Fe7S8 crystallizes in the trigonal P3_1 space group. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one S(1), one S(3), one S(4), one S(5), one S(6), and one S(7) atom to form a mixture of face, corner, and edge-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 55-56°. In the second Fe site, Fe(2) is bonded to one S(2), one S(3), one S(4), one S(5), one S(6), and one S(8) atom to form a mixture of distorted face, corner, and edge-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 54-56°. In the third Fe site, Fe(3) is bonded to one S(1), one S(2), one S(4), one S(5), one S(7), and one S(8) atom to form a mixture of distorted corner and edge-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 48-57°. In the fourth Fe site, Fe(4) is bonded in a 6-coordinate geometry to one S(1), one S(2), one S(3), one S(6), one S(7), and one S(8) atom. In the fifth Fe site, Fe(5) is bonded to one S(1), one S(3), one S(4), one S(5), one S(6), and one S(8) atom to form a mixture of face and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 48-57°. In the sixth Fe site, Fe(6) is bonded in a 6-coordinate geometry to one S(1), one S(2), one S(4), one S(5), one S(7), and one S(8) atom. In the seventh Fe site, Fe(7) is bonded in a 6-coordinate geometry to one S(2), one S(3), one S(4), one S(6), one S(7), and one S(8) atom. There are eight inequivalent S sites. In the first S site, S(5) is bonded in a 5-coordinate geometry to one Fe(1), one Fe(2), one Fe(3), one Fe(5), and one Fe(6) atom. In the second S site, S(6) is bonded in a 5-coordinate geometry to one Fe(1), one Fe(2), one Fe(4), one Fe(5), and one Fe(7) atom. In the third S site, S(7) is bonded in a distorted pentagonal planar geometry to one Fe(1), one Fe(3), one Fe(4), one Fe(6), and one Fe(7) atom. In the fourth S site, S(8) is bonded in a 6-coordinate geometry to one Fe(2), one Fe(3), one Fe(4), one Fe(5), one Fe(6), and one Fe(7) atom. In the fifth S site, S(1) is bonded to one Fe(1), one Fe(3), one Fe(4), one Fe(5), and one Fe(6) atom to form a mixture of distorted corner and edge-sharing SFe5 trigonal bipyramids. In the sixth S site, S(2) is bonded in a distorted pentagonal planar geometry to one Fe(2), one Fe(3), one Fe(4), one Fe(6), and one Fe(7) atom. In the seventh S site, S(3) is bonded to one Fe(1), one Fe(2), one Fe(4), one Fe(5), and one Fe(7) atom to form a mixture of distorted corner and edge-sharing SFe5 trigonal bipyramids. In the eighth S site, S(4) is bonded in a 6-coordinate geometry to one Fe(1), one Fe(2), one Fe(3), one Fe(5), one Fe(6), and one Fe(7) atom.
Fe7S8 crystallizes in the trigonal P3_1 space group. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one S(1), one S(3), one S(4), one S(5), one S(6), and one S(7) atom to form a mixture of face, corner, and edge-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 55-56°. The Fe(1)-S(1) bond length is 2.30 Å. The Fe(1)-S(3) bond length is 2.30 Å. The Fe(1)-S(4) bond length is 2.39 Å. The Fe(1)-S(5) bond length is 2.23 Å. The Fe(1)-S(6) bond length is 2.25 Å. The Fe(1)-S(7) bond length is 2.26 Å. In the second Fe site, Fe(2) is bonded to one S(2), one S(3), one S(4), one S(5), one S(6), and one S(8) atom to form a mixture of distorted face, corner, and edge-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 54-56°. The Fe(2)-S(2) bond length is 2.19 Å. The Fe(2)-S(3) bond length