Ni9B2Si4 crystallizes in the tetragonal I-42m space group. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 2-coordinate geometry to two equivalent B(1) and four equivalent Si(1) atoms. In the second Ni site, Ni(2) is bonded in a distorted tetrahedral geometry to four equivalent Si(1) atoms. B(1) is bonded in a 10-coordinate geometry to eight equivalent Ni(1) and two equivalent B(1) atoms. Si(1) is bonded in a 9-coordinate geometry to one Ni(2) and eight equivalent Ni(1) atoms.
Ni9B2Si4 crystallizes in the tetragonal I-42m space group. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 2-coordinate geometry to two equivalent B(1) and four equivalent Si(1) atoms. Both Ni(1)-B(1) bond lengths are 2.17 Å. There are a spread of Ni(1)-Si(1) bond distances ranging from 2.32-2.59 Å. In the second Ni site, Ni(2) is bonded in a distorted tetrahedral geometry to four equivalent Si(1) atoms. All Ni(2)-Si(1) bond lengths are 2.25 Å. B(1) is bonded in a 10-coordinate geometry to eight equivalent Ni(1) and two equivalent B(1) atoms. Both B(1)-B(1) bond lengths are 2.08 Å. Si(1) is bonded in a 9-coordinate geometry to one Ni(2) and eight equivalent Ni(1) atoms.