Fe2AsS3 is pyrite-derived structured and crystallizes in the monoclinic Pm space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one As(1), one S(1), two equivalent S(2), and two equivalent S(3) atoms to form FeAsS5 octahedra that share corners with eight equivalent Fe(2)As2S4 octahedra,  a cornercorner with one As(1)Fe3S tetrahedra,  a cornercorner with one S(1)Fe3As tetrahedra, and edges with two equivalent Fe(1)AsS5 octahedra. The corner-sharing octahedral tilt angles range from 54-58°. In the second Fe site, Fe(2) is bonded to two equivalent As(1), one S(2), one S(3), and two equivalent S(1) atoms to form FeAs2S4 octahedra that share corners with eight equivalent Fe(1)AsS5 octahedra, corners with two equivalent As(1)Fe3S tetrahedra, corners with two equivalent S(1)Fe3As tetrahedra, and edges with two equivalent Fe(2)As2S4 octahedra. The corner-sharing octahedral tilt angles range from 54-58°. As(1) is bonded to one Fe(1), two equivalent Fe(2), and one S(1) atom to form AsFe3S tetrahedra that share  a cornercorner with one Fe(1)AsS5 octahedra, corners with two equivalent Fe(2)As2S4 octahedra, corners with two equivalent As(1)Fe3S tetrahedra, corners with three equivalent S(1)Fe3As tetrahedra, and  an edgeedge with one S(1)Fe3As tetrahedra. The corner-sharing octahedral tilt angles range from 74-76°. There are three inequivalent S sites. In the first S site, S(1) is bonded to one Fe(1), two equivalent Fe(2), and one As(1) atom to form SFe3As tetrahedra that share  a cornercorner with one Fe(1)AsS5 octahedra, corners with two equivalent Fe(2)As2S4 octahedra, corners with two equivalent S(1)Fe3As tetrahedra, corners with three equivalent As(1)Fe3S tetrahedra, and  an edgeedge with one As(1)Fe3S tetrahedra. The corner-sharing octahedral tilt angles range from 74-77°. In the second S site, S(2) is bonded in a 3-coordinate geometry to one Fe(2) and two equivalent Fe(1) atoms. In the third S site, S(3) is bonded in a 3-coordinate geometry to one Fe(2) and two equivalent Fe(1) atoms.
Fe2AsS3 is pyrite-derived structured and crystallizes in the monoclinic Pm space group. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one As(1), one S(1), two equivalent S(2), and two equivalent S(3) atoms to form FeAsS5 octahedra that share corners with eight equivalent Fe(2)As2S4 octahedra,  a cornercorner with one As(1)Fe3S tetrahedra,  a cornercorner with one S(1)Fe3As tetrahedra, and edges with two equivalent Fe(1)AsS5 octahedra. The corner-sharing octahedral tilt angles range from 54-58°. The Fe(1)-As(1) bond length is 2.32 Å. The Fe(1)-S(1) bond length is 2.22 Å. Both Fe(1)-S(2) bond lengths are 2.24 Å. Both Fe(1)-S(3) bond lengths are 2.25 Å. In the second Fe site, Fe(2) is bonded to two equivalent As(1), one S(2), one S(3), and two equivalent S(1) atoms to form FeAs2S4 octahedra that share corners with eight equivalent Fe(1)AsS5 octahedra, corners with two equivalent As(1)Fe3S tetrahedra, corners with two equivalent S(1)Fe3As tetrahedra, and edges with two equivalent Fe(2)As2S4 octahedra. The corner-sharing octahedral tilt angles range from 54-58°. Both Fe(2)-As(1) bond lengths are 2.38 Å. The Fe(2)-S(2) bond length is 2.25 Å. The Fe(2)-S(3) bond length is 2.23 Å. Both Fe(2)-S(1) bond lengths are 2.28 Å. As(1) is bonded to one Fe(1), two equivalent Fe(2), and one S(1) atom to form AsFe3S tetrahedra that share  a cornercorner with one Fe(1)AsS5 octahedra, corners with two equivalent Fe(2)As2S4 octahedra, corners with two equivalent As(1)Fe3S tetrahedra, corners with three equivalent S(1)Fe3As tetrahedra, and  an edgeedge with one S(1)Fe3As tetrahedra. The corner-sharing octahedral tilt angles range from 74-76°. The As(1)-S(1) bond length is 2.31 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded to one Fe(1), two equivalent Fe(2), and one As(1) atom to form SFe3As tetrahedra that share  a cornercorner with one Fe(1)AsS5 octahedra, corners with two equivalent Fe(2)As2S4 octahedra, corners with two equivalent S(1)Fe3As tetrahedra, corners with three equivalent As(1)Fe3S tetrahedra, and  an edgeedge with one As(1)Fe3S tetrahedra. The corner-sharing octahedral tilt angles range from 74-77°. In the second S site, S(2) is bonded in a 3-coordinate geometry to one Fe(2) and two equivalent Fe(1) atoms. In the third S site, S(3) is bonded in a 3-coordinate geometry to one Fe(2) and two equivalent Fe(1) atoms.