Mg2Mo3FeS8 is Spinel-derived structured and crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to one S(1), one S(3), and two equivalent S(2) atoms to form MgS4 tetrahedra that share corners with three equivalent Mo(2)S6 octahedra, corners with three equivalent Fe(1)S6 octahedra, and corners with six equivalent Mo(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 57-60°. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form MoS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Mo(1)S6 octahedra, edges with two equivalent Mo(2)S6 octahedra, and edges with two equivalent Fe(1)S6 octahedra. In the second Mo site, Mo(2) is bonded to two equivalent S(1) and four equivalent S(2) atoms to form MoS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Fe(1)S6 octahedra, and edges with four equivalent Mo(1)S6 octahedra. Fe(1) is bonded to two equivalent S(3) and four equivalent S(2) atoms to form FeS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Mo(2)S6 octahedra, and edges with four equivalent Mo(1)S6 octahedra. There are three inequivalent S sites. In the first S site, S(1) is bonded to one Mg(1), one Mo(2), and two equivalent Mo(1) atoms to form distorted SMgMo3 trigonal pyramids that share corners with three equivalent S(3)MgFeMo2 trigonal pyramids, corners with three equivalent S(1)MgMo3 trigonal pyramids, corners with six equivalent S(2)MgFeMo2 trigonal pyramids,  an edgeedge with one S(3)MgFeMo2 trigonal pyramid, and edges with two equivalent S(2)MgFeMo2 trigonal pyramids. In the second S site, S(2) is bonded to one Mg(1), one Mo(1), one Mo(2), and one Fe(1) atom to form distorted SMgFeMo2 trigonal pyramids that share corners with three equivalent S(3)MgFeMo2 trigonal pyramids, corners with three equivalent S(1)MgMo3 trigonal pyramids, corners with six equivalent S(2)MgFeMo2 trigonal pyramids,  an edgeedge with one S(2)MgFeMo2 trigonal pyramid,  an edgeedge with one S(3)MgFeMo2 trigonal pyramid, and  an edgeedge with one S(1)MgMo3 trigonal pyramid. In the third S site, S(3) is bonded to one Mg(1), two equivalent Mo(1), and one Fe(1) atom to form distorted SMgFeMo2 trigonal pyramids that share corners with three equivalent S(3)MgFeMo2 trigonal pyramids, corners with three equivalent S(1)MgMo3 trigonal pyramids, corners with six equivalent S(2)MgFeMo2 trigonal pyramids,  an edgeedge with one S(1)MgMo3 trigonal pyramid, and edges with two equivalent S(2)MgFeMo2 trigonal pyramids.
Mg2Mo3FeS8 is Spinel-derived structured and crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to one S(1), one S(3), and two equivalent S(2) atoms to form MgS4 tetrahedra that share corners with three equivalent Mo(2)S6 octahedra, corners with three equivalent Fe(1)S6 octahedra, and corners with six equivalent Mo(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 57-60°. The Mg(1)-S(1) bond length is 2.43 Å. The Mg(1)-S(3) bond length is 2.45 Å. Both Mg(1)-S(2) bond lengths are 2.45 Å. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form MoS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Mo(1)S6 octahedra, edges with two equivalent Mo(2)S6 octahedra, and edges with two equivalent Fe(1)S6 octahedra. Both Mo(1)-S(1) bond lengths are 2.49 Å. Both Mo(1)-S(2) bond lengths are 2.49 Å. Both Mo(1)-S(3) bond lengths are 2.49 Å. In the second Mo site, Mo(2) is bonded to two equivalent S(1) and four equivalent S(2) atoms to form MoS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Fe(1)S6 octahedra, and edges with four equivalent Mo(1)S6 octahedra. Both Mo(2)-S(1) bond lengths are 2.49 Å. All Mo(2)-S(2) bond lengths are 2.49 Å. Fe(1) is bonded to two equivalent S(3) and four equivalent S(2) atoms to form FeS6 octahedra that share corners with six equivalent Mg(1)S4 tetrahedra, edges with two equivalent Mo(2)S6 octahedra, and edges with four equivalent Mo(1)S6 octahedra. Both Fe(1)-S(3) bond lengths are 2.44 Å. All Fe(1)-S(2) bond lengths are 2.45 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded to one Mg(1), one Mo(2), and two equivalent Mo(1) atoms to form distorted SMgMo3 trigonal pyramids that share corners with three equivalent S(3)MgFeMo2 trigonal pyramids, corners with three equivalent S(1)MgMo3 trigonal pyramids, corners with six equivalent S(2)MgFeMo2 trigonal pyramids,  an edgeedge with one S(3)MgFeMo2 trigonal pyramid, and edges with two equivalent S(2)MgFeMo2 trigonal pyramids. In the second S site, S(2) is bonded to one Mg(1), one Mo(1), one Mo(2), and one Fe(1) atom to form distorted SMgFeMo2 trigonal pyramids that share corners with three equivalent S(3)MgFeMo2 trigonal pyramids, corners with three equivalent S(1)MgMo3 trigonal pyramids, corners with six equivalent S(2)MgFeMo2 trigonal pyramids,  an edgeedge with one S(2)MgFeMo2 trigonal pyramid,  an edgeedge with one S(3)MgFeMo2 trigonal pyramid, and  an edgeedge with one S(1)MgMo3 trigonal pyramid. In the third S site, S(3) is bonded to one Mg(1), two equivalent Mo(1), and one Fe(1) atom to form distorted SMgFeMo2 trigonal pyramids that share corners with three equivalent S(3)MgFeMo2 trigonal pyramids, corners with three equivalent S(1)MgMo3 trigonal pyramids, corners with six equivalent S(2)MgFeMo2 trigonal pyramids,  an edgeedge with one S(1)MgMo3 trigonal pyramid, and edges with two equivalent S(2)MgFeMo2 trigonal pyramids.