Na2Fe3S4 crystallizes in the monoclinic Cm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one S(2), one S(4), two equivalent S(1), and two equivalent S(3) atoms to form distorted NaS6 octahedra that share  a cornercorner with one Fe(2)S4 tetrahedra, corners with five equivalent Fe(1)S4 tetrahedra, corners with five equivalent Fe(3)S4 tetrahedra, edges with two equivalent Na(1)S6 octahedra, edges with four equivalent Na(2)S6 octahedra,  an edgeedge with one Fe(1)S4 tetrahedra,  an edgeedge with one Fe(3)S4 tetrahedra, and edges with two equivalent Fe(2)S4 tetrahedra. In the second Na site, Na(2) is bonded to one S(1), one S(3), two equivalent S(2), and two equivalent S(4) atoms to form distorted NaS6 octahedra that share  a cornercorner with one Fe(1)S4 tetrahedra,  a cornercorner with one Fe(3)S4 tetrahedra, corners with five equivalent Fe(2)S4 tetrahedra, edges with two equivalent Na(2)S6 octahedra, edges with four equivalent Na(1)S6 octahedra,  an edgeedge with one Fe(2)S4 tetrahedra, edges with two equivalent Fe(1)S4 tetrahedra, and edges with two equivalent Fe(3)S4 tetrahedra. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form FeS4 tetrahedra that share  a cornercorner with one Na(2)S6 octahedra, corners with five equivalent Na(1)S6 octahedra, corners with two equivalent Fe(1)S4 tetrahedra,  an edgeedge with one Na(1)S6 octahedra, edges with two equivalent Na(2)S6 octahedra,  an edgeedge with one Fe(2)S4 tetrahedra, and edges with two equivalent Fe(3)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-51°. In the second Fe site, Fe(2) is bonded to one S(2), one S(3), and two equivalent S(4) atoms to form FeS4 tetrahedra that share  a cornercorner with one Na(1)S6 octahedra, corners with five equivalent Na(2)S6 octahedra, corners with two equivalent Fe(2)S4 tetrahedra, corners with four equivalent Fe(3)S4 tetrahedra,  an edgeedge with one Na(2)S6 octahedra, edges with two equivalent Na(1)S6 octahedra, and  an edgeedge with one Fe(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-54°. In the third Fe site, Fe(3) is bonded to one S(1), one S(4), and two equivalent S(3) atoms to form FeS4 tetrahedra that share  a cornercorner with one Na(2)S6 octahedra, corners with five equivalent Na(1)S6 octahedra, corners with two equivalent Fe(3)S4 tetrahedra, corners with four equivalent Fe(2)S4 tetrahedra,  an edgeedge with one Na(1)S6 octahedra, edges with two equivalent Na(2)S6 octahedra, and edges with two equivalent Fe(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 27-52°. There are four inequivalent S sites. In the first S site, S(1) is bonded to one Na(2), two equivalent Na(1), one Fe(3), and two equivalent Fe(1) atoms to form distorted SNa3Fe3 octahedra that share corners with two equivalent S(2)Na3Fe2 square pyramids, edges with two equivalent S(1)Na3Fe3 octahedra, and edges with two equivalent S(2)Na3Fe2 square pyramids. In the second S site, S(2) is bonded to one Na(1), two equivalent Na(2), one Fe(1), and one Fe(2) atom to form distorted SNa3Fe2 square pyramids that share corners with two equivalent S(1)Na3Fe3 octahedra, corners with two equivalent S(2)Na3Fe2 square pyramids, and edges with two equivalent S(1)Na3Fe3 octahedra. The corner-sharing octahedral tilt angles are 94°. In the third S site, S(3) is bonded in a 7-coordinate geometry to one Na(2), two equivalent Na(1), one Fe(1), one Fe(2), and two equivalent Fe(3) atoms. In the fourth S site, S(4) is bonded in a 6-coordinate geometry to one Na(1), two equivalent Na(2), one Fe(3), and two equivalent Fe(2) atoms.
