Ba2Ga2S5 crystallizes in the monoclinic C2/c space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one S(1), one S(2), two equivalent S(3), two equivalent S(4), and two equivalent S(5) atoms. In the second Ba site, Ba(2) is bonded in a 7-coordinate geometry to one S(2), one S(5), one S(6), two equivalent S(3), and two equivalent S(4) atoms. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one S(2), one S(3), one S(5), and one S(6) atom to form corner-sharing GaS4 tetrahedra. In the second Ga site, Ga(2) is bonded to one S(1), one S(2), one S(4), and one S(5) atom to form corner-sharing GaS4 tetrahedra. There are six inequivalent S sites. In the first S site, S(1) is bonded in a distorted square co-planar geometry to two equivalent Ba(1) and two equivalent Ga(2) atoms. In the second S site, S(2) is bonded in a distorted see-saw-like geometry to one Ba(1), one Ba(2), one Ga(1), and one Ga(2) atom. In the third S site, S(3) is bonded in a 5-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), and one Ga(1) atom. In the fourth S site, S(4) is bonded to two equivalent Ba(1), two equivalent Ba(2), and one Ga(2) atom to form distorted SBa4Ga trigonal bipyramids that share corners with five equivalent S(5)Ba3Ga2 trigonal bipyramids,  an edgeedge with one S(5)Ba3Ga2 trigonal bipyramid, and edges with two equivalent S(4)Ba4Ga trigonal bipyramids. In the fifth S site, S(5) is bonded to one Ba(2), two equivalent Ba(1), one Ga(1), and one Ga(2) atom to form distorted SBa3Ga2 trigonal bipyramids that share corners with five equivalent S(4)Ba4Ga trigonal bipyramids,  an edgeedge with one S(5)Ba3Ga2 trigonal bipyramid, and  an edgeedge with one S(4)Ba4Ga trigonal bipyramid. In the sixth S site, S(6) is bonded in a 4-coordinate geometry to two equivalent Ba(2) and two equivalent Ga(1) atoms.
Ba2Ga2S5 crystallizes in the monoclinic C2/c space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one S(1), one S(2), two equivalent S(3), two equivalent S(4), and two equivalent S(5) atoms. The Ba(1)-S(1) bond length is 3.36 Å. The Ba(1)-S(2) bond length is 3.40 Å. There is one shorter (3.21 Å) and one longer (3.70 Å) Ba(1)-S(3) bond length. There is one shorter (3.16 Å) and one longer (3.25 Å) Ba(1)-S(4) bond length. There is one shorter (3.21 Å) and one longer (3.35 Å) Ba(1)-S(5) bond length. In the second Ba site, Ba(2) is bonded in a 7-coordinate geometry to one S(2), one S(5), one S(6), two equivalent S(3), and two equivalent S(4) atoms. The Ba(2)-S(2) bond length is 3.27 Å. The Ba(2)-S(5) bond length is 3.38 Å. The Ba(2)-S(6) bond length is 3.33 Å. There is one shorter (3.16 Å) and one longer (3.24 Å) Ba(2)-S(3) bond length. There is one shorter (3.19 Å) and one longer (3.44 Å) Ba(2)-S(4) bond length. There are two inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one S(2), one S(3), one S(5), and one S(6) atom to form corner-sharing GaS4 tetrahedra. The Ga(1)-S(2) bond length is 2.26 Å. The Ga(1)-S(3) bond length is 2.21 Å. The Ga(1)-S(5) bond length is 2.30 Å. The Ga(1)-S(6) bond length is 2.30 Å. In the second Ga site, Ga(2) is bonded to one S(1), one S(2), one S(4), and one S(5) atom to form corner-sharing GaS4 tetrahedra. The Ga(2)-S(1) bond length is 2.29 Å. The Ga(2)-S(2) bond length is 2.30 Å. The Ga(2)-S(4) bond length is 2.25 Å. The Ga(2)-S(5) bond length is 2.29 Å. There are six inequivalent S sites. In the first S site, S(1) is bonded in a distorted square co-planar geometry to two equivalent Ba(1) and two equivalent Ga(2) atoms. In the second S site, S(2) is bonded in a distorted see-saw-like geometry to one Ba(1), one Ba(2), one Ga(1), and one Ga(2) atom. In the third S site, S(3) is bonded in a 5-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), and one Ga(1) atom. In the fourth S site, S(4) is bonded to two equivalent Ba(1), two equivalent Ba(2), and one Ga(2) atom to form distorted SBa4Ga trigonal bipyramids that share corners with five equivalent S(5)Ba3Ga2 trigonal bipyramids,  an edgeedge with one S(5)Ba3Ga2 trigonal bipyramid, and edges with two equivalent S(4)Ba4Ga trigonal bipyramids. In the fifth S site, S(5) is bonded to one Ba(2), two equivalent Ba(1), one Ga(1), and one Ga(2) atom to form distorted SBa3Ga2 trigonal bipyramids that share corners with five equivalent S(4)Ba4Ga trigonal bipyramids,  an edgeedge with one S(5)Ba3Ga2 trigonal bipyramid, and  an edgeedge with one S(4)Ba4Ga trigonal bipyramid. In the sixth S site, S(6) is bonded in a 4-coordinate geometry to two equivalent Ba(2) and two equivalent Ga(1) atoms.