Fe2CoSe4 crystallizes in the triclinic P1 space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one Se(1), one Se(2), two equivalent Se(3), and two equivalent Se(4) atoms. In the second Fe site, Fe(2) is bonded in a 6-coordinate geometry to one Se(3), one Se(4), two equivalent Se(1), and two equivalent Se(2) atoms. Co(1) is bonded in a 6-coordinate geometry to one Se(3), one Se(4), two equivalent Se(1), and two equivalent Se(2) atoms. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted pentagonal planar geometry to one Fe(1), two equivalent Fe(2), and two equivalent Co(1) atoms. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Fe(1), two equivalent Fe(2), and two equivalent Co(1) atoms. In the third Se site, Se(3) is bonded in a distorted rectangular see-saw-like geometry to one Fe(2), two equivalent Fe(1), and one Co(1) atom. In the fourth Se site, Se(4) is bonded in a distorted rectangular see-saw-like geometry to one Fe(2), two equivalent Fe(1), and one Co(1) atom.
Fe2CoSe4 crystallizes in the triclinic P1 space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one Se(1), one Se(2), two equivalent Se(3), and two equivalent Se(4) atoms. The Fe(1)-Se(1) bond length is 2.37 Å. The Fe(1)-Se(2) bond length is 2.51 Å. There is one shorter (2.43 Å) and one longer (2.46 Å) Fe(1)-Se(3) bond length. There is one shorter (2.32 Å) and one longer (2.79 Å) Fe(1)-Se(4) bond length. In the second Fe site, Fe(2) is bonded in a 6-coordinate geometry to one Se(3), one Se(4), two equivalent Se(1), and two equivalent Se(2) atoms. The Fe(2)-Se(3) bond length is 2.32 Å. The Fe(2)-Se(4) bond length is 2.67 Å. There is one shorter (2.37 Å) and one longer (2.52 Å) Fe(2)-Se(1) bond length. There is one shorter (2.35 Å) and one longer (2.81 Å) Fe(2)-Se(2) bond length. Co(1) is bonded in a 6-coordinate geometry to one Se(3), one Se(4), two equivalent Se(1), and two equivalent Se(2) atoms. The Co(1)-Se(3) bond length is 2.52 Å. The Co(1)-Se(4) bond length is 2.41 Å. There is one shorter (2.37 Å) and one longer (2.72 Å) Co(1)-Se(1) bond length. There is one shorter (2.42 Å) and one longer (2.43 Å) Co(1)-Se(2) bond length. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted pentagonal planar geometry to one Fe(1), two equivalent Fe(2), and two equivalent Co(1) atoms. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to one Fe(1), two equivalent Fe(2), and two equivalent Co(1) atoms. In the third Se site, Se(3) is bonded in a distorted rectangular see-saw-like geometry to one Fe(2), two equivalent Fe(1), and one Co(1) atom. In the fourth Se site, Se(4) is bonded in a distorted rectangular see-saw-like geometry to one Fe(2), two equivalent Fe(1), and one Co(1) atom.