Zr21S8 crystallizes in the tetragonal I4/m space group. There are six inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a square co-planar geometry to four equivalent S(1) atoms. In the second Zr site, Zr(2) is bonded in a single-bond geometry to one S(2) atom. In the third Zr site, Zr(3) is bonded in a 3-coordinate geometry to one S(1) and two equivalent S(2) atoms. In the fourth Zr site, Zr(4) is bonded in an L-shaped geometry to two equivalent S(2) atoms. In the fifth Zr site, Zr(5) is bonded in a distorted rectangular see-saw-like geometry to one S(1) and three equivalent S(2) atoms. In the sixth Zr site, Zr(6) is bonded in a distorted rectangular see-saw-like geometry to four equivalent S(1) atoms. There are two inequivalent S sites. In the first S site, S(1) is bonded to one Zr(1), one Zr(3), one Zr(5), and four equivalent Zr(6) atoms to form a mixture of distorted edge, face, and corner-sharing SZr7 pentagonal bipyramids. In the second S site, S(2) is bonded in a 8-coordinate geometry to one Zr(2), two equivalent Zr(3), two equivalent Zr(4), and three equivalent Zr(5) atoms.
Zr21S8 crystallizes in the tetragonal I4/m space group. There are six inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a square co-planar geometry to four equivalent S(1) atoms. All Zr(1)-S(1) bond lengths are 2.68 Å. In the second Zr site, Zr(2) is bonded in a single-bond geometry to one S(2) atom. The Zr(2)-S(2) bond length is 2.80 Å. In the third Zr site, Zr(3) is bonded in a 3-coordinate geometry to one S(1) and two equivalent S(2) atoms. The Zr(3)-S(1) bond length is 2.60 Å. Both Zr(3)-S(2) bond lengths are 2.71 Å. In the fourth Zr site, Zr(4) is bonded in an L-shaped geometry to two equivalent S(2) atoms. Both Zr(4)-S(2) bond lengths are 2.66 Å. In the fifth Zr site, Zr(5) is bonded in a distorted rectangular see-saw-like geometry to one S(1) and three equivalent S(2) atoms. The Zr(5)-S(1) bond length is 2.63 Å. There are two shorter (2.71 Å) and one longer (2.78 Å) Zr(5)-S(2) bond length. In the sixth Zr site, Zr(6) is bonded in a distorted rectangular see-saw-like geometry to four equivalent S(1) atoms. There are two shorter (2.67 Å) and two longer (2.69 Å) Zr(6)-S(1) bond lengths. There are two inequivalent S sites. In the first S site, S(1) is bonded to one Zr(1), one Zr(3), one Zr(5), and four equivalent Zr(6) atoms to form a mixture of distorted edge, face, and corner-sharing SZr7 pentagonal bipyramids. In the second S site, S(2) is bonded in a 8-coordinate geometry to one Zr(2), two equivalent Zr(3), two equivalent Zr(4), and three equivalent Zr(5) atoms.