MgTiNbS4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one S(1), one S(2), two equivalent S(3), and two equivalent S(4) atoms to form MgS6 octahedra that share corners with six equivalent Ti(1)S6 octahedra, corners with six equivalent Nb(1)S6 octahedra, edges with two equivalent Mg(1)S6 octahedra,  a faceface with one Ti(1)S6 octahedra, and  a faceface with one Nb(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. Ti(1) is bonded to one S(1), one S(4), two equivalent S(2), and two equivalent S(3) atoms to form distorted TiS6 octahedra that share corners with six equivalent Mg(1)S6 octahedra, edges with two equivalent Ti(1)S6 octahedra, edges with four equivalent Nb(1)S6 octahedra, and  a faceface with one Mg(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. Nb(1) is bonded to one S(2), one S(3), two equivalent S(1), and two equivalent S(4) atoms to form distorted NbS6 octahedra that share corners with six equivalent Mg(1)S6 octahedra, edges with two equivalent Nb(1)S6 octahedra, edges with four equivalent Ti(1)S6 octahedra, and  a faceface with one Mg(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 51-53°. There are four inequivalent S sites. In the first S site, S(1) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Ti(1), and two equivalent Nb(1) atoms. In the second S site, S(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Ti(1), and one Nb(1) atom. In the third S site, S(3) is bonded to two equivalent Mg(1), two equivalent Ti(1), and one Nb(1) atom to form distorted SMg2Ti2Nb trigonal bipyramids that share corners with two equivalent S(4)Mg2TiNb2 trigonal bipyramids, edges with two equivalent S(3)Mg2Ti2Nb trigonal bipyramids, and edges with three equivalent S(4)Mg2TiNb2 trigonal bipyramids. In the fourth S site, S(4) is bonded to two equivalent Mg(1), one Ti(1), and two equivalent Nb(1) atoms to form distorted SMg2TiNb2 trigonal bipyramids that share corners with two equivalent S(3)Mg2Ti2Nb trigonal bipyramids, edges with two equivalent S(4)Mg2TiNb2 trigonal bipyramids, and edges with three equivalent S(3)Mg2Ti2Nb trigonal bipyramids.
MgTiNbS4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one S(1), one S(2), two equivalent S(3), and two equivalent S(4) atoms to form MgS6 octahedra that share corners with six equivalent Ti(1)S6 octahedra, corners with six equivalent Nb(1)S6 octahedra, edges with two equivalent Mg(1)S6 octahedra,  a faceface with one Ti(1)S6 octahedra, and  a faceface with one Nb(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. The Mg(1)-S(1) bond length is 2.58 Å. The Mg(1)-S(2) bond length is 2.61 Å. There is one shorter (2.58 Å) and one longer (2.59 Å) Mg(1)-S(3) bond length. There is one shorter (2.59 Å) and one longer (2.60 Å) Mg(1)-S(4) bond length. Ti(1) is bonded to one S(1), one S(4), two equivalent S(2), and two equivalent S(3) atoms to form distorted TiS6 octahedra that share corners with six equivalent Mg(1)S6 octahedra, edges with two equivalent Ti(1)S6 octahedra, edges with four equivalent Nb(1)S6 octahedra, and  a faceface with one Mg(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 49-53°. The Ti(1)-S(1) bond length is 2.44 Å. The Ti(1)-S(4) bond length is 2.61 Å. Both Ti(1)-S(2) bond lengths are 2.42 Å. Both Ti(1)-S(3) bond lengths are 2.56 Å. Nb(1) is bonded to one S(2), one S(3), two equivalent S(1), and two equivalent S(4) atoms to form distorted NbS6 octahedra that share corners with six equivalent Mg(1)S6 octahedra, edges with two equivalent Nb(1)S6 octahedra, edges with four equivalent Ti(1)S6 octahedra, and  a faceface with one Mg(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 51-53°. The Nb(1)-S(2) bond length is 2.46 Å. The Nb(1)-S(3) bond length is 2.63 Å. Both Nb(1)-S(1) bond lengths are 2.47 Å. Both Nb(1)-S(4) bond lengths are 2.59 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Ti(1), and two equivalent Nb(1) atoms. In the second S site, S(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Ti(1), and one Nb(1) atom. In the third S site, S(3) is bonded to two equivalent Mg(1), two equivalent Ti(1), and one Nb(1) atom to form distorted SMg2Ti2Nb trigonal bipyramids that share corners with two equivalent S(4)Mg2TiNb2 trigonal bipyramids, edges with two equivalent S(3)Mg2Ti2Nb trigonal bipyramids, and edges with three equivalent S(4)Mg2TiNb2 trigonal bipyramids. In the fourth S site, S(4) is bonded to two equivalent Mg(1), one Ti(1), and two equivalent Nb(1) atoms to form distorted SMg2TiNb2 trigonal bipyramids that share corners with two equivalent S(3)Mg2Ti2Nb trigonal bipyramids, edges with two equivalent S(4)Mg2TiNb2 trigonal bipyramids, and edges with three equivalent S(3)Mg2Ti2Nb trigonal bipyramids.