Tb(CuSe)3 crystallizes in the trigonal R-3 space group. Tb(1) is bonded to six equivalent Se(1) atoms to form TbSe6 octahedra that share corners with twelve equivalent Cu(1)Se4 tetrahedra, edges with three equivalent Tb(1)Se6 octahedra, and edges with six equivalent Cu(1)Se4 tetrahedra. Cu(1) is bonded to four equivalent Se(1) atoms to form CuSe4 tetrahedra that share corners with four equivalent Tb(1)Se6 octahedra, corners with six equivalent Cu(1)Se4 tetrahedra, edges with two equivalent Tb(1)Se6 octahedra, and edges with three equivalent Cu(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 16-57°. Se(1) is bonded to two equivalent Tb(1) and four equivalent Cu(1) atoms to form a mixture of distorted corner and edge-sharing SeTb2Cu4 octahedra. The corner-sharing octahedral tilt angles range from 1-91°.
Tb(CuSe)3 crystallizes in the trigonal R-3 space group. Tb(1) is bonded to six equivalent Se(1) atoms to form TbSe6 octahedra that share corners with twelve equivalent Cu(1)Se4 tetrahedra, edges with three equivalent Tb(1)Se6 octahedra, and edges with six equivalent Cu(1)Se4 tetrahedra. All Tb(1)-Se(1) bond lengths are 2.87 Å. Cu(1) is bonded to four equivalent Se(1) atoms to form CuSe4 tetrahedra that share corners with four equivalent Tb(1)Se6 octahedra, corners with six equivalent Cu(1)Se4 tetrahedra, edges with two equivalent Tb(1)Se6 octahedra, and edges with three equivalent Cu(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 16-57°. There are a spread of Cu(1)-Se(1) bond distances ranging from 2.43-2.50 Å. Se(1) is bonded to two equivalent Tb(1) and four equivalent Cu(1) atoms to form a mixture of distorted corner and edge-sharing SeTb2Cu4 octahedra. The corner-sharing octahedral tilt angles range from 1-91°.