Na2MgMn2O4 crystallizes in the monoclinic Pm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(1), and two equivalent O(3) atoms. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(2), and two equivalent O(4) atoms. Mg(1) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form MgO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra and corners with four equivalent Mn(2)O5 trigonal bipyramids. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(1), and two equivalent O(3) atoms. In the second Mn site, Mn(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted MnO5 trigonal bipyramids that share corners with four equivalent Mg(1)O4 tetrahedra and edges with two equivalent Mn(2)O5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), one Mn(2), and two equivalent Mn(1) atoms to form distorted ONa2Mn3 trigonal bipyramids that share corners with four equivalent O(2)Na2MgMn3 octahedra and edges with two equivalent O(1)Na2Mn3 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 67-77°. In the second O site, O(2) is bonded to two equivalent Na(2), one Mg(1), one Mn(1), and two equivalent Mn(2) atoms to form distorted ONa2MgMn3 octahedra that share corners with four equivalent O(1)Na2Mn3 trigonal bipyramids and edges with two equivalent O(2)Na2MgMn3 octahedra. In the third O site, O(3) is bonded in a 7-coordinate geometry to one Na(2), two equivalent Na(1), two equivalent Mg(1), and two equivalent Mn(1) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Na(1), two equivalent Na(2), one Mg(1), and two equivalent Mn(2) atoms.
Na2MgMn2O4 crystallizes in the monoclinic Pm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(1), and two equivalent O(3) atoms. The Na(1)-O(4) bond length is 2.55 Å. Both Na(1)-O(1) bond lengths are 2.26 Å. Both Na(1)-O(3) bond lengths are 2.57 Å. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(2), and two equivalent O(4) atoms. The Na(2)-O(3) bond length is 2.24 Å. Both Na(2)-O(2) bond lengths are 2.47 Å. Both Na(2)-O(4) bond lengths are 2.36 Å. Mg(1) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form MgO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra and corners with four equivalent Mn(2)O5 trigonal bipyramids. The Mg(1)-O(2) bond length is 2.03 Å. The Mg(1)-O(4) bond length is 2.03 Å. Both Mg(1)-O(3) bond lengths are 2.01 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(1), and two equivalent O(3) atoms. The Mn(1)-O(2) bond length is 2.13 Å. Both Mn(1)-O(1) bond lengths are 2.08 Å. Both Mn(1)-O(3) bond lengths are 2.50 Å. In the second Mn site, Mn(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted MnO5 trigonal bipyramids that share corners with four equivalent Mg(1)O4 tetrahedra and edges with two equivalent Mn(2)O5 trigonal bipyramids. The Mn(2)-O(1) bond length is 2.17 Å. Both Mn(2)-O(2) bond lengths are 2.36 Å. Both Mn(2)-O(4) bond lengths are 2.24 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), one Mn(2), and two equivalent Mn(1) atoms to form distorted ONa2Mn3 trigonal bipyramids that share corners with four equivalent O(2)Na2MgMn3 octahedra and edges with two equivalent O(1)Na2Mn3 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 67-77°. In the second O site, O(2) is bonded to two equivalent Na(2), one Mg(1), one Mn(1), and two equivalent Mn(2) atoms to form distorted ONa2MgMn3 octahedra that share corners with four equivalent O(1)Na2Mn3 trigonal bipyramids and edges with two equivalent O(2)Na2MgMn3 octahedra. In the third O site, O(3) is bonded in a 7-coordinate geometry to one Na(2), two equivalent Na(1), two equivalent Mg(1), and two equivalent Mn(1) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to one Na(1), two equivalent Na(2), one Mg(1), and two equivalent Mn(2) atoms.