Na8FeO6 crystallizes in the monoclinic Cc space group. There are eight inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form NaO4 tetrahedra that share  a cornercorner with one Na(5)O4 tetrahedra, corners with two equivalent Na(2)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with three equivalent Na(4)O4 tetrahedra, corners with three equivalent Na(7)O4 tetrahedra,  an edgeedge with one Na(2)O4 tetrahedra,  an edgeedge with one Na(3)O4 tetrahedra,  an edgeedge with one Na(5)O4 tetrahedra, and  an edgeedge with one Na(8)O4 tetrahedra. In the second Na site, Na(2) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form distorted NaO4 tetrahedra that share  a cornercorner with one Na(4)O4 tetrahedra,  a cornercorner with one Na(7)O4 tetrahedra, corners with two equivalent Na(1)O4 tetrahedra, corners with two equivalent Na(3)O4 tetrahedra, corners with two equivalent Na(8)O4 tetrahedra, corners with three equivalent Na(5)O4 tetrahedra,  an edgeedge with one Na(1)O4 tetrahedra,  an edgeedge with one Na(4)O4 tetrahedra,  an edgeedge with one Na(7)O4 tetrahedra, and  an edgeedge with one Fe(1)O4 tetrahedra. In the third Na site, Na(3) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form NaO4 tetrahedra that share corners with two equivalent Na(2)O4 tetrahedra, corners with two equivalent Na(5)O4 tetrahedra, corners with three equivalent Na(8)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra,  an edgeedge with one Na(1)O4 tetrahedra,  an edgeedge with one Na(4)O4 tetrahedra, and  an edgeedge with one Na(7)O4 tetrahedra. In the fourth Na site, Na(4) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form NaO4 tetrahedra that share  a cornercorner with one Na(2)O4 tetrahedra, corners with two equivalent Na(5)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with three equivalent Na(1)O4 tetrahedra, corners with three equivalent Na(7)O4 tetrahedra,  an edgeedge with one Na(2)O4 tetrahedra,  an edgeedge with one Na(3)O4 tetrahedra,  an edgeedge with one Na(5)O4 tetrahedra, and  an edgeedge with one Na(8)O4 tetrahedra. In the fifth Na site, Na(5) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form distorted NaO4 tetrahedra that share  a cornercorner with one Na(1)O4 tetrahedra,  a cornercorner with one Na(7)O4 tetrahedra, corners with two equivalent Na(3)O4 tetrahedra, corners with two equivalent Na(4)O4 tetrahedra, corners with two equivalent Na(8)O4 tetrahedra, corners with three equivalent Na(2)O4 tetrahedra,  an edgeedge with one Na(1)O4 tetrahedra,  an edgeedge with one Na(4)O4 tetrahedra,  an edgeedge with one Na(7)O4 tetrahedra, and  an edgeedge with one Fe(1)O4 tetrahedra. In the sixth Na site, Na(6) is bonded in a 4-coordinate geometry to one O(2), one O(3), one O(5), and one O(6) atom. In the seventh Na site, Na(7) is bonded to one O(2), one O(3), one O(5), and one O(6) atom to form NaO4 tetrahedra that share  a cornercorner with one Na(2)O4 tetrahedra,  a cornercorner with one Na(5)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with three equivalent Na(1)O4 tetrahedra, corners with three equivalent Na(4)O4 tetrahedra,  an edgeedge with one Na(2)O4 tetrahedra,  an edgeedge with one Na(3)O4 tetrahedra,  an edgeedge with one Na(5)O4 tetrahedra, and  an edgeedge with one Na(8)O4 tetrahedra. In the eighth Na site, Na(8) is bonded to one O(1), one O(4), one O(5), and one O(6) atom to form NaO4 tetrahedra that share corners with two equivalent Na(2)O4 tetrahedra, corners with two equivalent Na(5)O4 tetrahedra, corners with three equivalent Na(3)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra,  an edgeedge with one Na(1)O4 tetrahedra,  an edgeedge with one Na(4)O4 tetrahedra, and  an edgeedge with one Na(7)O4 tetrahedra. Fe(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form