Na2FeCuF7 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to two equivalent F(2), two equivalent F(3), two equivalent F(4), and two equivalent F(7) atoms. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to two equivalent F(2), two equivalent F(4), two equivalent F(5), and two equivalent F(6) atoms. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one F(1), one F(2), one F(3), one F(6), one F(7), and two equivalent F(5) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent F(4), two equivalent F(5), and two equivalent F(7) atoms to form FeF6 octahedra that share corners with two equivalent Cu(1)F6 octahedra and corners with two equivalent Cu(2)F6 octahedra. The corner-sharing octahedral tilt angles range from 43-48°. In the second Fe site, Fe(2) is bonded to two equivalent F(1), two equivalent F(2), and two equivalent F(6) atoms to form FeF6 octahedra that share corners with two equivalent Cu(1)F6 octahedra and corners with two equivalent Cu(2)F6 octahedra. The corner-sharing octahedral tilt angles range from 38-51°. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent F(1), two equivalent F(3), and two equivalent F(7) atoms to form CuF6 octahedra that share corners with two equivalent Fe(1)F6 octahedra, corners with two equivalent Fe(2)F6 octahedra, and corners with two equivalent Cu(2)F6 octahedra. The corner-sharing octahedral tilt angles range from 38-48°. In the second Cu site, Cu(2) is bonded to two equivalent F(3), two equivalent F(4), and two equivalent F(6) atoms to form CuF6 octahedra that share corners with two equivalent Fe(1)F6 octahedra, corners with two equivalent Fe(2)F6 octahedra, and corners with two equivalent Cu(1)F6 octahedra. The corner-sharing octahedral tilt angles range from 43-51°. There are seven inequivalent F sites. In the first F site, F(1) is bonded in a 3-coordinate geometry to one Na(3), one Fe(2), and one Cu(1) atom. In the second F site, F(7) is bonded in a 4-coordinate geometry to one Na(1), one Na(3), one Fe(1), and one Cu(1) atom. In the third F site, F(2) is bonded to one Na(1), one Na(2), one Na(3), and one Fe(2) atom to form a mixture of edge and corner-sharing FNa3Fe tetrahedra. In the fourth F site, F(3) is bonded in a 2-coordinate geometry to one Na(1), one Na(3), one Cu(1), and one Cu(2) atom. In the fifth F site, F(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Fe(1), and one Cu(2) atom. In the sixth F site, F(5) is bonded to one Na(2), two equivalent Na(3), and one Fe(1) atom to form a mixture of distorted edge and corner-sharing FNa3Fe tetrahedra. In the seventh F site, F(6) is bonded in a 4-coordinate geometry to one Na(2), one Na(3), one Fe(2), and one Cu(2) atom.
Na2FeCuF7 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to two equivalent F(2), two equivalent F(3), two equivalent F(4), and two equivalent F(7) atoms. Both Na(1)-F(2) bond lengths are 2.19 Å. Both Na(1)-F(3) bond lengths are 2.90 Å. Both Na(1)-F(4) bond lengths are 2.66 Å. Both Na(1)-F(7) bond lengths are 2.45 Å. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to two equivalent F(2), two equivalent F(4), two equivalent F(5), and two equivalent F(6) atoms. Both Na(2)-F(2) bond lengths are 2.46 Å. Both Na(2)-F(4) bond lengths are 2.72 Å. Both Na(2)-F(5) bond lengths are 2.49 Å. Both Na(2)-F(6) bond lengths are 2.85 Å. In the third Na site, Na(3) is bonded in a 7-coordinate geometry to one F(1), one F(2), one F(3), one F(6), one F(7), and two equivalent F(5) atoms. The Na(3)-F(1) bond length is 2.47 Å. The Na(3)-F(2) bond length is 2.44 Å. The Na(3)-F(3) bond length is 2.69 Å. The Na(3)-F(6) bond length is 2.43 Å. The Na(3)-F(7) bond length is 2.78 Å. There is one shorter (2.33 Å) and one longer (2.43 Å) Na(3)-F(5) bond length. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent F(4), two equivalent F(5), and two equivalent F(7) atoms to form FeF6 octahedra that share corners with two equivalent Cu(1)F6 octahedra and corners with two equivalent Cu(2)F6 octahedra. The corner-sharing octahedral tilt angles range from 43-48°. Both Fe(1)-F(4) bond lengths are 1.98 Å. Both Fe(1)-F(5) bond lengths are 1.98 Å. Both Fe(1)-F(7) bond lengths are 1.94 Å. In the second Fe site, Fe(2) is bonded to two equivalent F(1), two equivalent F(2), and two equivalent F(6) atoms to form FeF6 octahedra that share corners with two equivalent Cu(1)F6 octahedra and corners with two equivalent Cu(2)F6 octahedra. The corner-sharing octahedral tilt angles range from 38-51°. Both Fe(2)-F(1) bond lengths are 1.98 Å. Both Fe(2)-F(2) bond lengths are 1.96 Å. Both Fe(2)-F(6) bond lengths are 1.95 Å. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent F(1), two equivalent F(3), and two equivalent F(7) atoms to form CuF6 octahedra that share corners with two equivalent Fe(1)F6 octahedra, corners with two equivalent Fe(2)F6 octahedra, and corners with two equivalent Cu(2)F6 octahedra. The corner-sharing octahedral tilt angles range from 38-48°. Both Cu(1)-F(1) bond lengths are 1.94 Å. Both Cu(1)-F(3) bond lengths are 1.98 Å. Both Cu(1)-F(7) bond lengths are 2.14 Å. In the second Cu site, Cu(2) is bonded to two equivalent F(3), two equivalent F(4), and two equivalent F(6) atoms to form CuF6 octahedra that share corners with two equivalent Fe(1)F6 octahedra, corners with two equivalent Fe(2)F6 octahedra, and corners with two equivalent Cu(1)F6 octahedra. The corner-sharing octahedral tilt angles range from 43-51°. Both Cu(2)-F(3) bond lengths are 1.95 Å. Both Cu(2)-F(4) bond lengths are 1.95 Å. Both Cu(2)-F(6) bond lengths are 2.25 Å. There are seven inequivalent F sites. In the first F site, F(1) is bonded in a 3-coordinate geometry to one Na(3), one Fe(2), and one Cu(1) atom. In the second F site, F(7) is bonded in a 4-coordinate geometry to one Na(1), one Na(3), one Fe(1), and one Cu(1) atom. In the third F site, F(2) is bonded to one Na(1), one Na(2), one Na(3), and one Fe(2) atom to form a mixture of edge and corner-sharing FNa3Fe tetrahedra. In the fourth F site, F(3) is bonded in a 2-coordinate geometry to one Na(1), one Na(3), one Cu(1), and one Cu(2) atom. In the fifth F site, F(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Fe(1), and one Cu(2) atom. In the sixth F site, F(5) is bonded to one Na(2), two equivalent Na(3), and one Fe(1) atom to form a mixture of distorted edge and corner-sharing FNa3Fe tetrahedra. In the seventh F site, F(6) is bonded in a 4-coordinate geometry to one Na(2), one Na(3), one Fe(2), and one Cu(2) atom.