Fe5BSi2 crystallizes in the tetragonal I4/mcm space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 4-coordinate geometry to two equivalent B(1) and four equivalent Si(1) atoms. In the second Fe site, Fe(2) is bonded in a 6-coordinate geometry to two equivalent Fe(2) and four equivalent Si(1) atoms. B(1) is bonded in a 10-coordinate geometry to eight equivalent Fe(1) and two equivalent B(1) atoms. Si(1) is bonded in a 10-coordinate geometry to two equivalent Fe(2) and eight equivalent Fe(1) atoms.
Fe5BSi2 crystallizes in the tetragonal I4/mcm space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 4-coordinate geometry to two equivalent B(1) and four equivalent Si(1) atoms. Both Fe(1)-B(1) bond lengths are 2.21 Å. There are a spread of Fe(1)-Si(1) bond distances ranging from 2.30-2.60 Å. In the second Fe site, Fe(2) is bonded in a 6-coordinate geometry to two equivalent Fe(2) and four equivalent Si(1) atoms. Both Fe(2)-Fe(2) bond lengths are 2.21 Å. All Fe(2)-Si(1) bond lengths are 2.33 Å. B(1) is bonded in a 10-coordinate geometry to eight equivalent Fe(1) and two equivalent B(1) atoms. Both B(1)-B(1) bond lengths are 2.21 Å. Si(1) is bonded in a 10-coordinate geometry to two equivalent Fe(2) and eight equivalent Fe(1) atoms.