Mg2W3FeS8 crystallizes in the trigonal R3m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one S(1) and three equivalent S(3) atoms to form MgS4 trigonal pyramids that share corners with nine equivalent W(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 46-68°. In the second Mg site, Mg(2) is bonded in a rectangular see-saw-like geometry to one S(4) and three equivalent S(2) atoms. W(1) is bonded to one S(1), one S(4), two equivalent S(2), and two equivalent S(3) atoms to form distorted WS6 octahedra that share corners with three equivalent Mg(1)S4 trigonal pyramids and edges with four equivalent W(1)S6 octahedra. Fe(1) is bonded in a 6-coordinate geometry to three equivalent S(2) and three equivalent S(3) atoms. There are four inequivalent S sites. In the first S site, S(1) is bonded in a 4-coordinate geometry to one Mg(1) and three equivalent W(1) atoms. In the second S site, S(2) is bonded in a 4-coordinate geometry to one Mg(2), two equivalent W(1), and one Fe(1) atom. In the third S site, S(3) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent W(1), and one Fe(1) atom. In the fourth S site, S(4) is bonded in a distorted single-bond geometry to one Mg(2) and three equivalent W(1) atoms.
Mg2W3FeS8 crystallizes in the trigonal R3m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one S(1) and three equivalent S(3) atoms to form MgS4 trigonal pyramids that share corners with nine equivalent W(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 46-68°. The Mg(1)-S(1) bond length is 2.60 Å. All Mg(1)-S(3) bond lengths are 2.34 Å. In the second Mg site, Mg(2) is bonded in a rectangular see-saw-like geometry to one S(4) and three equivalent S(2) atoms. The Mg(2)-S(4) bond length is 2.38 Å. All Mg(2)-S(2) bond lengths are 2.43 Å. W(1) is bonded to one S(1), one S(4), two equivalent S(2), and two equivalent S(3) atoms to form distorted WS6 octahedra that share corners with three equivalent Mg(1)S4 trigonal pyramids and edges with four equivalent W(1)S6 octahedra. The W(1)-S(1) bond length is 2.38 Å. The W(1)-S(4) bond length is 2.61 Å. Both W(1)-S(2) bond lengths are 2.50 Å. Both W(1)-S(3) bond lengths are 2.42 Å. Fe(1) is bonded in a 6-coordinate geometry to three equivalent S(2) and three equivalent S(3) atoms. All Fe(1)-S(2) bond lengths are 2.29 Å. All Fe(1)-S(3) bond lengths are 2.78 Å. There are four inequivalent S sites. In the first S site, S(1) is bonded in a 4-coordinate geometry to one Mg(1) and three equivalent W(1) atoms. In the second S site, S(2) is bonded in a 4-coordinate geometry to one Mg(2), two equivalent W(1), and one Fe(1) atom. In the third S site, S(3) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent W(1), and one Fe(1) atom. In the fourth S site, S(4) is bonded in a distorted single-bond geometry to one Mg(2) and three equivalent W(1) atoms.