NaMn2O4 crystallizes in the orthorhombic Cmcm space group. Na(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), and four equivalent O(1) atoms. Mn(1) is bonded to one O(2), two equivalent O(3), and three equivalent O(1) atoms to form a mixture of edge and corner-sharing MnO6 octahedra. The corner-sharing octahedral tilt angles range from 0-44°. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1) and three equivalent Mn(1) atoms to form distorted ONa2Mn3 trigonal bipyramids that share corners with four equivalent O(3)Na2Mn4 octahedra, corners with five equivalent O(2)Na2Mn2 tetrahedra, corners with two equivalent O(1)Na2Mn3 trigonal bipyramids, edges with three equivalent O(3)Na2Mn4 octahedra,  an edgeedge with one O(2)Na2Mn2 tetrahedra, and edges with five equivalent O(1)Na2Mn3 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 10-42°. In the second O site, O(2) is bonded to two equivalent Na(1) and two equivalent Mn(1) atoms to form distorted ONa2Mn2 tetrahedra that share corners with two equivalent O(2)Na2Mn2 tetrahedra, corners with ten equivalent O(1)Na2Mn3 trigonal bipyramids, edges with four equivalent O(3)Na2Mn4 octahedra, and edges with two equivalent O(1)Na2Mn3 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Na(1) and four equivalent Mn(1) atoms to form ONa2Mn4 octahedra that share corners with two equivalent O(3)Na2Mn4 octahedra, corners with eight equivalent O(1)Na2Mn3 trigonal bipyramids, edges with two equivalent O(3)Na2Mn4 octahedra, edges with four equivalent O(2)Na2Mn2 tetrahedra, and edges with six equivalent O(1)Na2Mn3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 46°.
NaMn2O4 crystallizes in the orthorhombic Cmcm space group. Na(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), and four equivalent O(1) atoms. Both Na(1)-O(2) bond lengths are 2.27 Å. Both Na(1)-O(3) bond lengths are 2.67 Å. All Na(1)-O(1) bond lengths are 2.44 Å. Mn(1) is bonded to one O(2), two equivalent O(3), and three equivalent O(1) atoms to form a mixture of edge and corner-sharing MnO6 octahedra. The corner-sharing octahedral tilt angles range from 0-44°. The Mn(1)-O(2) bond length is 1.88 Å. Both Mn(1)-O(3) bond lengths are 2.15 Å. There is one shorter (1.98 Å) and two longer (2.00 Å) Mn(1)-O(1) bond lengths. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1) and three equivalent Mn(1) atoms to form distorted ONa2Mn3 trigonal bipyramids that share corners with four equivalent O(3)Na2Mn4 octahedra, corners with five equivalent O(2)Na2Mn2 tetrahedra, corners with two equivalent O(1)Na2Mn3 trigonal bipyramids, edges with three equivalent O(3)Na2Mn4 octahedra,  an edgeedge with one O(2)Na2Mn2 tetrahedra, and edges with five equivalent O(1)Na2Mn3 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 10-42°. In the second O site, O(2) is bonded to two equivalent Na(1) and two equivalent Mn(1) atoms to form distorted ONa2Mn2 tetrahedra that share corners with two equivalent O(2)Na2Mn2 tetrahedra, corners with ten equivalent O(1)Na2Mn3 trigonal bipyramids, edges with four equivalent O(3)Na2Mn4 octahedra, and edges with two equivalent O(1)Na2Mn3 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Na(1) and four equivalent Mn(1) atoms to form ONa2Mn4 octahedra that share corners with two equivalent O(3)Na2Mn4 octahedra, corners with eight equivalent O(1)Na2Mn3 trigonal bipyramids, edges with two equivalent O(3)Na2Mn4 octahedra, edges with four equivalent O(2)Na2Mn2 tetrahedra, and edges with six equivalent O(1)Na2Mn3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 46°.