Mg2TiNi3S8 is Spinel-derived structured and crystallizes in the triclinic P-1 space group. Mg(1) is bonded to one S(1), one S(2), one S(3), and one S(4) atom to form MgS4 tetrahedra that share corners with three equivalent Ti(1)S6 octahedra, corners with three equivalent Ni(1)S6 octahedra, corners with three equivalent Ni(2)S6 octahedra, and corners with three equivalent Ni(3)S6 octahedra. The corner-sharing octahedral tilt angles range from 58-61°. Ti(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(4) atoms to form TiS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Ni(1)S6 octahedra, edges with two equivalent Ni(2)S6 octahedra, and edges with two equivalent Ni(3)S6 octahedra. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent S(2), two equivalent S(3), and two equivalent S(4) atoms to form NiS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Ti(1)S6 octahedra, edges with two equivalent Ni(2)S6 octahedra, and edges with two equivalent Ni(3)S6 octahedra. In the second Ni site, Ni(2) is bonded to two equivalent S(1), two equivalent S(3), and two equivalent S(4) atoms to form NiS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Ti(1)S6 octahedra, edges with two equivalent Ni(1)S6 octahedra, and edges with two equivalent Ni(3)S6 octahedra. In the third Ni site, Ni(3) 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 Ti(1)S6 octahedra, edges with two equivalent Ni(1)S6 octahedra, and edges with two equivalent Ni(2)S6 octahedra. There are four inequivalent S sites. In the first S site, S(1) is bonded to one Mg(1), one Ti(1), one Ni(2), and one Ni(3) atom to form distorted SMgTiNi2 trigonal pyramids that share corners with three equivalent S(3)MgNi3 tetrahedra, corners with three equivalent S(1)MgTiNi2 trigonal pyramids, corners with three equivalent S(2)MgTiNi2 trigonal pyramids, corners with three equivalent S(4)MgTiNi2 trigonal pyramids,  an edgeedge with one S(3)MgNi3 tetrahedra,  an edgeedge with one S(2)MgTiNi2 trigonal pyramid, and  an edgeedge with one S(4)MgTiNi2 trigonal pyramid. In the second S site, S(2) is bonded to one Mg(1), one Ti(1), one Ni(1), and one Ni(3) atom to form distorted SMgTiNi2 trigonal pyramids that share corners with three equivalent S(3)MgNi3 tetrahedra, corners with three equivalent S(1)MgTiNi2 trigonal pyramids, corners with three equivalent S(2)MgTiNi2 trigonal pyramids, corners with three equivalent S(4)MgTiNi2 trigonal pyramids,  an edgeedge with one S(3)MgNi3 tetrahedra,  an edgeedge with one S(1)MgTiNi2 trigonal pyramid, and  an edgeedge with one S(4)MgTiNi2 trigonal pyramid. In the third S site, S(3) is bonded to one Mg(1), one Ni(1), one Ni(2), and one Ni(3) atom to form distorted SMgNi3 tetrahedra that share corners with three equivalent S(3)MgNi3 tetrahedra, corners with three equivalent S(1)MgTiNi2 trigonal pyramids, corners with three equivalent S(2)MgTiNi2 trigonal pyramids, corners with three equivalent S(4)MgTiNi2 trigonal pyramids,  an edgeedge with one S(1)MgTiNi2 trigonal pyramid,  an edgeedge with one S(2)MgTiNi2 trigonal pyramid, and  an edgeedge with one S(4)MgTiNi2 trigonal pyramid. In the fourth S site, S(4) is bonded to one Mg(1), one Ti(1), one Ni(1), and one Ni(2) atom to form distorted SMgTiNi2 trigonal pyramids that share corners with three equivalent S(3)MgNi3 tetrahedra, corners with three equivalent S(1)MgTiNi2 trigonal pyramids, corners with three equivalent S(2)MgTiNi2 trigonal pyramids, corners with three equivalent S(4)MgTiNi2 trigonal pyramids,  an edgeedge with one S(3)MgNi3 tetrahedra,  an edgeedge with one S(1)MgTiNi2 trigonal pyramid, and  an edgeedge with one S(2)MgTiNi2 trigonal pyramid.
