La4As2S5O4 crystallizes in the triclinic P1 space group. There are four inequivalent La sites. In the first La site, La(1) is bonded in a 4-coordinate geometry to one S(5), two equivalent S(3), two equivalent S(4), one O(3), one O(4), and two equivalent O(1) atoms. In the second La site, La(2) is bonded in a 4-coordinate geometry to two equivalent S(3), two equivalent S(4), one O(3), one O(4), and two equivalent O(2) atoms. In the third La site, La(3) is bonded in a 4-coordinate geometry to one S(5), two equivalent S(1), two equivalent S(2), one O(1), one O(2), and two equivalent O(3) atoms. In the fourth La site, La(4) is bonded in a 4-coordinate geometry to two equivalent S(1), two equivalent S(2), one O(1), one O(2), and two equivalent O(4) atoms. There are two inequivalent As sites. In the first As site, As(1) is bonded to one S(2), one S(3), and two equivalent S(5) atoms to form corner-sharing AsS4 tetrahedra. In the second As site, As(2) is bonded in a distorted T-shaped geometry to one S(1), one S(4), and one S(5) atom. There are five inequivalent S sites. In the first S site, S(1) is bonded in a 5-coordinate geometry to two equivalent La(3), two equivalent La(4), and one As(2) atom. In the second S site, S(2) is bonded in a 5-coordinate geometry to two equivalent La(3), two equivalent La(4), and one As(1) atom. In the third S site, S(3) is bonded in a 5-coordinate geometry to two equivalent La(1), two equivalent La(2), and one As(1) atom. In the fourth S site, S(4) is bonded in a 5-coordinate geometry to two equivalent La(1), two equivalent La(2), and one As(2) atom. In the fifth S site, S(5) is bonded to one La(1), one La(3), one As(2), and two equivalent As(1) atoms to form distorted SLa2As3 trigonal bipyramids that share  a cornercorner with one O(2)La4 tetrahedra,  a cornercorner with one O(4)La4 tetrahedra, corners with three equivalent O(1)La4 tetrahedra, corners with three equivalent O(3)La4 tetrahedra, and corners with two equivalent S(5)La2As3 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded to one La(3), one La(4), and two equivalent La(1) atoms to form OLa4 tetrahedra that share corners with two equivalent O(1)La4 tetrahedra, corners with two equivalent O(2)La4 tetrahedra, corners with three equivalent S(5)La2As3 trigonal bipyramids, edges with two equivalent O(3)La4 tetrahedra, and edges with two equivalent O(4)La4 tetrahedra. In the second O site, O(2) is bonded to one La(3), one La(4), and two equivalent La(2) atoms to form OLa4 tetrahedra that share corners with two equivalent O(1)La4 tetrahedra, corners with two equivalent O(2)La4 tetrahedra,  a cornercorner with one S(5)La2As3 trigonal bipyramid, edges with two equivalent O(3)La4 tetrahedra, and edges with two equivalent O(4)La4 tetrahedra. In the third O site, O(3) is bonded to one La(1), one La(2), and two equivalent La(3) atoms to form OLa4 tetrahedra that share corners with two equivalent O(3)La4 tetrahedra, corners with two equivalent O(4)La4 tetrahedra, corners with three equivalent S(5)La2As3 trigonal bipyramids, edges with two equivalent O(1)La4 tetrahedra, and edges with two equivalent O(2)La4 tetrahedra. In the fourth O site, O(4) is bonded to one La(1), one La(2), and two equivalent La(4) atoms to form OLa4 tetrahedra that share corners with two equivalent O(3)La4 tetrahedra, corners with two equivalent O(4)La4 tetrahedra,  a cornercorner with one S(5)La2As3 trigonal bipyramid, edges with two equivalent O(1)La4 tetrahedra, and edges with two equivalent O(2)La4 tetrahedra.
