Mg2W3GaS8 crystallizes in the monoclinic Cm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one S(1), one S(4), and two equivalent S(5) atoms to form MgS4 tetrahedra that share corners with three equivalent W(2)S6 octahedra and corners with three equivalent Ga(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 45-62°. In the second Mg site, Mg(2) is bonded to one S(3), one S(6), and two equivalent S(2) atoms to form distorted MgS4 trigonal pyramids that share corners with three equivalent W(2)S6 octahedra and corners with three equivalent Ga(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 59-69°. There are two inequivalent W sites. In the first W site, W(1) is bonded in a 6-coordinate geometry to one S(1), one S(2), one S(3), one S(4), one S(5), and one S(6) atom. In the second W site, W(2) is bonded to one S(1), one S(6), two equivalent S(2), and two equivalent S(5) atoms to form distorted WS6 octahedra that share corners with three equivalent Mg(1)S4 tetrahedra, corners with three equivalent Mg(2)S4 trigonal pyramids, and edges with two equivalent Ga(1)S6 octahedra. Ga(1) is bonded to one S(3), one S(4), two equivalent S(2), and two equivalent S(5) atoms to form GaS6 octahedra that share corners with three equivalent Mg(1)S4 tetrahedra, corners with three equivalent Mg(2)S4 trigonal pyramids, and edges with two equivalent W(2)S6 octahedra. There are six inequivalent S sites. In the first S site, S(1) is bonded in a 4-coordinate geometry to one Mg(1), one W(2), and two equivalent W(1) atoms. In the second S site, S(2) is bonded to one Mg(2), one W(1), one W(2), and one Ga(1) atom to form distorted SMgGaW2 trigonal pyramids that share  a cornercorner with one S(6)MgW3 tetrahedra, corners with five equivalent S(5)MgGaW2 tetrahedra,  a cornercorner with one S(2)MgGaW2 trigonal pyramid,  a cornercorner with one S(3)MgGaW2 trigonal pyramid,  an edgeedge with one S(6)MgW3 tetrahedra,  an edgeedge with one S(2)MgGaW2 trigonal pyramid, and  an edgeedge with one S(3)MgGaW2 trigonal pyramid. In the third S site, S(3) is bonded to one Mg(2), two equivalent W(1), and one Ga(1) atom to form distorted SMgGaW2 trigonal pyramids that share  a cornercorner with one S(6)MgW3 tetrahedra, corners with four equivalent S(5)MgGaW2 tetrahedra, corners with two equivalent S(2)MgGaW2 trigonal pyramids,  an edgeedge with one S(6)MgW3 tetrahedra, and edges with two equivalent S(2)MgGaW2 trigonal pyramids. In the fourth S site, S(4) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent W(1), and one Ga(1) atom. In the fifth S site, S(5) is bonded to one Mg(1), one W(1), one W(2), and one Ga(1) atom to form distorted SMgGaW2 tetrahedra that share  a cornercorner with one S(5)MgGaW2 tetrahedra, corners with two equivalent S(6)MgW3 tetrahedra, corners with two equivalent S(3)MgGaW2 trigonal pyramids, corners with five equivalent S(2)MgGaW2 trigonal pyramids, and  an edgeedge with one S(5)MgGaW2 tetrahedra. In the sixth S site, S(6) is bonded to one Mg(2), one W(2), and two equivalent W(1) atoms to form a mixture of distorted edge and corner-sharing SMgW3 tetrahedra.
