NaCuFeS2 crystallizes in the trigonal P3m1 space group. Na(1) is bonded to three equivalent S(1) and three equivalent S(2) atoms to form NaS6 octahedra that share corners with six equivalent Fe(1)S4 tetrahedra, corners with six equivalent Cu(1)S4 tetrahedra, edges with six equivalent Na(1)S6 octahedra, edges with three equivalent Fe(1)S4 tetrahedra, and edges with three equivalent Cu(1)S4 tetrahedra. Fe(1) is bonded to one S(1) and three equivalent S(2) atoms to form FeS4 tetrahedra that share corners with six equivalent Na(1)S6 octahedra, corners with six equivalent Fe(1)S4 tetrahedra, edges with three equivalent Na(1)S6 octahedra, and edges with three equivalent Cu(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-50°. Cu(1) is bonded to one S(2) and three equivalent S(1) atoms to form CuS4 tetrahedra that share corners with six equivalent Na(1)S6 octahedra, corners with six equivalent Cu(1)S4 tetrahedra, edges with three equivalent Na(1)S6 octahedra, and edges with three equivalent Fe(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-49°. There are two inequivalent S sites. In the first S site, S(1) is bonded to three equivalent Na(1), one Fe(1), and three equivalent Cu(1) atoms to form distorted SNa3FeCu3 pentagonal bipyramids that share corners with three equivalent S(2)Na3Fe3Cu pentagonal bipyramids, edges with six equivalent S(2)Na3Fe3Cu pentagonal bipyramids, and edges with six equivalent S(1)Na3FeCu3 pentagonal bipyramids. In the second S site, S(2) is bonded to three equivalent Na(1), three equivalent Fe(1), and one Cu(1) atom to form distorted SNa3Fe3Cu pentagonal bipyramids that share corners with three equivalent S(1)Na3FeCu3 pentagonal bipyramids, edges with six equivalent S(2)Na3Fe3Cu pentagonal bipyramids, and edges with six equivalent S(1)Na3FeCu3 pentagonal bipyramids.
NaCuFeS2 crystallizes in the trigonal P3m1 space group. Na(1) is bonded to three equivalent S(1) and three equivalent S(2) atoms to form NaS6 octahedra that share corners with six equivalent Fe(1)S4 tetrahedra, corners with six equivalent Cu(1)S4 tetrahedra, edges with six equivalent Na(1)S6 octahedra, edges with three equivalent Fe(1)S4 tetrahedra, and edges with three equivalent Cu(1)S4 tetrahedra. All Na(1)-S(1) bond lengths are 2.89 Å. All Na(1)-S(2) bond lengths are 2.93 Å. Fe(1) is bonded to one S(1) and three equivalent S(2) atoms to form FeS4 tetrahedra that share corners with six equivalent Na(1)S6 octahedra, corners with six equivalent Fe(1)S4 tetrahedra, edges with three equivalent Na(1)S6 octahedra, and edges with three equivalent Cu(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-50°. The Fe(1)-S(1) bond length is 2.33 Å. All Fe(1)-S(2) bond lengths are 2.36 Å. Cu(1) is bonded to one S(2) and three equivalent S(1) atoms to form CuS4 tetrahedra that share corners with six equivalent Na(1)S6 octahedra, corners with six equivalent Cu(1)S4 tetrahedra, edges with three equivalent Na(1)S6 octahedra, and edges with three equivalent Fe(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-49°. The Cu(1)-S(2) bond length is 2.40 Å. All Cu(1)-S(1) bond lengths are 2.34 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded to three equivalent Na(1), one Fe(1), and three equivalent Cu(1) atoms to form distorted SNa3FeCu3 pentagonal bipyramids that share corners with three equivalent S(2)Na3Fe3Cu pentagonal bipyramids, edges with six equivalent S(2)Na3Fe3Cu pentagonal bipyramids, and edges with six equivalent S(1)Na3FeCu3 pentagonal bipyramids. In the second S site, S(2) is bonded to three equivalent Na(1), three equivalent Fe(1), and one Cu(1) atom to form distorted SNa3Fe3Cu pentagonal bipyramids that share corners with three equivalent S(1)Na3FeCu3 pentagonal bipyramids, edges with six equivalent S(2)Na3Fe3Cu pentagonal bipyramids, and edges with six equivalent S(1)Na3FeCu3 pentagonal bipyramids.