Fe4N2Se3 crystallizes in the monoclinic C2/m space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 4-coordinate geometry to three equivalent N(1) and one Se(1) atom. In the second Fe site, Fe(2) is bonded in a 1-coordinate geometry to one N(1), two equivalent Se(1), and three equivalent Se(2) atoms. N(1) is bonded in a see-saw-like geometry to one Fe(2) and three equivalent Fe(1) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted hexagonal planar geometry to two equivalent Fe(1) and four equivalent Fe(2) atoms. In the second Se site, Se(2) is bonded in a distorted T-shaped geometry to three equivalent Fe(2) atoms.
Fe4N2Se3 crystallizes in the monoclinic C2/m space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 4-coordinate geometry to three equivalent N(1) and one Se(1) atom. There is one shorter (1.81 Å) and two longer (1.87 Å) Fe(1)-N(1) bond lengths. The Fe(1)-Se(1) bond length is 2.34 Å. In the second Fe site, Fe(2) is bonded in a 1-coordinate geometry to one N(1), two equivalent Se(1), and three equivalent Se(2) atoms. The Fe(2)-N(1) bond length is 1.80 Å. Both Fe(2)-Se(1) bond lengths are 2.64 Å. There are two shorter (2.36 Å) and one longer (2.44 Å) Fe(2)-Se(2) bond length. N(1) is bonded in a see-saw-like geometry to one Fe(2) and three equivalent Fe(1) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted hexagonal planar geometry to two equivalent Fe(1) and four equivalent Fe(2) atoms. In the second Se site, Se(2) is bonded in a distorted T-shaped geometry to three equivalent Fe(2) atoms.