FeO4 tetrahedra that share corners with two equivalent Na(1)O4 tetrahedra, corners with two equivalent Na(4)O4 tetrahedra, corners with two equivalent Na(7)O4 tetrahedra, corners with three equivalent Na(3)O4 tetrahedra, corners with three equivalent Na(8)O4 tetrahedra,  an edgeedge with one Na(2)O4 tetrahedra, and  an edgeedge with one Na(5)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Na(3), one Na(8), and one Fe(1) atom to form distorted ONa4Fe trigonal bipyramids that share  a cornercorner with one O(2)Na7 pentagonal bipyramid,  a cornercorner with one O(6)Na7 pentagonal bipyramid, corners with three equivalent O(4)Na4Fe trigonal bipyramids, corners with three equivalent O(5)Na4Fe trigonal bipyramids,  an edgeedge with one O(2)Na7 pentagonal bipyramid, and  an edgeedge with one O(6)Na7 pentagonal bipyramid. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Na(5), one Na(6), and one Na(7) atom to form distorted ONa7 pentagonal bipyramids that share  a cornercorner with one O(1)Na4Fe trigonal bipyramid,  a cornercorner with one O(4)Na4Fe trigonal bipyramid,  a cornercorner with one O(5)Na4Fe trigonal bipyramid, edges with three equivalent O(6)Na7 pentagonal bipyramids,  an edgeedge with one O(1)Na4Fe trigonal bipyramid,  an edgeedge with one O(4)Na4Fe trigonal bipyramid, and  an edgeedge with one O(5)Na4Fe trigonal bipyramid. In the third O site, O(3) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(4), one Na(5), one Na(6), one Na(7), and one Fe(1) atom. In the fourth O site, O(4) is bonded to one Na(3), one Na(4), one Na(5), one Na(8), and one Fe(1) atom to form distorted ONa4Fe trigonal bipyramids that share  a cornercorner with one O(2)Na7 pentagonal bipyramid,  a cornercorner with one O(6)Na7 pentagonal bipyramid, corners with three equivalent O(1)Na4Fe trigonal bipyramids, corners with three equivalent O(5)Na4Fe trigonal bipyramids,  an edgeedge with one O(2)Na7 pentagonal bipyramid, and  an edgeedge with one O(6)Na7 pentagonal bipyramid. In the fifth O site, O(5) is bonded to one Na(3), one Na(6), one Na(7), one Na(8), and one Fe(1) atom to form distorted ONa4Fe trigonal bipyramids that share  a cornercorner with one O(2)Na7 pentagonal bipyramid,  a cornercorner with one O(6)Na7 pentagonal bipyramid, corners with three equivalent O(1)Na4Fe trigonal bipyramids, corners with three equivalent O(4)Na4Fe trigonal bipyramids,  an edgeedge with one O(2)Na7 pentagonal bipyramid, and  an edgeedge with one O(6)Na7 pentagonal bipyramid. In the sixth O site, O(6) is bonded to one Na(1), one Na(2), one Na(4), one Na(5), one Na(6), one Na(7), and one Na(8) atom to form distorted ONa7 pentagonal bipyramids that share  a cornercorner with one O(1)Na4Fe trigonal bipyramid,  a cornercorner with one O(4)Na4Fe trigonal bipyramid,  a cornercorner with one O(5)Na4Fe trigonal bipyramid, edges with three equivalent O(2)Na7 pentagonal bipyramids,  an edgeedge with one O(1)Na4Fe trigonal bipyramid,  an edgeedge with one O(4)Na4Fe trigonal bipyramid, and  an edgeedge with one O(5)Na4Fe trigonal bipyramid.
Na8FeO6 crystallizes in the monoclinic Cc space group. There are eight inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form NaO4 tetrahedra that share  a cornercorner with one Na(5)O4 tetrahedra, corners with two equivalent Na(2)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with three equivalent Na(4)O4 tetrahedra, corners with three equivalent Na(7)O4 tetrahedra,  an edgeedge with one Na(2)O4 tetrahedra,  an edgeedge with one Na(3)O4 tetrahedra,  an edgeedge with one Na(5)O4 tetrahedra, and  an edgeedge with one Na(8)O4 tetrahedra. The Na(1)-O(1) bond length is 2.31 Å. The Na(1)-O(2) bond length is 2.30 Å. The Na(1)-O(3) bond length is 2.48 Å. The Na(1)-O(6) bond length