Fe4NiSe10 is Marcasite-derived structured and crystallizes in the monoclinic P2/m space group. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one Se(1), one Se(2), two equivalent Se(6), and two equivalent Se(7) atoms to form a mixture of edge and corner-sharing FeSe6 octahedra. The corner-sharing octahedral tilt angles are 57°. In the second Fe site, Fe(2) is bonded to one Se(3), one Se(5), two equivalent Se(10), and two equivalent Se(8) atoms to form FeSe6 octahedra that share corners with four equivalent Fe(4)Se6 octahedra, corners with four equivalent Ni(1)Se6 octahedra, and edges with two equivalent Fe(2)Se6 octahedra. The corner-sharing octahedral tilt angles range from 57-58°. In the third Fe site, Fe(3) is bonded to two equivalent Se(4) and four equivalent Se(9) atoms to form FeSe6 octahedra that share corners with eight equivalent Ni(1)Se6 octahedra and edges with two equivalent Fe(3)Se6 octahedra. The corner-sharing octahedral tilt angles range from 57-58°. In the fourth Fe site, Fe(4) is bonded to one Se(6), one Se(8), two equivalent Se(1), and two equivalent Se(3) atoms to form a mixture of edge and corner-sharing FeSe6 octahedra. The corner-sharing octahedral tilt angles are 57°. In the fifth Fe site, Fe(5) is bonded to two equivalent Se(7) and four equivalent Se(2) atoms to form a mixture of edge and corner-sharing FeSe6 octahedra. The corner-sharing octahedral tilt angles are 57°. Ni(1) is bonded to one Se(10), one Se(9), two equivalent Se(4), and two equivalent Se(5) atoms to form NiSe6 octahedra that share corners with four equivalent Fe(2)Se6 octahedra, corners with four equivalent Fe(3)Se6 octahedra, and edges with two equivalent Ni(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 57-58°. There are ten inequivalent Se sites. In the first Se site, Se(1) is bonded in a 3-coordinate geometry to one Fe(1) and two equivalent Fe(4) atoms. In the second Se site, Se(2) is bonded in a 3-coordinate geometry to one Fe(1) and two equivalent Fe(5) atoms. In the third Se site, Se(3) is bonded in a 3-coordinate geometry to one Fe(2) and two equivalent Fe(4) atoms. In the fourth Se site, Se(4) is bonded in a 3-coordinate geometry to one Fe(3) and two equivalent Ni(1) atoms. In the fifth Se site, Se(5) is bonded in a 3-coordinate geometry to one Fe(2) and two equivalent Ni(1) atoms. In the sixth Se site, Se(6) is bonded in a 3-coordinate geometry to one Fe(4) and two equivalent Fe(1) atoms. In the seventh Se site, Se(7) is bonded in a 3-coordinate geometry to one Fe(5) and two equivalent Fe(1) atoms. In the eighth Se site, Se(8) is bonded in a 3-coordinate geometry to one Fe(4) and two equivalent Fe(2) atoms. In the ninth Se site, Se(9) is bonded in a 3-coordinate geometry to two equivalent Fe(3) and one Ni(1) atom. In the tenth Se site, Se(10) is bonded in a 3-coordinate geometry to two equivalent Fe(2) and one Ni(1) atom.
