Y6Fe(SiS7)2 crystallizes in the trigonal P3 space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 8-coordinate geometry to one S(1), one S(6), two equivalent S(3), two equivalent S(4), and two equivalent S(5) atoms. In the second Y site, Y(2) is bonded in a 8-coordinate geometry to one S(2), one S(5), two equivalent S(3), two equivalent S(4), and two equivalent S(6) atoms. Fe(1) is bonded in an octahedral geometry to three equivalent S(3) and three equivalent S(4) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a tetrahedral geometry to one S(1) and three equivalent S(5) atoms. In the second Si site, Si(2) is bonded in a tetrahedral geometry to one S(2) and three equivalent S(6) atoms. There are six inequivalent S sites. In the first S site, S(1) is bonded to three equivalent Y(1) and one Si(1) atom to form corner-sharing SY3Si tetrahedra. In the second S site, S(2) is bonded to three equivalent Y(2) and one Si(2) atom to form distorted corner-sharing SY3Si tetrahedra. In the third S site, S(3) is bonded to two equivalent Y(1), two equivalent Y(2), and one Fe(1) atom to form distorted SY4Fe trigonal bipyramids that share corners with two equivalent S(1)Y3Si tetrahedra, corners with two equivalent S(2)Y3Si tetrahedra,  a cornercorner with one S(4)Y4Fe trigonal bipyramid, corners with two equivalent S(3)Y4Fe trigonal bipyramids, edges with two equivalent S(3)Y4Fe trigonal bipyramids, edges with two equivalent S(4)Y4Fe trigonal bipyramids, and faces with two equivalent S(4)Y4Fe trigonal bipyramids. In the fourth S site, S(4) is bonded to two equivalent Y(1), two equivalent Y(2), and one Fe(1) atom to form distorted SY4Fe trigonal bipyramids that share corners with two equivalent S(1)Y3Si tetrahedra, corners with two equivalent S(2)Y3Si tetrahedra,  a cornercorner with one S(3)Y4Fe trigonal bipyramid, corners with two equivalent S(4)Y4Fe trigonal bipyramids, edges with two equivalent S(3)Y4Fe trigonal bipyramids, edges with two equivalent S(4)Y4Fe trigonal bipyramids, and faces with two equivalent S(3)Y4Fe trigonal bipyramids. In the fifth S site, S(5) is bonded in a distorted rectangular see-saw-like geometry to one Y(2), two equivalent Y(1), and one Si(1) atom. In the sixth S site, S(6) is bonded in a distorted rectangular see-saw-like geometry to one Y(1), two equivalent Y(2), and one Si(2) atom.
Y6Fe(SiS7)2 crystallizes in the trigonal P3 space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 8-coordinate geometry to one S(1), one S(6), two equivalent S(3), two equivalent S(4), and two equivalent S(5) atoms. The Y(1)-S(1) bond length is 2.97 Å. The Y(1)-S(6) bond length is 2.93 Å. There is one shorter (2.83 Å) and one longer (3.14 Å) Y(1)-S(3) bond length. Both Y(1)-S(4) bond lengths are 2.74 Å. There is one shorter (2.82 Å) and one longer (2.90 Å) Y(1)-S(5) bond length. In the second Y site, Y(2) is bonded in a 8-coordinate geometry to one S(2), one S(5), two equivalent S(3), two equivalent S(4), and two equivalent S(6) atoms. The Y(2)-S(2) bond length is 2.98 Å. The Y(2)-S(5) bond length is 2.93 Å. There is one shorter (2.73 Å) and one longer (2.74 Å) Y(2)-S(3) bond length. There is one shorter (2.96 Å) and one longer (2.99 Å) Y(2)-S(4) bond length. There is one shorter (2.79 Å) and one longer (2.89 Å) Y(2)-S(6) bond length. Fe(1) is bonded in an octahedral geometry to three equivalent S(3) and three equivalent S(4) atoms. All Fe(1)-S(3) bond lengths are 2.52 Å. All Fe(1)-S(4) bond lengths are 2.53 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a tetrahedral geometry to one S(1) and three equivalent S(5) atoms. The Si(1)-S(1) bond length is 2.10 Å. All Si(1)-S(5) bond lengths are 2.14 Å. In the second Si site, Si(2) is bonded in a tetrahedral geometry to one S(2) and three equivalent S(6) atoms. The Si(2)-S(2) bond length is 2.10 Å. All Si(2)-S(6) bond lengths are 2.14 Å. There are six inequivalent S sites. In the first S site, S(1) is bonded to three equivalent Y(1) and one Si(1) atom to form corner-sharing SY3Si tetrahedra. In the second S site, S(2) is bonded to three equivalent Y(2) and one Si(2) atom to form distorted corner-sharing SY3Si tetrahedra. In the third S site, S(3) is bonded to two equivalent Y(1), two equivalent Y(2), and one Fe(1) atom to form distorted SY4Fe trigonal bipyramids that share corners with two equivalent S(1)Y3Si tetrahedra, corners with two equivalent S(2)Y3Si tetrahedra,  a cornercorner with one S(4)Y4Fe trigonal bipyramid, corners with two equivalent S(3)Y4Fe trigonal bipyramids, edges with two equivalent S(3)Y4Fe trigonal bipyramids, edges with two equivalent S(4)Y4Fe trigonal bipyramids, and faces with two equivalent S(4)Y4Fe trigonal bipyramids. In the fourth S site, S(4) is bonded to two equivalent Y(1), two equivalent Y(2), and one Fe(1) atom to form distorted SY4Fe trigonal bipyramids that share corners with two equivalent S(1)Y3Si tetrahedra, corners with two equivalent S(2)Y3Si tetrahedra,  a cornercorner with one S(3)Y4Fe trigonal bipyramid, corners with two equivalent S(4)Y4Fe trigonal bipyramids, edges with two equivalent S(3)Y4Fe trigonal bipyramids, edges with two equivalent S(4)Y4Fe trigonal bipyramids, and faces with two equivalent S(3)Y4Fe trigonal bipyramids. In the fifth S site, S(5) is bonded in a distorted rectangular see-saw-like geometry to one Y(2), two equivalent Y(1), and one Si(1) atom. In the sixth S site, S(6) is bonded in a distorted rectangular see-saw-like geometry to one Y(1), two equivalent Y(2), and one Si(2) atom.