Na2Fe3SbO8 crystallizes in the orthorhombic Pmn2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), two equivalent O(4), two equivalent O(6), and two equivalent O(8) atoms. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to one O(1), one O(2), two equivalent O(3), two equivalent O(5), and two equivalent O(7) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(5), one O(8), two equivalent O(2), and two equivalent O(7) atoms to form FeO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Sb(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-56°. In the second Fe site, Fe(2) is bonded to one O(6), one O(7), two equivalent O(1), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Sb(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-57°. In the third Fe site, Fe(3) is bonded to one O(2), one O(4), two equivalent O(3), and two equivalent O(6) atoms to form distorted FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-57°. Sb(1) is bonded to one O(1), one O(3), two equivalent O(4), and two equivalent O(5) atoms to form SbO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-56°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), two equivalent Fe(2), and one Sb(1) atom to form distorted ONa2Fe2Sb trigonal bipyramids that share corners with four equivalent O(8)Na2Fe3 square pyramids, corners with two equivalent O(1)Na2Fe2Sb trigonal bipyramids, corners with two equivalent O(2)Na2Fe3 trigonal bipyramids, corners with three equivalent O(3)Na2Fe2Sb trigonal bipyramids,  an edgeedge with one O(8)Na2Fe3 square pyramid, edges with two equivalent O(7)Na2Fe3 square pyramids, and edges with two equivalent O(4)Na2FeSb2 trigonal bipyramids. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Fe(3), and two equivalent Fe(1) atoms to form distorted ONa2Fe3 trigonal bipyramids that share corners with four equivalent O(7)Na2Fe3 square pyramids, corners with two equivalent O(1)Na2Fe2Sb trigonal bipyramids, corners with two equivalent O(2)Na2Fe3 trigonal bipyramids, corners with three equivalent O(4)Na2FeSb2 trigonal bipyramids,  an edgeedge with one O(7)Na2Fe3 square pyramid, edges with two equivalent O(8)Na2Fe3 square pyramids, and edges with two equivalent O(3)Na2Fe2Sb trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Na(2), two equivalent Fe(3), and one Sb(1) atom to form distorted ONa2Fe2Sb trigonal bipyramids that share corners with two equivalent O(7)Na2Fe3 square pyramids, corners with three equivalent O(1)Na2Fe2Sb trigonal bipyramids,  an edgeedge with one O(7)Na2Fe3 square pyramid, edges with two equivalent O(3)Na2Fe2Sb trigonal bipyramids, edges with two equivalent O(2)Na2Fe3 trigonal bipyramids, and edges with two equivalent O(4)Na2FeSb2 trigonal bipyramids. In the fourth O site, O(4) is bonded to two equivalent Na(1), one Fe(3), and two equivalent Sb(1) atoms to form distorted ONa2FeSb2 trigonal bipyramids that share corners with two equivalent O(8)Na2Fe3 square pyramids, corners with three equivalent O(2)Na2Fe3 trigonal bipyramids,  an edgeedge with one O(8)Na2Fe3 square pyramid, edges with two equivalent O(1)Na2Fe2Sb trigonal bipyramids, edges with two equivalent O(3)Na2Fe2Sb trigonal bipyramids, and edges with two equivalent O(4)Na2FeSb2 trigonal bipyramids. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to two equivalent Na(2), one Fe(1), and two equivalent Sb(1) atoms. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to two equivalent Na(1), one Fe(2), and two equivalent Fe(3) atoms. In the seventh O site, O(7) is bonded to two equivalent Na(2), one Fe(2), and two equivalent Fe(1) atoms to form ONa2Fe3 square pyramids that share corners with two equivalent O(3)Na2Fe2Sb trigonal bipyramids, corners with four equivalent O(2)Na2Fe3 trigonal bipyramids, edges with two equivalent O(7)Na2Fe3 square pyramids, edges with two equivalent O(8)Na2Fe3 square pyramids,  an edgeedge with one O(3)Na2Fe2Sb trigonal bipyramid,  an edgeedge with one O(2)Na2Fe3 trigonal bipyramid, and edges with two equivalent O(1)Na2Fe2Sb trigonal bipyramids. In the eighth O site, O(8) is bonded to two equivalent Na(1), one Fe(1), and two equivalent Fe(2) atoms to form ONa2Fe3 square pyramids that share corners with two equivalent O(4)Na2FeSb2 trigonal bipyramids, corners with four equivalent O(1)Na2Fe2Sb trigonal bipyramids, edges with two equivalent O(7)Na2Fe3 square pyramids, edges with two equivalent O(8)Na2Fe3 square pyramids,  an edgeedge with one O(1)Na2Fe2Sb trigonal bipyramid,  an edgeedge with one O(4)Na2FeSb2 trigonal bipyramid, and edges with two equivalent O(2)Na2Fe3 trigonal bipyramids.
