NaMnO2 crystallizes in the monoclinic Pm space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(6) atoms to form distorted NaO6 octahedra that share corners with four equivalent Na(4)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids, corners with two equivalent Mn(2)O5 square pyramids, corners with two equivalent Mn(4)O5 square pyramids, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Mn(4)O5 square pyramids,  a faceface with one Mn(1)O5 square pyramid, and  a faceface with one Mn(2)O5 square pyramid. The corner-sharing octahedral tilt angles range from 45-49°. In the second Na site, Na(2) is bonded to one O(2), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form distorted NaO6 octahedra that share corners with three equivalent Na(4)O6 octahedra, corners with four equivalent Mn(3)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids, corners with two equivalent Mn(2)O5 square pyramids,  an edgeedge with one Na(4)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, and faces with two equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-48°. In the third Na site, Na(3) is bonded in a 6-coordinate geometry to one O(1), one O(5), two equivalent O(3), and two equivalent O(7) atoms. In the fourth Na site, Na(4) is bonded to one O(2), one O(6), two equivalent O(4), and two equivalent O(8) atoms to form distorted NaO6 octahedra that share corners with two equivalent Mn(3)O6 octahedra, corners with three equivalent Na(2)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, corners with two equivalent Mn(2)O5 square pyramids, corners with two equivalent Mn(4)O5 square pyramids,  an edgeedge with one Na(2)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, edges with two equivalent Mn(2)O5 square pyramids,  a faceface with one Mn(3)O6 octahedra, and  a faceface with one Mn(4)O5 square pyramid. The corner-sharing octahedral tilt angles range from 39-49°. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(7), two equivalent O(1), and two equivalent O(5) atoms to form distorted MnO5 square pyramids that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Mn(4)O5 square pyramids, edges with two equivalent Mn(1)O5 square pyramids, and  a faceface with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-79°. In the second Mn site, Mn(2) is bonded to one O(4), two equivalent O(2), and two equivalent O(6) atoms to form distorted MnO5 square pyramids that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Na(4)O6 octahedra, corners with two equivalent Mn(3)O6 octahedra, corners with four equivalent Mn(4)O5 square pyramids, edges with two equivalent Na(4)O6 octahedra, edges with two equivalent Mn(2)O5 square pyramids, and  a faceface with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-86°. In the third Mn site, Mn(3) is bonded to one O(2), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form distorted MnO6 octahedra that share corners with two equivalent Na(4)O6 octahedra, corners with four equivalent Na(2)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids, corners with two equivalent Mn(2)O5 square pyramids, edges with two equivalent Mn(3)O6 octahedra,  a faceface with one Na(4)O6 octahedra, and faces with two equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-48°. In the fourth Mn site, Mn(4) is bonded to one O(6), two equivalent O(4), and two equivalent O(7) atoms to form distorted MnO5 square pyramids that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(4)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids, corners with four equivalent Mn(2)O5 square pyramids, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Mn(4)O5 square pyramids, and  a faceface with one Na(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-84°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Na(3), two equivalent Na(1), and two equivalent Mn(1) atoms to form distorted ONa3Mn2 trigonal bipyramids that share corners with three equivalent O(5)Na2Mn3 trigonal bipyramids,  an edgeedge with one O(5)Na2Mn3 trigonal bipyramid, and edges with two equivalent O(1)Na3Mn2 trigonal bipyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(2), one Na(4), one Mn(3), and two equivalent Mn(2) atoms. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Na(2), two equivalent Na(3), and two equivalent Mn(3) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Na(1), two equivalent Na(4), one Mn(2), and two equivalent Mn(4) atoms. In the fifth O site, O(5) is bonded to one Na(2), one Na(3), one Mn(3), and two equivalent Mn(1) atoms to form distorted ONa2Mn3 trigonal bipyramids that share corners with two equivalent O(5)Na2Mn3 trigonal bipyramids, corners with three equivalent O(1)Na3Mn2 trigonal bipyramids, and  an edgeedge with one O(1)Na3Mn2 trigonal bipyramid. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to one Na(4), two equivalent Na(1), one Mn(4), and two equivalent Mn(2) atoms. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one Na(1), two equivalent Na(3), one Mn(1), and two equivalent Mn(4) atoms. In the eighth O site, O(8) is bonded in a 6-coordinate geometry to two equivalent Na(2), two equivalent Na(4), and two equivalent Mn(3) atoms.
