Zn2Al2S5 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to one S(4), one S(5), and two equivalent S(1) atoms to form ZnS4 tetrahedra that share  a cornercorner with one Al(1)S4 tetrahedra, corners with two equivalent Zn(1)S4 tetrahedra, corners with three equivalent Zn(2)S4 tetrahedra, and corners with four equivalent Al(2)S4 tetrahedra. In the second Zn site, Zn(2) is bonded to one S(1), one S(2), one S(3), and one S(4) atom to form ZnS4 tetrahedra that share corners with two equivalent Al(2)S4 tetrahedra, corners with three equivalent Zn(1)S4 tetrahedra, and corners with four equivalent Al(1)S4 tetrahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one S(2), one S(4), and two equivalent S(3) atoms to form AlS4 tetrahedra that share  a cornercorner with one Zn(1)S4 tetrahedra,  a cornercorner with one Al(2)S4 tetrahedra, corners with two equivalent Al(1)S4 tetrahedra, and corners with four equivalent Zn(2)S4 tetrahedra. In the second Al site, Al(2) is bonded to one S(1), one S(2), and two equivalent S(5) atoms to form AlS4 tetrahedra that share  a cornercorner with one Al(1)S4 tetrahedra, corners with two equivalent Zn(2)S4 tetrahedra, corners with two equivalent Al(2)S4 tetrahedra, and corners with four equivalent Zn(1)S4 tetrahedra. There are five inequivalent S sites. In the first S site, S(1) is bonded to one Zn(2), two equivalent Zn(1), and one Al(2) atom to form corner-sharing SAlZn3 tetrahedra. In the second S site, S(2) is bonded in a trigonal non-coplanar geometry to one Zn(2), one Al(1), and one Al(2) atom. In the third S site, S(3) is bonded in a trigonal non-coplanar geometry to one Zn(2) and two equivalent Al(1) atoms. In the fourth S site, S(4) is bonded in a trigonal non-coplanar geometry to one Zn(1), one Zn(2), and one Al(1) atom. In the fifth S site, S(5) is bonded in a trigonal non-coplanar geometry to one Zn(1) and two equivalent Al(2) atoms.
Zn2Al2S5 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded to one S(4), one S(5), and two equivalent S(1) atoms to form ZnS4 tetrahedra that share  a cornercorner with one Al(1)S4 tetrahedra, corners with two equivalent Zn(1)S4 tetrahedra, corners with three equivalent Zn(2)S4 tetrahedra, and corners with four equivalent Al(2)S4 tetrahedra. The Zn(1)-S(4) bond length is 2.28 Å. The Zn(1)-S(5) bond length is 2.34 Å. There is one shorter (2.37 Å) and one longer (2.38 Å) Zn(1)-S(1) bond length. In the second Zn site, Zn(2) is bonded to one S(1), one S(2), one S(3), and one S(4) atom to form ZnS4 tetrahedra that share corners with two equivalent Al(2)S4 tetrahedra, corners with three equivalent Zn(1)S4 tetrahedra, and corners with four equivalent Al(1)S4 tetrahedra. The Zn(2)-S(1) bond length is 2.40 Å. The Zn(2)-S(2) bond length is 2.35 Å. The Zn(2)-S(3) bond length is 2.32 Å. The Zn(2)-S(4) bond length is 2.30 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one S(2), one S(4), and two equivalent S(3) atoms to form AlS4 tetrahedra that share  a cornercorner with one Zn(1)S4 tetrahedra,  a cornercorner with one Al(2)S4 tetrahedra, corners with two equivalent Al(1)S4 tetrahedra, and corners with four equivalent Zn(2)S4 tetrahedra. The Al(1)-S(2) bond length is 2.28 Å. The Al(1)-S(4) bond length is 2.23 Å. There is one shorter (2.25 Å) and one longer (2.27 Å) Al(1)-S(3) bond length. In the second Al site, Al(2) is bonded to one S(1), one S(2), and two equivalent S(5) atoms to form AlS4 tetrahedra that share  a cornercorner with one Al(1)S4 tetrahedra, corners with two equivalent Zn(2)S4 tetrahedra, corners with two equivalent Al(2)S4 tetrahedra, and corners with four equivalent Zn(1)S4 tetrahedra. The Al(2)-S(1) bond length is 2.28 Å. The Al(2)-S(2) bond length is 2.25 Å. There is one shorter (2.25 Å) and one longer (2.27 Å) Al(2)-S(5) bond length. There are five inequivalent S sites. In the first S site, S(1) is bonded to one Zn(2), two equivalent Zn(1), and one Al(2) atom to form corner-sharing SAlZn3 tetrahedra. In the second S site, S(2) is bonded in a trigonal non-coplanar geometry to one Zn(2), one Al(1), and one Al(2) atom. In the third S site, S(3) is bonded in a trigonal non-coplanar geometry to one Zn(2) and two equivalent Al(1) atoms. In the fourth S site, S(4) is bonded in a trigonal non-coplanar geometry to one Zn(1), one Zn(2), and one Al(1) atom. In the fifth S site, S(5) is bonded in a trigonal non-coplanar geometry to one Zn(1) and two equivalent Al(2) atoms.