Na2Fe3SbO8 crystallizes in the orthorhombic Pmn2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), two equivalent O(4), two equivalent O(6), and two equivalent O(8) atoms. The Na(1)-O(1) bond length is 2.72 Å. The Na(1)-O(2) bond length is 2.59 Å. Both Na(1)-O(4) bond lengths are 2.48 Å. Both Na(1)-O(6) bond lengths are 2.60 Å. Both Na(1)-O(8) bond lengths are 2.40 Å. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to one O(1), one O(2), two equivalent O(3), two equivalent O(5), and two equivalent O(7) atoms. The Na(2)-O(1) bond length is 2.66 Å. The Na(2)-O(2) bond length is 2.62 Å. Both Na(2)-O(3) bond lengths are 2.42 Å. Both Na(2)-O(5) bond lengths are 2.78 Å. Both Na(2)-O(7) bond lengths are 2.41 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(5), one O(8), two equivalent O(2), and two equivalent O(7) atoms to form FeO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Sb(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-56°. The Fe(1)-O(5) bond length is 2.32 Å. The Fe(1)-O(8) bond length is 2.02 Å. Both Fe(1)-O(2) bond lengths are 2.04 Å. Both Fe(1)-O(7) bond lengths are 2.03 Å. In the second Fe site, Fe(2) is bonded to one O(6), one O(7), two equivalent O(1), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Sb(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-57°. The Fe(2)-O(6) bond length is 2.11 Å. The Fe(2)-O(7) bond length is 2.08 Å. Both Fe(2)-O(1) bond lengths are 2.10 Å. Both Fe(2)-O(8) bond lengths are 2.02 Å. In the third Fe site, Fe(3) is bonded to one O(2), one O(4), two equivalent O(3), and two equivalent O(6) atoms to form distorted FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-57°. The Fe(3)-O(2) bond length is 1.96 Å. The Fe(3)-O(4) bond length is 2.21 Å. Both Fe(3)-O(3) bond lengths are 2.16 Å. Both Fe(3)-O(6) bond lengths are 2.01 Å. Sb(1) is bonded to one O(1), one O(3), two equivalent O(4), and two equivalent O(5) atoms to form SbO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-56°. The Sb(1)-O(1) bond length is 1.98 Å. The Sb(1)-O(3) bond length is 1.98 Å. Both Sb(1)-O(4) bond lengths are 2.06 Å. Both Sb(1)-O(5) bond lengths are 2.05 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), two equivalent Fe(2), and one Sb(1) atom to form distorted ONa2Fe2Sb trigonal bipyramids that share corners with four equivalent O(8)Na2Fe3 square pyramids, corners with two equivalent O(1)Na2Fe2Sb trigonal bipyramids, corners with two equivalent O(2)Na2Fe3 trigonal bipyramids, corners with three equivalent O(3)Na2Fe2Sb trigonal bipyramids,  an edgeedge with one O(8)Na2Fe3 square pyramid, edges with two equivalent O(7)Na2Fe3 square pyramids, and edges with two equivalent O(4)Na2FeSb2 trigonal bipyramids. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Fe(3), and two equivalent Fe(1) atoms to form distorted ONa2Fe3 trigonal bipyramids that share corners with four equivalent O(7)Na2Fe3 square pyramids, corners with two equivalent O(1)Na2Fe2Sb trigonal bipyramids, corners with two equivalent O(2)Na2Fe3 trigonal bipyramids, corners with three equivalent O(4)Na2FeSb2 trigonal bipyramids,  an edgeedge with one O(7)Na2Fe3 square pyramid, edges with two equivalent O(8)Na2Fe3 square pyramids, and edges with two equivalent O(3)Na2Fe2Sb trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Na(2), two equivalent Fe(3), and one Sb(1) atom to form distorted ONa2Fe2Sb trigonal bipyramids that share corners with two equivalent O(7)Na2Fe3 square pyramids, corners with three equivalent O(1)Na2Fe2Sb trigonal bipyramids,  an edgeedge with one O(7)Na2Fe3 square pyramid, edges with two equivalent O(3)Na2Fe2Sb trigonal bipyramids, edges with two equivalent O(2)Na2Fe3 trigonal bipyramids, and edges with two equivalent O(4)Na2FeSb2 trigonal bipyramids. In the fourth O site, O(4) is bonded to two equivalent Na(1), one Fe(3), and two equivalent Sb(1) atoms to form distorted ONa2FeSb2 trigonal bipyramids that share corners with two equivalent O(8)Na2Fe3 square pyramids, corners with three equivalent O(2)Na2Fe3 trigonal bipyramids,  an edgeedge with one O(8)Na2Fe3 square pyramid, edges with two equivalent O(1)Na2Fe2Sb trigonal bipyramids, edges with two equivalent O(3)Na2Fe2Sb trigonal bipyramids, and edges with two equivalent O(4)Na2FeSb2 trigonal bipyramids. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to two equivalent Na(2), one Fe(1), and two equivalent Sb(1) atoms. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to two equivalent Na(1), one Fe(2), and two equivalent Fe(3) atoms. In the seventh O site, O(7) is bonded to two equivalent Na(2), one Fe(2), and two equivalent Fe(1) atoms to form ONa2Fe3 square pyramids that share corners with two equivalent O(3)Na2Fe2Sb trigonal bipyramids, corners with four equivalent O(2)Na2Fe3 trigonal bipyramids, edges with two equivalent O(7)Na2Fe3 square pyramids, edges with two equivalent O(8)Na2Fe3 square pyramids,  an edgeedge with one O(3)Na2Fe2Sb trigonal bipyramid,  an edgeedge with one O(2)Na2Fe3 trigonal bipyramid, and edges with two equivalent O(1)Na2Fe2Sb trigonal bipyramids. In the eighth O site, O(8) is bonded to two equivalent Na(1), one Fe(1), and two equivalent Fe(2) atoms to form ONa2Fe3 square pyramids that share corners with two equivalent O(4)Na2FeSb2 trigonal bipyramids, corners with four equivalent O(1)Na2Fe2Sb trigonal bipyramids, edges with two equivalent O(7)Na2Fe3 square pyramids, edges with two equivalent O(8)Na2Fe3 square pyramids,  an edgeedge with one O(1)Na2Fe2Sb trigonal bipyramid,  an edgeedge with one O(4)Na2FeSb2 trigonal bipyramid, and edges with two equivalent O(2)Na2Fe3 trigonal bipyramids.