Na5MnO5 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted NaO4 trigonal pyramids that share corners with two equivalent Na(3)O5 square pyramids, corners with two equivalent Mn(1)O5 trigonal bipyramids, corners with four equivalent Na(2)O5 trigonal bipyramids,  a cornercorner with one Na(1)O4 trigonal pyramid,  an edgeedge with one Na(3)O5 square pyramid,  an edgeedge with one Mn(1)O5 trigonal bipyramid, edges with two equivalent Na(2)O5 trigonal bipyramids, and  an edgeedge with one Na(1)O4 trigonal pyramid. In the second Na site, Na(2) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted NaO5 trigonal bipyramids that share  a cornercorner with one Na(3)O5 square pyramid,  a cornercorner with one Na(2)O5 trigonal bipyramid, corners with three equivalent Mn(1)O5 trigonal bipyramids, corners with four equivalent Na(1)O4 trigonal pyramids, edges with two equivalent Na(3)O5 square pyramids,  an edgeedge with one Mn(1)O5 trigonal bipyramid, edges with two equivalent Na(2)O5 trigonal bipyramids, and edges with two equivalent Na(1)O4 trigonal pyramids. In the third Na site, Na(3) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted NaO5 square pyramids that share  a cornercorner with one Mn(1)O5 trigonal bipyramid, corners with two equivalent Na(2)O5 trigonal bipyramids, corners with four equivalent Na(1)O4 trigonal pyramids, edges with two equivalent Mn(1)O5 trigonal bipyramids, edges with four equivalent Na(2)O5 trigonal bipyramids, and edges with two equivalent Na(1)O4 trigonal pyramids. Mn(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form MnO5 trigonal bipyramids that share  a cornercorner with one Na(3)O5 square pyramid, corners with six equivalent Na(2)O5 trigonal bipyramids, corners with four equivalent Na(1)O4 trigonal pyramids, edges with two equivalent Na(3)O5 square pyramids, edges with two equivalent Na(2)O5 trigonal bipyramids, and edges with two equivalent Na(1)O4 trigonal pyramids. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), one Na(3), two equivalent Na(2), and one Mn(1) atom. In the second O site, O(2) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Mn(1) atom to form a mixture of distorted edge and corner-sharing ONa5Mn octahedra. The corner-sharing octahedral tilt angles range from 6-29°. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Mn(1) atom.
Na5MnO5 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted NaO4 trigonal pyramids that share corners with two equivalent Na(3)O5 square pyramids, corners with two equivalent Mn(1)O5 trigonal bipyramids, corners with four equivalent Na(2)O5 trigonal bipyramids,  a cornercorner with one Na(1)O4 trigonal pyramid,  an edgeedge with one Na(3)O5 square pyramid,  an edgeedge with one Mn(1)O5 trigonal bipyramid, edges with two equivalent Na(2)O5 trigonal bipyramids, and  an edgeedge with one Na(1)O4 trigonal pyramid. The Na(1)-O(1) bond length is 2.34 Å. The Na(1)-O(3) bond length is 2.38 Å. There is one shorter (2.26 Å) and one longer (2.44 Å) Na(1)-O(2) bond length. In the second Na site, Na(2) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted NaO5 trigonal bipyramids that share  a cornercorner with one Na(3)O5 square pyramid,  a cornercorner with one Na(2)O5 trigonal bipyramid, corners with three equivalent Mn(1)O5 trigonal bipyramids, corners with four equivalent Na(1)O4 trigonal pyramids, edges with two equivalent Na(3)O5 square pyramids,  an edgeedge with one Mn(1)O5 trigonal bipyramid, edges with two equivalent Na(2)O5 trigonal bipyramids, and edges with two equivalent Na(1)O4 trigonal pyramids. The Na(2)-O(3) bond length is 2.40 Å. There is one shorter (2.36 Å) and one longer (2.60 Å) Na(2)-O(1) bond length. There is one shorter (2.25 Å) and one longer (2.43 Å) Na(2)-O(2) bond length. In the third Na site, Na(3) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted NaO5 square pyramids that share  a cornercorner with one Mn(1)O5 trigonal bipyramid, corners with two equivalent Na(2)O5 trigonal bipyramids, corners with four equivalent Na(1)O4 trigonal pyramids, edges with two equivalent Mn(1)O5 trigonal bipyramids, edges with four equivalent Na(2)O5 trigonal bipyramids, and edges with two equivalent Na(1)O4 trigonal pyramids. The Na(3)-O(3) bond length is 2.61 Å. Both Na(3)-O(1) bond lengths are 2.33 Å. Both Na(3)-O(2) bond lengths are 2.24 Å. Mn(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form MnO5 trigonal bipyramids that share  a cornercorner with one Na(3)O5 square pyramid, corners with six equivalent Na(2)O5 trigonal bipyramids, corners with four equivalent Na(1)O4 trigonal pyramids, edges with two equivalent Na(3)O5 square pyramids, edges with two equivalent Na(2)O5 trigonal bipyramids, and edges with two equivalent Na(1)O4 trigonal pyramids. The Mn(1)-O(3) bond length is 1.78 Å. Both Mn(1)-O(1) bond lengths are 1.79 Å. Both Mn(1)-O(2) bond lengths are 1.98 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), one Na(3), two equivalent Na(2), and one Mn(1) atom. In the second O site, O(2) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Mn(1) atom to form a mixture of distorted edge and corner-sharing ONa5Mn octahedra. The corner-sharing octahedral tilt angles range from 6-29°. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Mn(1) atom.