Na2Fe3S4 crystallizes in the monoclinic Cm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one S(2), one S(4), two equivalent S(1), and two equivalent S(3) atoms to form distorted NaS6 octahedra that share  a cornercorner with one Fe(2)S4 tetrahedra, corners with five equivalent Fe(1)S4 tetrahedra, corners with five equivalent Fe(3)S4 tetrahedra, edges with two equivalent Na(1)S6 octahedra, edges with four equivalent Na(2)S6 octahedra,  an edgeedge with one Fe(1)S4 tetrahedra,  an edgeedge with one Fe(3)S4 tetrahedra, and edges with two equivalent Fe(2)S4 tetrahedra. The Na(1)-S(2) bond length is 2.88 Å. The Na(1)-S(4) bond length is 2.96 Å. Both Na(1)-S(1) bond lengths are 2.79 Å. Both Na(1)-S(3) bond lengths are 2.90 Å. In the second Na site, Na(2) is bonded to one S(1), one S(3), two equivalent S(2), and two equivalent S(4) atoms to form distorted NaS6 octahedra that share  a cornercorner with one Fe(1)S4 tetrahedra,  a cornercorner with one Fe(3)S4 tetrahedra, corners with five equivalent Fe(2)S4 tetrahedra, edges with two equivalent Na(2)S6 octahedra, edges with four equivalent Na(1)S6 octahedra,  an edgeedge with one Fe(2)S4 tetrahedra, edges with two equivalent Fe(1)S4 tetrahedra, and edges with two equivalent Fe(3)S4 tetrahedra. The Na(2)-S(1) bond length is 2.79 Å. The Na(2)-S(3) bond length is 2.96 Å. Both Na(2)-S(2) bond lengths are 2.82 Å. Both Na(2)-S(4) bond lengths are 2.89 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form FeS4 tetrahedra that share  a cornercorner with one Na(2)S6 octahedra, corners with five equivalent Na(1)S6 octahedra, corners with two equivalent Fe(1)S4 tetrahedra,  an edgeedge with one Na(1)S6 octahedra, edges with two equivalent Na(2)S6 octahedra,  an edgeedge with one Fe(2)S4 tetrahedra, and edges with two equivalent Fe(3)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-51°. The Fe(1)-S(2) bond length is 2.15 Å. The Fe(1)-S(3) bond length is 2.17 Å. Both Fe(1)-S(1) bond lengths are 2.19 Å. In the second Fe site, Fe(2) is bonded to one S(2), one S(3), and two equivalent S(4) atoms to form FeS4 tetrahedra that share  a cornercorner with one Na(1)S6 octahedra, corners with five equivalent Na(2)S6 octahedra, corners with two equivalent Fe(2)S4 tetrahedra, corners with four equivalent Fe(3)S4 tetrahedra,  an edgeedge with one Na(2)S6 octahedra, edges with two equivalent Na(1)S6 octahedra, and  an edgeedge with one Fe(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-54°. The Fe(2)-S(2) bond length is 2.15 Å. The Fe(2)-S(3) bond length is 2.21 Å. Both Fe(2)-S(4) bond lengths are 2.17 Å. In the third Fe site, Fe(3) is bonded to one S(1), one S(4), and two equivalent S(3) atoms to form FeS4 tetrahedra that share  a cornercorner with one Na(2)S6 octahedra, corners with five equivalent Na(1)S6 octahedra, corners with two equivalent Fe(3)S4 tetrahedra, corners with four equivalent Fe(2)S4 tetrahedra,  an edgeedge with one Na(1)S6 octahedra, edges with two equivalent Na(2)S6 octahedra, and edges with two equivalent Fe(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 27-52°. The Fe(3)-S(1) bond length is 2.18 Å. The Fe(3)-S(4) bond length is 2.23 Å. Both Fe(3)-S(3) bond lengths are 2.28 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded to one Na(2), two equivalent Na(1), one Fe(3), and two equivalent Fe(1) atoms to form distorted SNa3Fe3 octahedra that share corners with two equivalent S(2)Na3Fe2 square pyramids, edges with two equivalent S(1)Na3Fe3 octahedra, and edges with two equivalent S(2)Na3Fe2 square pyramids. In the second S site, S(2) is bonded to one Na(1), two equivalent Na(2), one Fe(1), and one Fe(2) atom to form distorted SNa3Fe2 square pyramids that share corners with two equivalent S(1)Na3Fe3 octahedra, corners with two equivalent S(2)Na3Fe2 square pyramids, and edges with two equivalent S(1)Na3Fe3 octahedra. The corner-sharing octahedral tilt angles are 94°. In the third S site, S(3) is bonded in a 7-coordinate geometry to one Na(2), two equivalent Na(1), one Fe(1), one Fe(2), and two equivalent Fe(3) atoms. In the fourth S site, S(4) is bonded in a 6-coordinate geometry to one Na(1), two equivalent Na(2), one Fe(3), and two equivalent Fe(2) atoms.