KY2CuS4 crystallizes in the orthorhombic Cmcm space group. K(1) is bonded in a 6-coordinate geometry to two equivalent S(3) and four equivalent S(2) atoms. Y(1) is bonded to one S(3), two equivalent S(1), and three equivalent S(2) atoms to form YS6 octahedra that share corners with three equivalent Y(1)S6 octahedra,  a cornercorner with one Cu(1)S4 tetrahedra, edges with five equivalent Y(1)S6 octahedra, and edges with two equivalent Cu(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 0-38°. Cu(1) is bonded to two equivalent S(2) and two equivalent S(3) atoms to form CuS4 tetrahedra that share corners with two equivalent Y(1)S6 octahedra, corners with two equivalent Cu(1)S4 tetrahedra, and edges with four equivalent Y(1)S6 octahedra. The corner-sharing octahedral tilt angles are 5°. There are three inequivalent S sites. In the first S site, S(1) is bonded in a distorted square co-planar geometry to four equivalent Y(1) atoms. In the second S site, S(2) is bonded to two equivalent K(1), three equivalent Y(1), and one Cu(1) atom to form a mixture of distorted edge, corner, and face-sharing SK2Y3Cu octahedra. The corner-sharing octahedral tilt angles are 64°. In the third S site, S(3) is bonded in a 6-coordinate geometry to two equivalent K(1), two equivalent Y(1), and two equivalent Cu(1) atoms.
KY2CuS4 crystallizes in the orthorhombic Cmcm space group. K(1) is bonded in a 6-coordinate geometry to two equivalent S(3) and four equivalent S(2) atoms. Both K(1)-S(3) bond lengths are 3.12 Å. All K(1)-S(2) bond lengths are 3.25 Å. Y(1) is bonded to one S(3), two equivalent S(1), and three equivalent S(2) atoms to form YS6 octahedra that share corners with three equivalent Y(1)S6 octahedra,  a cornercorner with one Cu(1)S4 tetrahedra, edges with five equivalent Y(1)S6 octahedra, and edges with two equivalent Cu(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 0-38°. The Y(1)-S(3) bond length is 2.72 Å. Both Y(1)-S(1) bond lengths are 2.83 Å. There are two shorter (2.72 Å) and one longer (2.77 Å) Y(1)-S(2) bond length. Cu(1) is bonded to two equivalent S(2) and two equivalent S(3) atoms to form CuS4 tetrahedra that share corners with two equivalent Y(1)S6 octahedra, corners with two equivalent Cu(1)S4 tetrahedra, and edges with four equivalent Y(1)S6 octahedra. The corner-sharing octahedral tilt angles are 5°. Both Cu(1)-S(2) bond lengths are 2.34 Å. Both Cu(1)-S(3) bond lengths are 2.35 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded in a distorted square co-planar geometry to four equivalent Y(1) atoms. In the second S site, S(2) is bonded to two equivalent K(1), three equivalent Y(1), and one Cu(1) atom to form a mixture of distorted edge, corner, and face-sharing SK2Y3Cu octahedra. The corner-sharing octahedral tilt angles are 64°. In the third S site, S(3) is bonded in a 6-coordinate geometry to two equivalent K(1), two equivalent Y(1), and two equivalent Cu(1) atoms.