YCuS2 crystallizes in the orthorhombic P2_12_12_1 space group. Y(1) is bonded to three equivalent S(1) and three equivalent S(2) atoms to form YS6 octahedra that share corners with four equivalent Y(1)S6 octahedra, corners with six equivalent Cu(1)S4 tetrahedra, edges with four equivalent Y(1)S6 octahedra, and edges with three equivalent Cu(1)S4 tetrahedra. The corner-sharing octahedral tilt angles are 52°. Cu(1) is bonded to one S(1) and three equivalent S(2) atoms to form CuS4 tetrahedra that share corners with six equivalent Y(1)S6 octahedra, corners with two equivalent Cu(1)S4 tetrahedra, edges with three equivalent Y(1)S6 octahedra, and edges with two equivalent Cu(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 14-58°. There are two inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to three equivalent Y(1) and one Cu(1) atom. In the second S site, S(2) is bonded to three equivalent Y(1) and three equivalent Cu(1) atoms to form distorted edge-sharing SY3Cu3 octahedra.
YCuS2 crystallizes in the orthorhombic P2_12_12_1 space group. Y(1) is bonded to three equivalent S(1) and three equivalent S(2) atoms to form YS6 octahedra that share corners with four equivalent Y(1)S6 octahedra, corners with six equivalent Cu(1)S4 tetrahedra, edges with four equivalent Y(1)S6 octahedra, and edges with three equivalent Cu(1)S4 tetrahedra. The corner-sharing octahedral tilt angles are 52°. There are two shorter (2.66 Å) and one longer (2.71 Å) Y(1)-S(1) bond length. There are two shorter (2.80 Å) and one longer (2.81 Å) Y(1)-S(2) bond length. Cu(1) is bonded to one S(1) and three equivalent S(2) atoms to form CuS4 tetrahedra that share corners with six equivalent Y(1)S6 octahedra, corners with two equivalent Cu(1)S4 tetrahedra, edges with three equivalent Y(1)S6 octahedra, and edges with two equivalent Cu(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 14-58°. The Cu(1)-S(1) bond length is 2.30 Å. There are a spread of Cu(1)-S(2) bond distances ranging from 2.36-2.40 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded in a rectangular see-saw-like geometry to three equivalent Y(1) and one Cu(1) atom. In the second S site, S(2) is bonded to three equivalent Y(1) and three equivalent Cu(1) atoms to form distorted edge-sharing SY3Cu3 octahedra.