CoAsS is Marcasite-derived structured and crystallizes in the monoclinic P2/m space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent As(1) and four equivalent S(1) atoms to form CoAs2S4 octahedra that share corners with eight equivalent Co(2)As4S2 octahedra, corners with two equivalent As(1)Co3As tetrahedra, and edges with two equivalent Co(1)As2S4 octahedra. The corner-sharing octahedral tilt angles range from 54-57°. In the second Co site, Co(2) is bonded to four equivalent As(1) and two equivalent S(1) atoms to form CoAs4S2 octahedra that share corners with eight equivalent Co(1)As2S4 octahedra, corners with four equivalent As(1)Co3As tetrahedra, and edges with two equivalent Co(2)As4S2 octahedra. The corner-sharing octahedral tilt angles range from 54-57°. As(1) is bonded to one Co(1), two equivalent Co(2), and one As(1) atom to form distorted AsCo3As tetrahedra that share  a cornercorner with one Co(1)As2S4 octahedra, corners with two equivalent Co(2)As4S2 octahedra, corners with five equivalent As(1)Co3As tetrahedra, and  an edgeedge with one As(1)Co3As tetrahedra. The corner-sharing octahedral tilt angles range from 74-81°. S(1) is bonded in a distorted trigonal planar geometry to one Co(2) and two equivalent Co(1) atoms.
CoAsS is Marcasite-derived structured and crystallizes in the monoclinic P2/m space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent As(1) and four equivalent S(1) atoms to form CoAs2S4 octahedra that share corners with eight equivalent Co(2)As4S2 octahedra, corners with two equivalent As(1)Co3As tetrahedra, and edges with two equivalent Co(1)As2S4 octahedra. The corner-sharing octahedral tilt angles range from 54-57°. Both Co(1)-As(1) bond lengths are 2.35 Å. All Co(1)-S(1) bond lengths are 2.25 Å. In the second Co site, Co(2) is bonded to four equivalent As(1) and two equivalent S(1) atoms to form CoAs4S2 octahedra that share corners with eight equivalent Co(1)As2S4 octahedra, corners with four equivalent As(1)Co3As tetrahedra, and edges with two equivalent Co(2)As4S2 octahedra. The corner-sharing octahedral tilt angles range from 54-57°. All Co(2)-As(1) bond lengths are 2.36 Å. Both Co(2)-S(1) bond lengths are 2.22 Å. As(1) is bonded to one Co(1), two equivalent Co(2), and one As(1) atom to form distorted AsCo3As tetrahedra that share  a cornercorner with one Co(1)As2S4 octahedra, corners with two equivalent Co(2)As4S2 octahedra, corners with five equivalent As(1)Co3As tetrahedra, and  an edgeedge with one As(1)Co3As tetrahedra. The corner-sharing octahedral tilt angles range from 74-81°. The As(1)-As(1) bond length is 2.42 Å. S(1) is bonded in a distorted trigonal planar geometry to one Co(2) and two equivalent Co(1) atoms.