Fe16Nb6Si7 crystallizes in the cubic Fm-3m space group. Nb(1) is bonded in a 12-coordinate geometry to four equivalent Fe(1), four equivalent Fe(2), and four equivalent Si(1) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(2) is bonded in a 12-coordinate geometry to three equivalent Nb(1), three equivalent Fe(1), three equivalent Fe(2), and three equivalent Si(1) atoms. In the second Fe site, Fe(1) is bonded in a 13-coordinate geometry to three equivalent Nb(1), three equivalent Fe(1), three equivalent Fe(2), one Si(2), and three equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to four equivalent Nb(1), four equivalent Fe(1), and four equivalent Fe(2) atoms to form a mixture of corner and face-sharing SiNb4Fe8 cuboctahedra. In the second Si site, Si(2) is bonded in a body-centered cubic geometry to eight equivalent Fe(1) atoms.
Fe16Nb6Si7 crystallizes in the cubic Fm-3m space group. Nb(1) is bonded in a 12-coordinate geometry to four equivalent Fe(1), four equivalent Fe(2), and four equivalent Si(1) atoms. All Nb(1)-Fe(1) bond lengths are 2.70 Å. All Nb(1)-Fe(2) bond lengths are 2.77 Å. All Nb(1)-Si(1) bond lengths are 2.83 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(2) is bonded in a 12-coordinate geometry to three equivalent Nb(1), three equivalent Fe(1), three equivalent Fe(2), and three equivalent Si(1) atoms. All Fe(2)-Fe(1) bond lengths are 2.44 Å. All Fe(2)-Fe(2) bond lengths are 2.39 Å. All Fe(2)-Si(1) bond lengths are 2.28 Å. In the second Fe site, Fe(1) is bonded in a 13-coordinate geometry to three equivalent Nb(1), three equivalent Fe(1), three equivalent Fe(2), one Si(2), and three equivalent Si(1) atoms. All Fe(1)-Fe(1) bond lengths are 2.68 Å. The Fe(1)-Si(2) bond length is 2.32 Å. All Fe(1)-Si(1) bond lengths are 2.45 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to four equivalent Nb(1), four equivalent Fe(1), and four equivalent Fe(2) atoms to form a mixture of corner and face-sharing SiNb4Fe8 cuboctahedra. In the second Si site, Si(2) is bonded in a body-centered cubic geometry to eight equivalent Fe(1) atoms.