is 2.30 Å. In the second Na site, Na(2) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form distorted NaO4 tetrahedra that share  a cornercorner with one Na(4)O4 tetrahedra,  a cornercorner with one Na(7)O4 tetrahedra, corners with two equivalent Na(1)O4 tetrahedra, corners with two equivalent Na(3)O4 tetrahedra, corners with two equivalent Na(8)O4 tetrahedra, corners with three equivalent Na(5)O4 tetrahedra,  an edgeedge with one Na(1)O4 tetrahedra,  an edgeedge with one Na(4)O4 tetrahedra,  an edgeedge with one Na(7)O4 tetrahedra, and  an edgeedge with one Fe(1)O4 tetrahedra. The Na(2)-O(1) bond length is 2.26 Å. The Na(2)-O(2) bond length is 2.29 Å. The Na(2)-O(3) bond length is 2.43 Å. The Na(2)-O(6) bond length is 2.28 Å. In the third Na site, Na(3) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form NaO4 tetrahedra that share corners with two equivalent Na(2)O4 tetrahedra, corners with two equivalent Na(5)O4 tetrahedra, corners with three equivalent Na(8)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra,  an edgeedge with one Na(1)O4 tetrahedra,  an edgeedge with one Na(4)O4 tetrahedra, and  an edgeedge with one Na(7)O4 tetrahedra. The Na(3)-O(1) bond length is 2.40 Å. The Na(3)-O(2) bond length is 2.37 Å. The Na(3)-O(4) bond length is 2.30 Å. The Na(3)-O(5) bond length is 2.37 Å. In the fourth Na site, Na(4) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form NaO4 tetrahedra that share  a cornercorner with one Na(2)O4 tetrahedra, corners with two equivalent Na(5)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with three equivalent Na(1)O4 tetrahedra, corners with three equivalent Na(7)O4 tetrahedra,  an edgeedge with one Na(2)O4 tetrahedra,  an edgeedge with one Na(3)O4 tetrahedra,  an edgeedge with one Na(5)O4 tetrahedra, and  an edgeedge with one Na(8)O4 tetrahedra. The Na(4)-O(2) bond length is 2.30 Å. The Na(4)-O(3) bond length is 2.40 Å. The Na(4)-O(4) bond length is 2.31 Å. The Na(4)-O(6) bond length is 2.28 Å. In the fifth Na site, Na(5) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form distorted NaO4 tetrahedra that share  a cornercorner with one Na(1)O4 tetrahedra,  a cornercorner with one Na(7)O4 tetrahedra, corners with two equivalent Na(3)O4 tetrahedra, corners with two equivalent Na(4)O4 tetrahedra, corners with two equivalent Na(8)O4 tetrahedra, corners with three equivalent Na(2)O4 tetrahedra,  an edgeedge with one Na(1)O4 tetrahedra,  an edgeedge with one Na(4)O4 tetrahedra,  an edgeedge with one Na(7)O4 tetrahedra, and  an edgeedge with one Fe(1)O4 tetrahedra. The Na(5)-O(2) bond length is 2.29 Å. The Na(5)-O(3) bond length is 2.40 Å. The Na(5)-O(4) bond length is 2.26 Å. The Na(5)-O(6) bond length is 2.30 Å. In the sixth Na site, Na(6) is bonded in a 4-coordinate geometry to one O(2), one O(3), one O(5), and one O(6) atom. The Na(6)-O(2) bond length is 2.28 Å. The Na(6)-O(3) bond length is 2.52 Å. The Na(6)-O(5) bond length is 2.33 Å. The Na(6)-O(6) bond length is 2.29 Å. In the seventh Na site, Na(7) is bonded to one O(2), one O(3), one O(5), and one O(6) atom to form NaO4 tetrahedra that share  a cornercorner with one Na(2)O4 tetrahedra,  a cornercorner with one Na(5)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, corners with three equivalent Na(1)O4 tetrahedra, corners with three equivalent Na(4)O4 tetrahedra,  an edgeedge with one Na(2)O4 tetrahedra,  an edgeedge with one Na(3)O4 tetrahedra,  an edgeedge with one Na(5)O4 tetrahedra, and  an edgeedge with one Na(8)O4 tetrahedra. The Na(7)-O(2) bond length is 2.29 Å. The Na(7)-O(3) bond length is 2.38 Å. The Na(7)-O(5) bond length is 2.27 Å. The Na(7)-O(6) bond length is 2.30 Å. In the eighth Na site, Na(8) is bonded to one O(1), one O(4), one O(5), and one O(6) atom to form NaO4 