Na2FeCPO7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms. In the second Na site, Na(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form distorted NaO7 pentagonal bipyramids that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one P(1)O4 tetrahedra, and  a faceface with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 65°. Fe(1) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form FeO6 octahedra that share  a cornercorner with one Na(2)O7 pentagonal bipyramid, corners with four equivalent P(1)O4 tetrahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid, and  a faceface with one Na(2)O7 pentagonal bipyramid. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. P(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra, corners with two equivalent Na(2)O7 pentagonal bipyramids, and  an edgeedge with one Na(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 34-43°. There are seven inequivalent O sites. In the first O site, O(7) is bonded in a 3-coordinate geometry to one Na(2), one Fe(1), and one P(1) atom. In the second O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one C(1) atom. In the third O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Fe(1), and one C(1) atom. In the fourth O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Fe(1), and one C(1) atom. In the fifth O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Fe(1), and one P(1) atom. In the sixth O site, O(5) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Fe(1), and one P(1) atom. In the seventh O site, O(6) is bonded in a 3-coordinate geometry to one Na(2), one Fe(1), and one P(1) atom.
Na2FeCPO7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms. The Na(1)-O(2) bond length is 2.38 Å. The Na(1)-O(3) bond length is 2.65 Å. The Na(1)-O(4) bond length is 2.47 Å. The Na(1)-O(5) bond length is 2.54 Å. There is one shorter (2.45 Å) and one longer (2.79 Å) Na(1)-O(1) bond length. In the second Na site, Na(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form distorted NaO7 pentagonal bipyramids that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one P(1)O4 tetrahedra, and  a faceface with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 65°. The Na(2)-O(1) bond length is 2.24 Å. The Na(2)-O(2) bond length is 2.55 Å. The Na(2)-O(3) bond length is 2.41 Å. The Na(2)-O(4) bond length is 2.73 Å. The Na(2)-O(5) bond length is 2.56 Å. The Na(2)-O(6) bond length is 2.35 Å. The Na(2)-O(7) bond length is 2.57 Å. Fe(1) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(7) atom to form FeO6 octahedra that share  a cornercorner with one Na(2)O7 pentagonal bipyramid, corners with four equivalent P(1)O4 tetrahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid, and  a faceface with one Na(2)O7 pentagonal bipyramid. The Fe(1)-O(2) bond length is 2.15 Å. The Fe(1)-O(3) bond length is 2.15 Å. The Fe(1)-O(4) bond length is 2.02 Å. The Fe(1)-O(5) bond length is 2.08 Å. The Fe(1)-O(6) bond length is 1.97 Å. The Fe(1)-O(7) bond length is 1.97 Å. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. The C(1)-O(1) bond length is 1.27 Å. The C(1)-O(2) bond length is 1.32 Å. The C(1)-O(3) bond length is 1.31 Å. P(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra, corners with two equivalent Na(2)O7 pentagonal bipyramids, and  an edgeedge with one Na(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 34-43°. The P(1)-O(4) bond length is 1.55 Å. The P(1)-O(5) bond length is 1.55 Å. The P(1)-O(6) bond length is 1.55 Å. The P(1)-O(7) bond length is 1.56 Å. There are seven inequivalent O sites. In the first O site, O(7) is bonded in a 3-coordinate geometry to one Na(2), one Fe(1), and one P(1) atom. In the second O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one C(1) atom. In the third O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Fe(1), and one C(1) atom. In the fourth O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Fe(1), and one C(1) atom. In the fifth O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Fe(1), and one P(1) atom. In the sixth O site, O(5) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Fe(1), and one P(1) atom. In the seventh O site, O(6) is bonded in a 3-coordinate geometry to one Na(2), one Fe(1), and one P(1) atom.