NaMnO2 crystallizes in the monoclinic Pm space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(6) atoms to form distorted NaO6 octahedra that share corners with four equivalent Na(4)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids, corners with two equivalent Mn(2)O5 square pyramids, corners with two equivalent Mn(4)O5 square pyramids, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Mn(4)O5 square pyramids,  a faceface with one Mn(1)O5 square pyramid, and  a faceface with one Mn(2)O5 square pyramid. The corner-sharing octahedral tilt angles range from 45-49°. The Na(1)-O(4) bond length is 2.43 Å. The Na(1)-O(7) bond length is 2.50 Å. Both Na(1)-O(1) bond lengths are 2.31 Å. Both Na(1)-O(6) bond lengths are 2.43 Å. In the second Na site, Na(2) is bonded to one O(2), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form distorted NaO6 octahedra that share corners with three equivalent Na(4)O6 octahedra, corners with four equivalent Mn(3)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids, corners with two equivalent Mn(2)O5 square pyramids,  an edgeedge with one Na(4)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, and faces with two equivalent Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-48°. The Na(2)-O(2) bond length is 2.36 Å. The Na(2)-O(5) bond length is 2.42 Å. Both Na(2)-O(3) bond lengths are 2.48 Å. Both Na(2)-O(8) bond lengths are 2.51 Å. In the third Na site, Na(3) is bonded in a 6-coordinate geometry to one O(1), one O(5), two equivalent O(3), and two equivalent O(7) atoms. The Na(3)-O(1) bond length is 2.26 Å. The Na(3)-O(5) bond length is 2.33 Å. Both Na(3)-O(3) bond lengths are 2.49 Å. Both Na(3)-O(7) bond lengths are 2.61 Å. In the fourth Na site, Na(4) is bonded to one O(2), one O(6), two equivalent O(4), and two equivalent O(8) atoms to form distorted NaO6 octahedra that share corners with two equivalent Mn(3)O6 octahedra, corners with three equivalent Na(2)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, corners with two equivalent Mn(2)O5 square pyramids, corners with two equivalent Mn(4)O5 square pyramids,  an edgeedge with one Na(2)O6 octahedra, edges with two equivalent Na(4)O6 octahedra, edges with two equivalent Mn(2)O5 square pyramids,  a faceface with one Mn(3)O6 octahedra, and  a faceface with one Mn(4)O5 square pyramid. The corner-sharing octahedral tilt angles range from 39-49°. The Na(4)-O(2) bond length is 2.35 Å. The Na(4)-O(6) bond length is 2.48 Å. Both Na(4)-O(4) bond lengths are 2.49 Å. Both Na(4)-O(8) bond lengths are 2.41 Å. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(7), two equivalent O(1), and two equivalent O(5) atoms to form distorted MnO5 square pyramids that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Mn(4)O5 square pyramids, edges with two equivalent Mn(1)O5 square pyramids, and  a faceface with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 41-79°. The Mn(1)-O(7) bond length is 2.41 Å. Both Mn(1)-O(1) bond lengths are 1.95 Å. Both Mn(1)-O(5) bond lengths are 1.93 Å. In the second Mn site, Mn(2) is bonded to one O(4), two equivalent O(2), and two equivalent O(6) atoms to form distorted MnO5 square pyramids that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Na(4)O6 octahedra, corners with two equivalent Mn(3)O6 octahedra, corners with four equivalent Mn(4)O5 square pyramids, edges with two equivalent Na(4)O6 octahedra, edges with two equivalent Mn(2)O5 square pyramids, and  a faceface with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-86°. The Mn(2)-O(4) bond length is 2.58 Å. Both Mn(2)-O(2) bond lengths are 1.92 Å. Both Mn(2)-O(6) bond lengths are 1.98 Å. In the third Mn site, Mn(3) is bonded to one O(2), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form distorted MnO6 octahedra that share corners with two equivalent Na(4)O6 octahedra, corners with four equivalent Na(2)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids, corners with two equivalent Mn(2)O5 square pyramids, edges with two equivalent Mn(3)O6 octahedra,  a faceface with one Na(4)O6 octahedra, and faces with two equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-48°. The Mn(3)-O(2) bond length is 2.63 Å. The Mn(3)-O(5) bond length is 2.28 Å. Both Mn(3)-O(3) bond lengths are 1.97 Å. Both Mn(3)-O(8) bond lengths are 1.98 Å. In the fourth Mn site, Mn(4) is bonded to one O(6), two equivalent O(4), and two equivalent O(7) atoms to form distorted MnO5 square pyramids that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(4)O6 octahedra, corners with two equivalent Mn(1)O5 square pyramids, corners with four equivalent Mn(2)O5 square pyramids, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Mn(4)O5 square pyramids, and  a faceface with one Na(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-84°. The Mn(4)-O(6) bond length is 2.47 Å. Both Mn(4)-O(4) bond lengths are 1.96 Å. Both Mn(4)-O(7) bond lengths are 1.96 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Na(3), two equivalent Na(1), and two equivalent Mn(1) atoms to form distorted ONa3Mn2 trigonal bipyramids that share corners with three equivalent O(5)Na2Mn3 trigonal bipyramids,  an edgeedge with one O(5)Na2Mn3 trigonal bipyramid, and edges with two equivalent O(1)Na3Mn2 trigonal bipyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(2), one Na(4), one Mn(3), and two equivalent Mn(2) atoms. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Na(2), two equivalent Na(3), and two equivalent Mn(3) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Na(1), two equivalent Na(4), one Mn(2), and two equivalent Mn(4) atoms. In the fifth O site, O(5) is bonded to one Na(2), one Na(3), one Mn(3), and two equivalent Mn(1) atoms to form distorted ONa2Mn3 trigonal bipyramids that share corners with two equivalent O(5)Na2Mn3 trigonal bipyramids, corners with three equivalent O(1)Na3Mn2 trigonal bipyramids, and  an edgeedge with one O(1)Na3Mn2 trigonal bipyramid. In the sixth O site, O(6) is bonded in a 6-coordinate geometry to one Na(4), two equivalent Na(1), one Mn(4), and two equivalent Mn(2) atoms. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one Na(1), two equivalent Na(3), one Mn(1), and two equivalent Mn(4) atoms. In the eighth O site, O(8) is bonded in a 6-coordinate geometry to two equivalent Na(2), two equivalent Na(4), and two equivalent Mn(3) atoms.