is 2.40 Å. The Fe(2)-S(4) bond length is 2.43 Å. The Fe(2)-S(5) bond length is 2.25 Å. The Fe(2)-S(6) bond length is 2.27 Å. The Fe(2)-S(8) bond length is 2.39 Å. In the third Fe site, Fe(3) is bonded to one S(1), one S(2), one S(4), one S(5), one S(7), and one S(8) atom to form a mixture of distorted corner and edge-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 48-57°. The Fe(3)-S(1) bond length is 2.41 Å. The Fe(3)-S(2) bond length is 2.19 Å. The Fe(3)-S(4) bond length is 2.43 Å. The Fe(3)-S(5) bond length is 2.29 Å. The Fe(3)-S(7) bond length is 2.31 Å. The Fe(3)-S(8) bond length is 2.45 Å. In the fourth Fe site, Fe(4) is bonded in a 6-coordinate geometry to one S(1), one S(2), one S(3), one S(6), one S(7), and one S(8) atom. The Fe(4)-S(1) bond length is 2.34 Å. The Fe(4)-S(2) bond length is 2.18 Å. The Fe(4)-S(3) bond length is 2.35 Å. The Fe(4)-S(6) bond length is 2.31 Å. The Fe(4)-S(7) bond length is 2.32 Å. The Fe(4)-S(8) bond length is 2.60 Å. In the fifth Fe site, Fe(5) is bonded to one S(1), one S(3), one S(4), one S(5), one S(6), and one S(8) atom to form a mixture of face and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 48-57°. The Fe(5)-S(1) bond length is 2.28 Å. The Fe(5)-S(3) bond length is 2.29 Å. The Fe(5)-S(4) bond length is 2.35 Å. The Fe(5)-S(5) bond length is 2.39 Å. The Fe(5)-S(6) bond length is 2.46 Å. The Fe(5)-S(8) bond length is 2.31 Å. In the sixth Fe site, Fe(6) is bonded in a 6-coordinate geometry to one S(1), one S(2), one S(4), one S(5), one S(7), and one S(8) atom. The Fe(6)-S(1) bond length is 2.26 Å. The Fe(6)-S(2) bond length is 2.23 Å. The Fe(6)-S(4) bond length is 2.80 Å. The Fe(6)-S(5) bond length is 2.39 Å. The Fe(6)-S(7) bond length is 2.35 Å. The Fe(6)-S(8) bond length is 2.24 Å. In the seventh Fe site, Fe(7) is bonded in a 6-coordinate geometry to one S(2), one S(3), one S(4), one S(6), one S(7), and one S(8) atom. The Fe(7)-S(2) bond length is 2.24 Å. The Fe(7)-S(3) bond length is 2.30 Å. The Fe(7)-S(4) bond length is 2.86 Å. The Fe(7)-S(6) bond length is 2.37 Å. The Fe(7)-S(7) bond length is 2.32 Å. The Fe(7)-S(8) bond length is 2.20 Å. There are eight inequivalent S sites. In the first S site, S(5) is bonded in a 5-coordinate geometry to one Fe(1), one Fe(2), one Fe(3), one Fe(5), and one Fe(6) atom. In the second S site, S(6) is bonded in a 5-coordinate geometry to one Fe(1), one Fe(2), one Fe(4), one Fe(5), and one Fe(7) atom. In the third S site, S(7) is bonded in a distorted pentagonal planar geometry to one Fe(1), one Fe(3), one Fe(4), one Fe(6), and one Fe(7) atom. In the fourth S site, S(8) is bonded in a 6-coordinate geometry to one Fe(2), one Fe(3), one Fe(4), one Fe(5), one Fe(6), and one Fe(7) atom. In the fifth S site, S(1) is bonded to one Fe(1), one Fe(3), one Fe(4), one Fe(5), and one Fe(6) atom to form a mixture of distorted corner and edge-sharing SFe5 trigonal bipyramids. In the sixth S site, S(2) is bonded in a distorted pentagonal planar geometry to one Fe(2), one Fe(3), one Fe(4), one Fe(6), and one Fe(7) atom. In the seventh S site, S(3) is bonded to one Fe(1), one Fe(2), one Fe(4), one Fe(5), and one Fe(7) atom to form a mixture of distorted corner and edge-sharing SFe5 trigonal bipyramids. In the eighth S site, S(4) is bonded in a 6-coordinate geometry to one Fe(1), one Fe(2), one Fe(3), one Fe(5), one Fe(6), and one Fe(7) atom.