FeNiS2 is Modderite-derived structured and crystallizes in the trigonal P-3m1 space group. Fe(1) is bonded to six equivalent S(1) atoms to form distorted FeS6 octahedra that share corners with twelve equivalent Ni(1)S6 octahedra, edges with six equivalent Fe(1)S6 octahedra, and faces with two equivalent Ni(1)S6 octahedra. The corner-sharing octahedral tilt angles are 50°. Ni(1) is bonded to six equivalent S(1) atoms to form distorted NiS6 octahedra that share corners with twelve equivalent Fe(1)S6 octahedra, edges with six equivalent Ni(1)S6 octahedra, and faces with two equivalent Fe(1)S6 octahedra. The corner-sharing octahedral tilt angles are 50°. S(1) is bonded in a 6-coordinate geometry to three equivalent Fe(1) and three equivalent Ni(1) atoms.
FeNiS2 is Modderite-derived structured and crystallizes in the trigonal P-3m1 space group. Fe(1) is bonded to six equivalent S(1) atoms to form distorted FeS6 octahedra that share corners with twelve equivalent Ni(1)S6 octahedra, edges with six equivalent Fe(1)S6 octahedra, and faces with two equivalent Ni(1)S6 octahedra. The corner-sharing octahedral tilt angles are 50°. All Fe(1)-S(1) bond lengths are 2.31 Å. Ni(1) is bonded to six equivalent S(1) atoms to form distorted NiS6 octahedra that share corners with twelve equivalent Fe(1)S6 octahedra, edges with six equivalent Ni(1)S6 octahedra, and faces with two equivalent Fe(1)S6 octahedra. The corner-sharing octahedral tilt angles are 50°. All Ni(1)-S(1) bond lengths are 2.40 Å. S(1) is bonded in a 6-coordinate geometry to three equivalent Fe(1) and three equivalent Ni(1) atoms.