivalent B(1) and five equivalent Si(1) atoms. Both Lu(1)-B(1) bond lengths are 2.52 Å. There are a spread of Lu(1)-Si(1) bond distances ranging from 2.91-3.36 Å. In the second Lu site, Lu(2) is bonded in a 6-coordinate geometry to six equivalent Si(1) atoms. All Lu(2)-Si(1) bond lengths are 2.97 Å. B(1) is bonded to six equivalent Lu(1) atoms to form face-sharing BLu6 octahedra. Si(1) is bonded in a 9-coordinate geometry to four equivalent Lu(2) and five equivalent Lu(1) atoms.