HgCr2S4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one S(3), two equivalent S(4), and three equivalent S(2) atoms to form a mixture of edge and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles range from 55-56°. In the second Cr site, Cr(2) is bonded to one S(2), one S(4), two equivalent S(1), and two equivalent S(3) atoms to form a mixture of edge and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles range from 55-56°. Hg(1) is bonded in a 3-coordinate geometry to one S(1) and two equivalent S(3) atoms. There are four inequivalent S sites. In the first S site, S(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cr(2) and one Hg(1) atom. In the second S site, S(2) is bonded in a rectangular see-saw-like geometry to one Cr(2) and three equivalent Cr(1) atoms. In the third S site, S(3) is bonded to one Cr(1), two equivalent Cr(2), and two equivalent Hg(1) atoms to form distorted edge-sharing SCr3Hg2 trigonal bipyramids. In the fourth S site, S(4) is bonded in a distorted trigonal non-coplanar geometry to one Cr(2) and two equivalent Cr(1) atoms.
HgCr2S4 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one S(3), two equivalent S(4), and three equivalent S(2) atoms to form a mixture of edge and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles range from 55-56°. The Cr(1)-S(3) bond length is 2.46 Å. Both Cr(1)-S(4) bond lengths are 2.37 Å. There are two shorter (2.44 Å) and one longer (2.47 Å) Cr(1)-S(2) bond length. In the second Cr site, Cr(2) is bonded to one S(2), one S(4), two equivalent S(1), and two equivalent S(3) atoms to form a mixture of edge and corner-sharing CrS6 octahedra. The corner-sharing octahedral tilt angles range from 55-56°. The Cr(2)-S(2) bond length is 2.63 Å. The Cr(2)-S(4) bond length is 2.36 Å. Both Cr(2)-S(1) bond lengths are 2.39 Å. Both Cr(2)-S(3) bond lengths are 2.50 Å. Hg(1) is bonded in a 3-coordinate geometry to one S(1) and two equivalent S(3) atoms. The Hg(1)-S(1) bond length is 2.51 Å. Both Hg(1)-S(3) bond lengths are 2.67 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cr(2) and one Hg(1) atom. In the second S site, S(2) is bonded in a rectangular see-saw-like geometry to one Cr(2) and three equivalent Cr(1) atoms. In the third S site, S(3) is bonded to one Cr(1), two equivalent Cr(2), and two equivalent Hg(1) atoms to form distorted edge-sharing SCr3Hg2 trigonal bipyramids. In the fourth S site, S(4) is bonded in a distorted trigonal non-coplanar geometry to one Cr(2) and two equivalent Cr(1) atoms.