Cr3NiCu2Se8 is Spinel-derived structured and crystallizes in the trigonal R-3m space group. Cr(1) is bonded to two equivalent Se(1) and four equivalent Se(2) atoms to form CrSe6 octahedra that share corners with six equivalent Cu(1)Se4 tetrahedra, edges with two equivalent Ni(1)Se6 octahedra, and edges with four equivalent Cr(1)Se6 octahedra. Ni(1) is bonded to six equivalent Se(2) atoms to form NiSe6 octahedra that share corners with six equivalent Cu(1)Se4 tetrahedra and edges with six equivalent Cr(1)Se6 octahedra. Cu(1) is bonded to one Se(1) and three equivalent Se(2) atoms to form CuSe4 tetrahedra that share corners with three equivalent Ni(1)Se6 octahedra and corners with nine equivalent Cr(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 57-58°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Cr(1) and one Cu(1) atom. In the second Se site, Se(2) is bonded to two equivalent Cr(1), one Ni(1), and one Cu(1) atom to form a mixture of distorted edge and corner-sharing SeCr2CuNi trigonal pyramids.
Cr3NiCu2Se8 is Spinel-derived structured and crystallizes in the trigonal R-3m space group. Cr(1) is bonded to two equivalent Se(1) and four equivalent Se(2) atoms to form CrSe6 octahedra that share corners with six equivalent Cu(1)Se4 tetrahedra, edges with two equivalent Ni(1)Se6 octahedra, and edges with four equivalent Cr(1)Se6 octahedra. Both Cr(1)-Se(1) bond lengths are 2.50 Å. All Cr(1)-Se(2) bond lengths are 2.50 Å. Ni(1) is bonded to six equivalent Se(2) atoms to form NiSe6 octahedra that share corners with six equivalent Cu(1)Se4 tetrahedra and edges with six equivalent Cr(1)Se6 octahedra. All Ni(1)-Se(2) bond lengths are 2.49 Å. Cu(1) is bonded to one Se(1) and three equivalent Se(2) atoms to form CuSe4 tetrahedra that share corners with three equivalent Ni(1)Se6 octahedra and corners with nine equivalent Cr(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 57-58°. The Cu(1)-Se(1) bond length is 2.39 Å. All Cu(1)-Se(2) bond lengths are 2.38 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Cr(1) and one Cu(1) atom. In the second Se site, Se(2) is bonded to two equivalent Cr(1), one Ni(1), and one Cu(1) atom to form a mixture of distorted edge and corner-sharing SeCr2CuNi trigonal pyramids.