tetrahedra that share corners with two equivalent Na(2)O4 tetrahedra, corners with two equivalent Na(5)O4 tetrahedra, corners with three equivalent Na(3)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra,  an edgeedge with one Na(1)O4 tetrahedra,  an edgeedge with one Na(4)O4 tetrahedra, and  an edgeedge with one Na(7)O4 tetrahedra. The Na(8)-O(1) bond length is 2.31 Å. The Na(8)-O(4) bond length is 2.39 Å. The Na(8)-O(5) bond length is 2.38 Å. The Na(8)-O(6) bond length is 2.37 Å. Fe(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form FeO4 tetrahedra that share corners with two equivalent Na(1)O4 tetrahedra, corners with two equivalent Na(4)O4 tetrahedra, corners with two equivalent Na(7)O4 tetrahedra, corners with three equivalent Na(3)O4 tetrahedra, corners with three equivalent Na(8)O4 tetrahedra,  an edgeedge with one Na(2)O4 tetrahedra, and  an edgeedge with one Na(5)O4 tetrahedra. The Fe(1)-O(1) bond length is 1.79 Å. The Fe(1)-O(3) bond length is 1.86 Å. The Fe(1)-O(4) bond length is 1.78 Å. The Fe(1)-O(5) bond length is 1.79 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Na(3), one Na(8), and one Fe(1) atom to form distorted ONa4Fe trigonal bipyramids that share  a cornercorner with one O(2)Na7 pentagonal bipyramid,  a cornercorner with one O(6)Na7 pentagonal bipyramid, corners with three equivalent O(4)Na4Fe trigonal bipyramids, corners with three equivalent O(5)Na4Fe trigonal bipyramids,  an edgeedge with one O(2)Na7 pentagonal bipyramid, and  an edgeedge with one O(6)Na7 pentagonal bipyramid. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Na(5), one Na(6), and one Na(7) atom to form distorted ONa7 pentagonal bipyramids that share  a cornercorner with one O(1)Na4Fe trigonal bipyramid,  a cornercorner with one O(4)Na4Fe trigonal bipyramid,  a cornercorner with one O(5)Na4Fe trigonal bipyramid, edges with three equivalent O(6)Na7 pentagonal bipyramids,  an edgeedge with one O(1)Na4Fe trigonal bipyramid,  an edgeedge with one O(4)Na4Fe trigonal bipyramid, and  an edgeedge with one O(5)Na4Fe trigonal bipyramid. In the third O site, O(3) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(4), one Na(5), one Na(6), one Na(7), and one Fe(1) atom. In the fourth O site, O(4) is bonded to one Na(3), one Na(4), one Na(5), one Na(8), and one Fe(1) atom to form distorted ONa4Fe trigonal bipyramids that share  a cornercorner with one O(2)Na7 pentagonal bipyramid,  a cornercorner with one O(6)Na7 pentagonal bipyramid, corners with three equivalent O(1)Na4Fe trigonal bipyramids, corners with three equivalent O(5)Na4Fe trigonal bipyramids,  an edgeedge with one O(2)Na7 pentagonal bipyramid, and  an edgeedge with one O(6)Na7 pentagonal bipyramid. In the fifth O site, O(5) is bonded to one Na(3), one Na(6), one Na(7), one Na(8), and one Fe(1) atom to form distorted ONa4Fe trigonal bipyramids that share  a cornercorner with one O(2)Na7 pentagonal bipyramid,  a cornercorner with one O(6)Na7 pentagonal bipyramid, corners with three equivalent O(1)Na4Fe trigonal bipyramids, corners with three equivalent O(4)Na4Fe trigonal bipyramids,  an edgeedge with one O(2)Na7 pentagonal bipyramid, and  an edgeedge with one O(6)Na7 pentagonal bipyramid. In the sixth O site, O(6) is bonded to one Na(1), one Na(2), one Na(4), one Na(5), one Na(6), one Na(7), and one Na(8) atom to form distorted ONa7 pentagonal bipyramids that share  a cornercorner with one O(1)Na4Fe trigonal bipyramid,  a cornercorner with one O(4)Na4Fe trigonal bipyramid,  a cornercorner with one O(5)Na4Fe trigonal bipyramid, edges with three equivalent O(2)Na7 pentagonal bipyramids,  an edgeedge with one O(1)Na4Fe trigonal bipyramid,  an edgeedge with one O(4)Na4Fe trigonal bipyramid, and  an edgeedge with one O(5)Na4Fe trigonal bipyramid.