Mg2W3GaS8 crystallizes in the monoclinic Cm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one S(1), one S(4), and two equivalent S(5) atoms to form MgS4 tetrahedra that share corners with three equivalent W(2)S6 octahedra and corners with three equivalent Ga(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 45-62°. The Mg(1)-S(1) bond length is 2.45 Å. The Mg(1)-S(4) bond length is 2.35 Å. Both Mg(1)-S(5) bond lengths are 2.35 Å. In the second Mg site, Mg(2) is bonded to one S(3), one S(6), and two equivalent S(2) atoms to form distorted MgS4 trigonal pyramids that share corners with three equivalent W(2)S6 octahedra and corners with three equivalent Ga(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 59-69°. The Mg(2)-S(3) bond length is 2.48 Å. The Mg(2)-S(6) bond length is 2.53 Å. Both Mg(2)-S(2) bond lengths are 2.47 Å. There are two inequivalent W sites. In the first W site, W(1) is bonded in a 6-coordinate geometry to one S(1), one S(2), one S(3), one S(4), one S(5), and one S(6) atom. The W(1)-S(1) bond length is 2.37 Å. The W(1)-S(2) bond length is 2.56 Å. The W(1)-S(3) bond length is 2.58 Å. The W(1)-S(4) bond length is 2.38 Å. The W(1)-S(5) bond length is 2.36 Å. The W(1)-S(6) bond length is 2.68 Å. In the second W site, W(2) is bonded to one S(1), one S(6), two equivalent S(2), and two equivalent S(5) atoms to form distorted WS6 octahedra that share corners with three equivalent Mg(1)S4 tetrahedra, corners with three equivalent Mg(2)S4 trigonal pyramids, and edges with two equivalent Ga(1)S6 octahedra. The W(2)-S(1) bond length is 2.38 Å. The W(2)-S(6) bond length is 2.66 Å. Both W(2)-S(2) bond lengths are 2.56 Å. Both W(2)-S(5) bond lengths are 2.38 Å. Ga(1) is bonded to one S(3), one S(4), two equivalent S(2), and two equivalent S(5) atoms to form GaS6 octahedra that share corners with three equivalent Mg(1)S4 tetrahedra, corners with three equivalent Mg(2)S4 trigonal pyramids, and edges with two equivalent W(2)S6 octahedra. The Ga(1)-S(3) bond length is 2.46 Å. The Ga(1)-S(4) bond length is 2.58 Å. Both Ga(1)-S(2) bond lengths are 2.45 Å. Both Ga(1)-S(5) bond lengths are 2.60 Å. There are six inequivalent S sites. In the first S site, S(1) is bonded in a 4-coordinate geometry to one Mg(1), one W(2), and two equivalent W(1) atoms. In the second S site, S(2) is bonded to one Mg(2), one W(1), one W(2), and one Ga(1) atom to form distorted SMgGaW2 trigonal pyramids that share  a cornercorner with one S(6)MgW3 tetrahedra, corners with five equivalent S(5)MgGaW2 tetrahedra,  a cornercorner with one S(2)MgGaW2 trigonal pyramid,  a cornercorner with one S(3)MgGaW2 trigonal pyramid,  an edgeedge with one S(6)MgW3 tetrahedra,  an edgeedge with one S(2)MgGaW2 trigonal pyramid, and  an edgeedge with one S(3)MgGaW2 trigonal pyramid. In the third S site, S(3) is bonded to one Mg(2), two equivalent W(1), and one Ga(1) atom to form distorted SMgGaW2 trigonal pyramids that share  a cornercorner with one S(6)MgW3 tetrahedra, corners with four equivalent S(5)MgGaW2 tetrahedra, corners with two equivalent S(2)MgGaW2 trigonal pyramids,  an edgeedge with one S(6)MgW3 tetrahedra, and edges with two equivalent S(2)MgGaW2 trigonal pyramids. In the fourth S site, S(4) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent W(1), and one Ga(1) atom. In the fifth S site, S(5) is bonded to one Mg(1), one W(1), one W(2), and one Ga(1) atom to form distorted SMgGaW2 tetrahedra that share  a cornercorner with one S(5)MgGaW2 tetrahedra, corners with two equivalent S(6)MgW3 tetrahedra, corners with two equivalent S(3)MgGaW2 trigonal pyramids, corners with five equivalent S(2)MgGaW2 trigonal pyramids, and  an edgeedge with one S(5)MgGaW2 tetrahedra. In the sixth S site, S(6) is bonded to one Mg(2), one W(2), and two equivalent W(1) atoms to form a mixture of distorted edge and corner-sharing SMgW3 tetrahedra.