Zr2FeS4 crystallizes in the monoclinic Cm space group. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded to one S(1), one S(3), two equivalent S(2), and two equivalent S(4) atoms to form ZrS6 octahedra that share corners with five equivalent Fe(1)S4 tetrahedra, edges with two equivalent Zr(1)S6 octahedra, edges with four equivalent Zr(2)S6 octahedra, and  an edgeedge with one Fe(1)S4 tetrahedra. In the second Zr site, Zr(2) is bonded to one S(2), one S(4), two equivalent S(1), and two equivalent S(3) atoms to form distorted ZrS6 octahedra that share  a cornercorner with one Fe(1)S4 tetrahedra, edges with two equivalent Zr(2)S6 octahedra, edges with four equivalent Zr(1)S6 octahedra, and edges with two equivalent Fe(1)S4 tetrahedra. Fe(1) 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 Zr(2)S6 octahedra, corners with five equivalent Zr(1)S6 octahedra, corners with two equivalent Fe(1)S4 tetrahedra,  an edgeedge with one Zr(1)S6 octahedra, and edges with two equivalent Zr(2)S6 octahedra. The corner-sharing octahedral tilt angles range from 18-56°. There are four inequivalent S sites. In the first S site, S(1) is bonded in a distorted T-shaped geometry to one Zr(1) and two equivalent Zr(2) atoms. In the second S site, S(2) is bonded in a rectangular see-saw-like geometry to one Zr(2), two equivalent Zr(1), and one Fe(1) atom. In the third S site, S(3) is bonded in a rectangular see-saw-like geometry to one Zr(1), two equivalent Zr(2), and one Fe(1) atom. In the fourth S site, S(4) is bonded to one Zr(2), two equivalent Zr(1), and two equivalent Fe(1) atoms to form distorted edge-sharing SZr3Fe2 square pyramids.
Zr2FeS4 crystallizes in the monoclinic Cm space group. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded to one S(1), one S(3), two equivalent S(2), and two equivalent S(4) atoms to form ZrS6 octahedra that share corners with five equivalent Fe(1)S4 tetrahedra, edges with two equivalent Zr(1)S6 octahedra, edges with four equivalent Zr(2)S6 octahedra, and  an edgeedge with one Fe(1)S4 tetrahedra. The Zr(1)-S(1) bond length is 2.52 Å. The Zr(1)-S(3) bond length is 2.60 Å. Both Zr(1)-S(2) bond lengths are 2.60 Å. Both Zr(1)-S(4) bond lengths are 2.60 Å. In the second Zr site, Zr(2) is bonded to one S(2), one S(4), two equivalent S(1), and two equivalent S(3) atoms to form distorted ZrS6 octahedra that share  a cornercorner with one Fe(1)S4 tetrahedra, edges with two equivalent Zr(2)S6 octahedra, edges with four equivalent Zr(1)S6 octahedra, and edges with two equivalent Fe(1)S4 tetrahedra. The Zr(2)-S(2) bond length is 2.67 Å. The Zr(2)-S(4) bond length is 2.59 Å. Both Zr(2)-S(1) bond lengths are 2.59 Å. Both Zr(2)-S(3) bond lengths are 2.61 Å. Fe(1) 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 Zr(2)S6 octahedra, corners with five equivalent Zr(1)S6 octahedra, corners with two equivalent Fe(1)S4 tetrahedra,  an edgeedge with one Zr(1)S6 octahedra, and edges with two equivalent Zr(2)S6 octahedra. The corner-sharing octahedral tilt angles range from 18-56°. The Fe(1)-S(2) bond length is 2.34 Å. The Fe(1)-S(3) bond length is 2.26 Å. Both Fe(1)-S(4) bond lengths are 2.24 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded in a distorted T-shaped geometry to one Zr(1) and two equivalent Zr(2) atoms. In the second S site, S(2) is bonded in a rectangular see-saw-like geometry to one Zr(2), two equivalent Zr(1), and one Fe(1) atom. In the third S site, S(3) is bonded in a rectangular see-saw-like geometry to one Zr(1), two equivalent Zr(2), and one Fe(1) atom. In the fourth S site, S(4) is bonded to one Zr(2), two equivalent Zr(1), and two equivalent Fe(1) atoms to form distorted edge-sharing SZr3Fe2 square pyramids.