Na3Fe2(MoO4)3 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 square co-planar geometry to four equivalent O(4) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. In the third Na site, Na(3) is bonded in a distorted hexagonal planar geometry to two equivalent O(5) and four equivalent O(2) atoms. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form MoO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-61°. In the second Mo site, Mo(2) is bonded to two equivalent O(1) and two equivalent O(5) atoms to form MoO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 60°. Fe(1) is bonded to one O(1), one O(3), one O(4), one O(5), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Mo(2)O4 tetrahedra, corners with four equivalent Mo(1)O4 tetrahedra, and  an edgeedge with one Fe(1)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Na(2), one Mo(2), and one Fe(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), two equivalent Na(3), and one Mo(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2), one Mo(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded to two equivalent Na(1), one Mo(1), and one Fe(1) atom to form a mixture of distorted corner and edge-sharing ONa2FeMo tetrahedra. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Na(3), one Mo(2), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Mo(1) and two equivalent Fe(1) atoms.
Na3Fe2(MoO4)3 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 square co-planar geometry to four equivalent O(4) atoms. There are two shorter (2.49 Å) and two longer (2.53 Å) Na(1)-O(4) bond lengths. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Both Na(2)-O(1) bond lengths are 2.45 Å. Both Na(2)-O(2) bond lengths are 2.47 Å. Both Na(2)-O(3) bond lengths are 2.38 Å. In the third Na site, Na(3) is bonded in a distorted hexagonal planar geometry to two equivalent O(5) and four equivalent O(2) atoms. Both Na(3)-O(5) bond lengths are 2.49 Å. There are two shorter (2.43 Å) and two longer (2.72 Å) Na(3)-O(2) bond lengths. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form MoO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-61°. The Mo(1)-O(2) bond length is 1.77 Å. The Mo(1)-O(3) bond length is 1.80 Å. The Mo(1)-O(4) bond length is 1.82 Å. The Mo(1)-O(6) bond length is 1.82 Å. In the second Mo site, Mo(2) is bonded to two equivalent O(1) and two equivalent O(5) atoms to form MoO4 tetrahedra that share corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 60°. Both Mo(2)-O(1) bond lengths are 1.88 Å. Both Mo(2)-O(5) bond lengths are 1.88 Å. Fe(1) is bonded to one O(1), one O(3), one O(4), one O(5), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Mo(2)O4 tetrahedra, corners with four equivalent Mo(1)O4 tetrahedra, and  an edgeedge with one Fe(1)O6 octahedra. The Fe(1)-O(1) bond length is 2.05 Å. The Fe(1)-O(3) bond length is 2.17 Å. The Fe(1)-O(4) bond length is 2.26 Å. The Fe(1)-O(5) bond length is 2.04 Å. There is one shorter (2.25 Å) and one longer (2.33 Å) Fe(1)-O(6) bond length. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Na(2), one Mo(2), and one Fe(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), two equivalent Na(3), and one Mo(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2), one Mo(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded to two equivalent Na(1), one Mo(1), and one Fe(1) atom to form a mixture of distorted corner and edge-sharing ONa2FeMo tetrahedra. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Na(3), one Mo(2), and one Fe(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Mo(1) and two equivalent Fe(1) atoms.