CuFe2(P2O7)2 crystallizes in the monoclinic P2_1/c space group. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(7) atom to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. Cu(1) is bonded in a square co-planar geometry to two equivalent O(5) and two equivalent O(7) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 16-50°. In the second P site, P(2) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 16-49°. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(7) is bonded in a distorted trigonal planar geometry to one Fe(1), one Cu(1), and one P(1) atom. In the third O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the fourth O site, O(2) is bonded in a linear geometry to one Fe(1) and one P(2) atom. In the fifth O site, O(3) is bonded in a linear geometry to one Fe(1) and one P(1) atom. In the sixth O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the seventh O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Cu(1), and one P(2) atom.
CuFe2(P2O7)2 crystallizes in the monoclinic P2_1/c space group. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(7) atom to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. The Fe(1)-O(1) bond length is 1.95 Å. The Fe(1)-O(2) bond length is 1.98 Å. The Fe(1)-O(3) bond length is 1.95 Å. The Fe(1)-O(4) bond length is 1.99 Å. The Fe(1)-O(5) bond length is 2.17 Å. The Fe(1)-O(7) bond length is 2.12 Å. Cu(1) is bonded in a square co-planar geometry to two equivalent O(5) and two equivalent O(7) atoms. Both Cu(1)-O(5) bond lengths are 1.97 Å. Both Cu(1)-O(7) bond lengths are 1.94 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 16-50°. The P(1)-O(3) bond length is 1.50 Å. The P(1)-O(4) bond length is 1.51 Å. The P(1)-O(6) bond length is 1.61 Å. The P(1)-O(7) bond length is 1.57 Å. In the second P site, P(2) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 16-49°. The P(2)-O(1) bond length is 1.52 Å. The P(2)-O(2) bond length is 1.51 Å. The P(2)-O(5) bond length is 1.57 Å. The P(2)-O(6) bond length is 1.62 Å. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the second O site, O(7) is bonded in a distorted trigonal planar geometry to one Fe(1), one Cu(1), and one P(1) atom. In the third O site, O(1) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the fourth O site, O(2) is bonded in a linear geometry to one Fe(1) and one P(2) atom. In the fifth O site, O(3) is bonded in a linear geometry to one Fe(1) and one P(1) atom. In the sixth O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the seventh O site, O(5) is bonded in a distorted trigonal planar geometry to one Fe(1), one Cu(1), and one P(2) atom.