Na3FeCAsO7 crystallizes in the monoclinic P2_1/m 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), two equivalent O(1), and two equivalent O(6) 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), and two equivalent O(6) atoms to form distorted NaO7 pentagonal bipyramids that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Na(2)O7 pentagonal bipyramids, corners with two equivalent As(1)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid,  an edgeedge with one As(1)O4 tetrahedra,  a faceface with one Fe(1)O6 octahedra, and  a faceface with one Na(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 56°. Fe(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(6) atoms to form distorted FeO6 octahedra that share corners with two equivalent Na(2)O7 pentagonal bipyramids, corners with four equivalent As(1)O4 tetrahedra, edges with two equivalent Na(2)O7 pentagonal bipyramids, and faces with two equivalent Na(2)O7 pentagonal bipyramids. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. As(1) is bonded to one O(4), one O(5), and two equivalent O(6) atoms to form AsO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra, corners with four equivalent Na(2)O7 pentagonal bipyramids, and edges with two equivalent Na(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 43-62°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one C(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Fe(1), and one C(1) atom. In the third O site, O(3) is bonded to one Na(1), two equivalent Na(2), one Fe(1), and one C(1) atom to form distorted corner-sharing ONa3FeC trigonal bipyramids. In the fourth O site, O(4) is bonded to two equivalent Na(2), one Fe(1), and one As(1) atom to form distorted corner-sharing ONa2FeAs tetrahedra. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to two equivalent Na(2), one Fe(1), and one As(1) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Fe(1), and one As(1) atom.
Na3FeCAsO7 crystallizes in the monoclinic P2_1/m 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), two equivalent O(1), and two equivalent O(6) atoms. The Na(1)-O(2) bond length is 2.33 Å. The Na(1)-O(3) bond length is 2.45 Å. There is one shorter (2.47 Å) and one longer (2.68 Å) Na(1)-O(1) bond length. Both Na(1)-O(6) bond lengths are 2.45 Å. 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), and two equivalent O(6) atoms to form distorted NaO7 pentagonal bipyramids that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Na(2)O7 pentagonal bipyramids, corners with two equivalent As(1)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid,  an edgeedge with one As(1)O4 tetrahedra,  a faceface with one Fe(1)O6 octahedra, and  a faceface with one Na(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 56°. The Na(2)-O(1) bond length is 2.29 Å. The Na(2)-O(2) bond length is 2.61 Å. The Na(2)-O(3) bond length is 2.41 Å. The Na(2)-O(4) bond length is 2.46 Å. The Na(2)-O(5) bond length is 2.29 Å. There is one shorter (2.50 Å) and one longer (2.77 Å) Na(2)-O(6) bond length. Fe(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(6) atoms to form distorted FeO6 octahedra that share corners with two equivalent Na(2)O7 pentagonal bipyramids, corners with four equivalent As(1)O4 tetrahedra, edges with two equivalent Na(2)O7 pentagonal bipyramids, and faces with two equivalent Na(2)O7 pentagonal bipyramids. The Fe(1)-O(2) bond length is 2.22 Å. The Fe(1)-O(3) bond length is 2.38 Å. The Fe(1)-O(4) bond length is 2.10 Å. The Fe(1)-O(5) bond length is 2.09 Å. Both Fe(1)-O(6) bond lengths are 2.04 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 1.29 Å. The C(1)-O(2) bond length is 1.30 Å. The C(1)-O(3) bond length is 1.29 Å. As(1) is bonded to one O(4), one O(5), and two equivalent O(6) atoms to form AsO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra, corners with four equivalent Na(2)O7 pentagonal bipyramids, and edges with two equivalent Na(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 43-62°. The As(1)-O(4) bond length is 1.71 Å. The As(1)-O(5) bond length is 1.69 Å. Both As(1)-O(6) bond lengths are 1.71 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one C(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Fe(1), and one C(1) atom. In the third O site, O(3) is bonded to one Na(1), two equivalent Na(2), one Fe(1), and one C(1) atom to form distorted corner-sharing ONa3FeC trigonal bipyramids. In the fourth O site, O(4) is bonded to two equivalent Na(2), one Fe(1), and one As(1) atom to form distorted corner-sharing ONa2FeAs tetrahedra. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to two equivalent Na(2), one Fe(1), and one As(1) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Fe(1), and one As(1) atom.