CoNiSe2 crystallizes in the trigonal P-3m1 space group. Co(1) is bonded to six equivalent Se(1) atoms to form distorted CoSe6 octahedra that share corners with twelve equivalent Ni(1)Se6 octahedra, edges with six equivalent Co(1)Se6 octahedra, and faces with two equivalent Ni(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 51°. Ni(1) is bonded to six equivalent Se(1) atoms to form distorted NiSe6 octahedra that share corners with twelve equivalent Co(1)Se6 octahedra, edges with six equivalent Ni(1)Se6 octahedra, and faces with two equivalent Co(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 51°. Se(1) is bonded in a 6-coordinate geometry to three equivalent Co(1) and three equivalent Ni(1) atoms.
CoNiSe2 crystallizes in the trigonal P-3m1 space group. Co(1) is bonded to six equivalent Se(1) atoms to form distorted CoSe6 octahedra that share corners with twelve equivalent Ni(1)Se6 octahedra, edges with six equivalent Co(1)Se6 octahedra, and faces with two equivalent Ni(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 51°. All Co(1)-Se(1) bond lengths are 2.44 Å. Ni(1) is bonded to six equivalent Se(1) atoms to form distorted NiSe6 octahedra that share corners with twelve equivalent Co(1)Se6 octahedra, edges with six equivalent Ni(1)Se6 octahedra, and faces with two equivalent Co(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 51°. All Ni(1)-Se(1) bond lengths are 2.51 Å. Se(1) is bonded in a 6-coordinate geometry to three equivalent Co(1) and three equivalent Ni(1) atoms.