Fe4NiSe10 is Marcasite-derived structured and crystallizes in the monoclinic P2/m space group. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one Se(1), one Se(2), two equivalent Se(6), and two equivalent Se(7) atoms to form a mixture of edge and corner-sharing FeSe6 octahedra. The corner-sharing octahedral tilt angles are 57°. The Fe(1)-Se(1) bond length is 2.38 Å. The Fe(1)-Se(2) bond length is 2.39 Å. Both Fe(1)-Se(6) bond lengths are 2.39 Å. Both Fe(1)-Se(7) bond lengths are 2.39 Å. In the second Fe site, Fe(2) is bonded to one Se(3), one Se(5), two equivalent Se(10), and two equivalent Se(8) atoms to form FeSe6 octahedra that share corners with four equivalent Fe(4)Se6 octahedra, corners with four equivalent Ni(1)Se6 octahedra, and edges with two equivalent Fe(2)Se6 octahedra. The corner-sharing octahedral tilt angles range from 57-58°. The Fe(2)-Se(3) bond length is 2.39 Å. The Fe(2)-Se(5) bond length is 2.35 Å. Both Fe(2)-Se(10) bond lengths are 2.37 Å. Both Fe(2)-Se(8) bond lengths are 2.40 Å. In the third Fe site, Fe(3) is bonded to two equivalent Se(4) and four equivalent Se(9) atoms to form FeSe6 octahedra that share corners with eight equivalent Ni(1)Se6 octahedra and edges with two equivalent Fe(3)Se6 octahedra. The corner-sharing octahedral tilt angles range from 57-58°. Both Fe(3)-Se(4) bond lengths are 2.35 Å. All Fe(3)-Se(9) bond lengths are 2.38 Å. In the fourth Fe site, Fe(4) is bonded to one Se(6), one Se(8), two equivalent Se(1), and two equivalent Se(3) atoms to form a mixture of edge and corner-sharing FeSe6 octahedra. The corner-sharing octahedral tilt angles are 57°. The Fe(4)-Se(6) bond length is 2.38 Å. The Fe(4)-Se(8) bond length is 2.37 Å. Both Fe(4)-Se(1) bond lengths are 2.39 Å. Both Fe(4)-Se(3) bond lengths are 2.39 Å. In the fifth Fe site, Fe(5) is bonded to two equivalent Se(7) and four equivalent Se(2) atoms to form a mixture of edge and corner-sharing FeSe6 octahedra. The corner-sharing octahedral tilt angles are 57°. Both Fe(5)-Se(7) bond lengths are 2.38 Å. All Fe(5)-Se(2) bond lengths are 2.39 Å. Ni(1) is bonded to one Se(10), one Se(9), two equivalent Se(4), and two equivalent Se(5) atoms to form NiSe6 octahedra that share corners with four equivalent Fe(2)Se6 octahedra, corners with four equivalent Fe(3)Se6 octahedra, and edges with two equivalent Ni(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 57-58°. The Ni(1)-Se(10) bond length is 2.43 Å. The Ni(1)-Se(9) bond length is 2.42 Å. Both Ni(1)-Se(4) bond lengths are 2.43 Å. Both Ni(1)-Se(5) bond lengths are 2.43 Å. There are ten inequivalent Se sites. In the first Se site, Se(1) is bonded in a 3-coordinate geometry to one Fe(1) and two equivalent Fe(4) atoms. In the second Se site, Se(2) is bonded in a 3-coordinate geometry to one Fe(1) and two equivalent Fe(5) atoms. In the third Se site, Se(3) is bonded in a 3-coordinate geometry to one Fe(2) and two equivalent Fe(4) atoms. In the fourth Se site, Se(4) is bonded in a 3-coordinate geometry to one Fe(3) and two equivalent Ni(1) atoms. In the fifth Se site, Se(5) is bonded in a 3-coordinate geometry to one Fe(2) and two equivalent Ni(1) atoms. In the sixth Se site, Se(6) is bonded in a 3-coordinate geometry to one Fe(4) and two equivalent Fe(1) atoms. In the seventh Se site, Se(7) is bonded in a 3-coordinate geometry to one Fe(5) and two equivalent Fe(1) atoms. In the eighth Se site, Se(8) is bonded in a 3-coordinate geometry to one Fe(4) and two equivalent Fe(2) atoms. In the ninth Se site, Se(9) is bonded in a 3-coordinate geometry to two equivalent Fe(3) and one Ni(1) atom. In the tenth Se site, Se(10) is bonded in a 3-coordinate geometry to two equivalent Fe(2) and one Ni(1) atom.