Mg2CrNi3S8 is Spinel-derived structured and crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form MgS4 tetrahedra that share corners with three equivalent Cr(1)S6 octahedra, corners with three equivalent Ni(2)S6 octahedra, and corners with six equivalent Ni(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 59-61°. Cr(1) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form CrS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Ni(2)S6 octahedra, and edges with four equivalent Ni(1)S6 octahedra. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form NiS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Cr(1)S6 octahedra, edges with two equivalent Ni(1)S6 octahedra, and edges with two equivalent Ni(2)S6 octahedra. In the second Ni site, Ni(2) is bonded to two equivalent S(3) and four equivalent S(1) atoms to form NiS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Cr(1)S6 octahedra, and edges with four equivalent Ni(1)S6 octahedra. There are three inequivalent S sites. In the first S site, S(1) is bonded to one Mg(1), one Cr(1), one Ni(1), and one Ni(2) atom to form distorted SMgCrNi2 tetrahedra that share corners with three equivalent S(2)MgCrNi2 tetrahedra, corners with three equivalent S(3)MgNi3 tetrahedra, corners with six equivalent S(1)MgCrNi2 tetrahedra,  an edgeedge with one S(1)MgCrNi2 tetrahedra,  an edgeedge with one S(2)MgCrNi2 tetrahedra, and  an edgeedge with one S(3)MgNi3 tetrahedra. In the second S site, S(2) is bonded to one Mg(1), one Cr(1), and two equivalent Ni(1) atoms to form distorted SMgCrNi2 tetrahedra that share corners with three equivalent S(2)MgCrNi2 tetrahedra, corners with three equivalent S(3)MgNi3 tetrahedra, corners with six equivalent S(1)MgCrNi2 tetrahedra,  an edgeedge with one S(3)MgNi3 tetrahedra, and edges with two equivalent S(1)MgCrNi2 tetrahedra. In the third S site, S(3) is bonded to one Mg(1), one Ni(2), and two equivalent Ni(1) atoms to form distorted SMgNi3 tetrahedra that share corners with three equivalent S(2)MgCrNi2 tetrahedra, corners with three equivalent S(3)MgNi3 tetrahedra, corners with six equivalent S(1)MgCrNi2 tetrahedra,  an edgeedge with one S(2)MgCrNi2 tetrahedra, and edges with two equivalent S(1)MgCrNi2 tetrahedra.
Mg2CrNi3S8 is Spinel-derived structured and crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form MgS4 tetrahedra that share corners with three equivalent Cr(1)S6 octahedra, corners with three equivalent Ni(2)S6 octahedra, and corners with six equivalent Ni(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 59-61°. The Mg(1)-S(2) bond length is 2.44 Å. The Mg(1)-S(3) bond length is 2.45 Å. Both Mg(1)-S(1) bond lengths are 2.43 Å. Cr(1) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form CrS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Ni(2)S6 octahedra, and edges with four equivalent Ni(1)S6 octahedra. Both Cr(1)-S(2) bond lengths are 2.38 Å. All Cr(1)-S(1) bond lengths are 2.38 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form NiS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Cr(1)S6 octahedra, edges with two equivalent Ni(1)S6 octahedra, and edges with two equivalent Ni(2)S6 octahedra. Both Ni(1)-S(1) bond lengths are 2.35 Å. Both Ni(1)-S(2) bond lengths are 2.34 Å. Both Ni(1)-S(3) bond lengths are 2.34 Å. In the second Ni site, Ni(2) is bonded to two equivalent S(3) and four equivalent S(1) atoms to form NiS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Cr(1)S6 octahedra, and edges with four equivalent Ni(1)S6 octahedra. Both Ni(2)-S(3) bond lengths are 2.34 Å. All Ni(2)-S(1) bond lengths are 2.34 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded to one Mg(1), one Cr(1), one Ni(1), and one Ni(2) atom to form distorted SMgCrNi2 tetrahedra that share corners with three equivalent S(2)MgCrNi2 tetrahedra, corners with three equivalent S(3)MgNi3 tetrahedra, corners with six equivalent S(1)MgCrNi2 tetrahedra,  an edgeedge with one S(1)MgCrNi2 tetrahedra,  an edgeedge with one S(2)MgCrNi2 tetrahedra, and  an edgeedge with one S(3)MgNi3 tetrahedra. In the second S site, S(2) is bonded to one Mg(1), one Cr(1), and two equivalent Ni(1) atoms to form distorted SMgCrNi2 tetrahedra that share corners with three equivalent S(2)MgCrNi2 tetrahedra, corners with three equivalent S(3)MgNi3 tetrahedra, corners with six equivalent S(1)MgCrNi2 tetrahedra,  an edgeedge with one S(3)MgNi3 tetrahedra, and edges with two equivalent S(1)MgCrNi2 tetrahedra. In the third S site, S(3) is bonded to one Mg(1), one Ni(2), and two equivalent Ni(1) atoms to form distorted SMgNi3 tetrahedra that share corners with three equivalent S(2)MgCrNi2 tetrahedra, corners with three equivalent S(3)MgNi3 tetrahedra, corners with six equivalent S(1)MgCrNi2 tetrahedra,  an edgeedge with one S(2)MgCrNi2 tetrahedra, and edges with two equivalent S(1)MgCrNi2 tetrahedra.