La4As2S5O4 crystallizes in the triclinic P1 space group. There are four inequivalent La sites. In the first La site, La(1) is bonded in a 4-coordinate geometry to one S(5), two equivalent S(3), two equivalent S(4), one O(3), one O(4), and two equivalent O(1) atoms. The La(1)-S(5) bond length is 3.44 Å. There is one shorter (3.26 Å) and one longer (3.59 Å) La(1)-S(3) bond length. There is one shorter (3.29 Å) and one longer (3.48 Å) La(1)-S(4) bond length. The La(1)-O(3) bond length is 2.39 Å. The La(1)-O(4) bond length is 2.40 Å. There is one shorter (2.40 Å) and one longer (2.45 Å) La(1)-O(1) bond length. In the second La site, La(2) is bonded in a 4-coordinate geometry to two equivalent S(3), two equivalent S(4), one O(3), one O(4), and two equivalent O(2) atoms. There is one shorter (3.12 Å) and one longer (3.26 Å) La(2)-S(3) bond length. There is one shorter (3.23 Å) and one longer (3.28 Å) La(2)-S(4) bond length. The La(2)-O(3) bond length is 2.42 Å. The La(2)-O(4) bond length is 2.39 Å. There is one shorter (2.42 Å) and one longer (2.43 Å) La(2)-O(2) bond length. In the third La site, La(3) is bonded in a 4-coordinate geometry to one S(5), two equivalent S(1), two equivalent S(2), one O(1), one O(2), and two equivalent O(3) atoms. The La(3)-S(5) bond length is 3.42 Å. There is one shorter (3.28 Å) and one longer (3.46 Å) La(3)-S(1) bond length. There is one shorter (3.26 Å) and one longer (3.62 Å) La(3)-S(2) bond length. The La(3)-O(1) bond length is 2.41 Å. The La(3)-O(2) bond length is 2.39 Å. There is one shorter (2.40 Å) and one longer (2.44 Å) La(3)-O(3) bond length. In the fourth La site, La(4) is bonded in a 4-coordinate geometry to two equivalent S(1), two equivalent S(2), one O(1), one O(2), and two equivalent O(4) atoms. There is one shorter (3.23 Å) and one longer (3.28 Å) La(4)-S(1) bond length. There is one shorter (3.12 Å) and one longer (3.27 Å) La(4)-S(2) bond length. The La(4)-O(1) bond length is 2.39 Å. The La(4)-O(2) bond length is 2.41 Å. There is one shorter (2.43 Å) and one longer (2.44 Å) La(4)-O(4) bond length. There are two inequivalent As sites. In the first As site, As(1) is bonded to one S(2), one S(3), and two equivalent S(5) atoms to form corner-sharing AsS4 tetrahedra. The As(1)-S(2) bond length is 2.27 Å. The As(1)-S(3) bond length is 2.28 Å. There is one shorter (2.39 Å) and one longer (2.72 Å) As(1)-S(5) bond length. In the second As site, As(2) is bonded in a distorted T-shaped geometry to one S(1), one S(4), and one S(5) atom. The As(2)-S(1) bond length is 2.29 Å. The As(2)-S(4) bond length is 2.28 Å. The As(2)-S(5) bond length is 2.33 Å. There are five inequivalent S sites. In the first S site, S(1) is bonded in a 5-coordinate geometry to two equivalent La(3), two equivalent La(4), and one As(2) atom. In the second S site, S(2) is bonded in a 5-coordinate geometry to two equivalent La(3), two equivalent La(4), and one As(1) atom. In the third S site, S(3) is bonded in a 5-coordinate geometry to two equivalent La(1), two equivalent La(2), and one As(1) atom. In the fourth S site, S(4) is bonded in a 5-coordinate geometry to two equivalent La(1), two equivalent La(2), and one As(2) atom. In the fifth S site, S(5) is bonded to one La(1), one La(3), one As(2), and two equivalent As(1) atoms to form distorted SLa2As3 trigonal bipyramids that share  a cornercorner with one O(2)La4 tetrahedra,  a cornercorner with one O(4)La4 tetrahedra, corners with three equivalent O(1)La4 tetrahedra, corners with three equivalent O(3)La4 tetrahedra, and corners with two equivalent S(5)La2As3 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded to one La(3), one La(4), and two equivalent La(1) atoms to form OLa4 tetrahedra that share corners with two equivalent O(1)La4 tetrahedra, corners with two equivalent O(2)La4 tetrahedra, corners with three equivalent S(5)La2As3 trigonal bipyramids, edges with two equivalent O(3)La4 tetrahedra, and edges with two equivalent O(4)La4 tetrahedra. In the second O site, O(2) is bonded to one La(3), one La(4), and two equivalent La(2) atoms to form OLa4 tetrahedra that share corners with two equivalent O(1)La4 tetrahedra, corners with two equivalent O(2)La4 tetrahedra,  a cornercorner with one S(5)La2As3 trigonal bipyramid, edges with two equivalent O(3)La4 tetrahedra, and edges with two equivalent O(4)La4 tetrahedra. In the third O site, O(3) is bonded to one La(1), one La(2), and two equivalent La(3) atoms to form OLa4 tetrahedra that share corners with two equivalent O(3)La4 tetrahedra, corners with two equivalent O(4)La4 tetrahedra, corners with three equivalent S(5)La2As3 trigonal bipyramids, edges with two equivalent O(1)La4 tetrahedra, and edges with two equivalent O(2)La4 tetrahedra. In the fourth O site, O(4) is bonded to one La(1), one La(2), and two equivalent La(4) atoms to form OLa4 tetrahedra that share corners with two equivalent O(3)La4 tetrahedra, corners with two equivalent O(4)La4 tetrahedra,  a cornercorner with one S(5)La2As3 trigonal bipyramid, edges with two equivalent O(1)La4 tetrahedra, and edges with two equivalent O(2)La4 tetrahedra.