Fe4N2Se3 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a distorted L-shaped geometry to two equivalent N(1) and two equivalent Se(2) atoms. In the second Fe site, Fe(2) is bonded to two equivalent N(1) and two equivalent Se(1) atoms to form distorted corner-sharing FeSe2N2 trigonal pyramids. In the third Fe site, Fe(3) is bonded in a 6-coordinate geometry to two equivalent N(1), one Se(1), and three equivalent Se(2) atoms. N(1) is bonded in a distorted see-saw-like geometry to one Fe(1), one Fe(2), and two equivalent Fe(3) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Fe(2) and two equivalent Fe(3) atoms to form distorted corner-sharing SeFe4 tetrahedra. In the second Se site, Se(2) is bonded in a 4-coordinate geometry to one Fe(1) and three equivalent Fe(3) atoms.
Fe4N2Se3 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a distorted L-shaped geometry to two equivalent N(1) and two equivalent Se(2) atoms. Both Fe(1)-N(1) bond lengths are 1.92 Å. Both Fe(1)-Se(2) bond lengths are 2.57 Å. In the second Fe site, Fe(2) is bonded to two equivalent N(1) and two equivalent Se(1) atoms to form distorted corner-sharing FeSe2N2 trigonal pyramids. Both Fe(2)-N(1) bond lengths are 1.75 Å. There is one shorter (2.31 Å) and one longer (2.40 Å) Fe(2)-Se(1) bond length. In the third Fe site, Fe(3) is bonded in a 6-coordinate geometry to two equivalent N(1), one Se(1), and three equivalent Se(2) atoms. There is one shorter (1.84 Å) and one longer (1.85 Å) Fe(3)-N(1) bond length. The Fe(3)-Se(1) bond length is 2.49 Å. There are a spread of Fe(3)-Se(2) bond distances ranging from 2.46-2.54 Å. N(1) is bonded in a distorted see-saw-like geometry to one Fe(1), one Fe(2), and two equivalent Fe(3) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Fe(2) and two equivalent Fe(3) atoms to form distorted corner-sharing SeFe4 tetrahedra. In the second Se site, Se(2) is bonded in a 4-coordinate geometry to one Fe(1) and three equivalent Fe(3) atoms.