Mg2TiNi3S8 is Spinel-derived structured and crystallizes in the triclinic P-1 space group. Mg(1) is bonded to one S(1), one S(2), one S(3), and one S(4) atom to form MgS4 tetrahedra that share corners with three equivalent Ti(1)S6 octahedra, corners with three equivalent Ni(1)S6 octahedra, corners with three equivalent Ni(2)S6 octahedra, and corners with three equivalent Ni(3)S6 octahedra. The corner-sharing octahedral tilt angles range from 58-61°. The Mg(1)-S(1) bond length is 2.43 Å. The Mg(1)-S(2) bond length is 2.43 Å. The Mg(1)-S(3) bond length is 2.46 Å. The Mg(1)-S(4) bond length is 2.43 Å. Ti(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(4) atoms to form TiS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Ni(1)S6 octahedra, edges with two equivalent Ni(2)S6 octahedra, and edges with two equivalent Ni(3)S6 octahedra. Both Ti(1)-S(1) bond lengths are 2.44 Å. Both Ti(1)-S(2) bond lengths are 2.44 Å. Both Ti(1)-S(4) bond lengths are 2.44 Å. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent S(2), two equivalent S(3), and two equivalent S(4) atoms to form NiS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Ti(1)S6 octahedra, edges with two equivalent Ni(2)S6 octahedra, and edges with two equivalent Ni(3)S6 octahedra. Both Ni(1)-S(2) bond lengths are 2.35 Å. Both Ni(1)-S(3) bond lengths are 2.36 Å. Both Ni(1)-S(4) bond lengths are 2.35 Å. In the second Ni site, Ni(2) is bonded to two equivalent S(1), two equivalent S(3), and two equivalent S(4) atoms to form NiS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Ti(1)S6 octahedra, edges with two equivalent Ni(1)S6 octahedra, and edges with two equivalent Ni(3)S6 octahedra. Both Ni(2)-S(1) bond lengths are 2.35 Å. Both Ni(2)-S(3) bond lengths are 2.35 Å. Both Ni(2)-S(4) bond lengths are 2.36 Å. In the third Ni site, Ni(3) 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 Ti(1)S6 octahedra, edges with two equivalent Ni(1)S6 octahedra, and edges with two equivalent Ni(2)S6 octahedra. Both Ni(3)-S(1) bond lengths are 2.35 Å. Both Ni(3)-S(2) bond lengths are 2.36 Å. Both Ni(3)-S(3) bond lengths are 2.35 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded to one Mg(1), one Ti(1), one Ni(2), and one Ni(3) atom to form distorted SMgTiNi2 trigonal pyramids that share corners with three equivalent S(3)MgNi3 tetrahedra, corners with three equivalent S(1)MgTiNi2 trigonal pyramids, corners with three equivalent S(2)MgTiNi2 trigonal pyramids, corners with three equivalent S(4)MgTiNi2 trigonal pyramids,  an edgeedge with one S(3)MgNi3 tetrahedra,  an edgeedge with one S(2)MgTiNi2 trigonal pyramid, and  an edgeedge with one S(4)MgTiNi2 trigonal pyramid. In the second S site, S(2) is bonded to one Mg(1), one Ti(1), one Ni(1), and one Ni(3) atom to form distorted SMgTiNi2 trigonal pyramids that share corners with three equivalent S(3)MgNi3 tetrahedra, corners with three equivalent S(1)MgTiNi2 trigonal pyramids, corners with three equivalent S(2)MgTiNi2 trigonal pyramids, corners with three equivalent S(4)MgTiNi2 trigonal pyramids,  an edgeedge with one S(3)MgNi3 tetrahedra,  an edgeedge with one S(1)MgTiNi2 trigonal pyramid, and  an edgeedge with one S(4)MgTiNi2 trigonal pyramid. In the third S site, S(3) is bonded to one Mg(1), one Ni(1), one Ni(2), and one Ni(3) atom to form distorted SMgNi3 tetrahedra that share corners with three equivalent S(3)MgNi3 tetrahedra, corners with three equivalent S(1)MgTiNi2 trigonal pyramids, corners with three equivalent S(2)MgTiNi2 trigonal pyramids, corners with three equivalent S(4)MgTiNi2 trigonal pyramids,  an edgeedge with one S(1)MgTiNi2 trigonal pyramid,  an edgeedge with one S(2)MgTiNi2 trigonal pyramid, and  an edgeedge with one S(4)MgTiNi2 trigonal pyramid. In the fourth S site, S(4) is bonded to one Mg(1), one Ti(1), one Ni(1), and one Ni(2) atom to form distorted SMgTiNi2 trigonal pyramids that share corners with three equivalent S(3)MgNi3 tetrahedra, corners with three equivalent S(1)MgTiNi2 trigonal pyramids, corners with three equivalent S(2)MgTiNi2 trigonal pyramids, corners with three equivalent S(4)MgTiNi2 trigonal pyramids,  an edgeedge with one S(3)MgNi3 tetrahedra,  an edgeedge with one S(1)MgTiNi2 trigonal pyramid, and  an edgeedge with one S(2)MgTiNi2 trigonal pyramid.