MgMnO2 is Caswellsilverite-like structured and crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), two equivalent O(3), and three equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with three equivalent Mg(2)O6 octahedra, edges with three equivalent Mn(1)O6 octahedra, and edges with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the second Mg site, Mg(2) is bonded to one O(3), two equivalent O(4), and three equivalent O(2) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, edges with three equivalent Mn(2)O6 octahedra, and edges with four equivalent Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-4°. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(2), two equivalent O(1), and three equivalent O(3) atoms to form MnO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, edges with three equivalent Mn(2)O6 octahedra, and edges with four equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-4°. In the second Mn site, Mn(2) is bonded to one O(4), two equivalent O(2), and three equivalent O(1) atoms to form MnO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with three equivalent Mg(2)O6 octahedra, edges with three equivalent Mn(1)O6 octahedra, and edges with four equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), two equivalent Mn(1), and three equivalent Mn(2) atoms to form OMgMn5 octahedra that share corners with two equivalent O(2)Mg3Mn3 octahedra, corners with two equivalent O(3)Mg3Mn3 octahedra, corners with two equivalent O(4)Mg5Mn octahedra, edges with two equivalent O(4)Mg5Mn octahedra, edges with three equivalent O(2)Mg3Mn3 octahedra, edges with three equivalent O(3)Mg3Mn3 octahedra, and edges with four equivalent O(1)MgMn5 octahedra. The corner-sharing octahedral tilt angles range from 1-2°. In the second O site, O(2) is bonded to three equivalent Mg(2), one Mn(1), and two equivalent Mn(2) atoms to form OMg3Mn3 octahedra that share corners with two equivalent O(3)Mg3Mn3 octahedra, corners with two equivalent O(4)Mg5Mn octahedra, corners with two equivalent O(1)MgMn5 octahedra, edges with two equivalent O(3)Mg3Mn3 octahedra, edges with three equivalent O(4)Mg5Mn octahedra, edges with three equivalent O(1)MgMn5 octahedra, and edges with four equivalent O(2)Mg3Mn3 octahedra. The corner-sharing octahedral tilt angles are 1°. In the third O site, O(3) is bonded to one Mg(2), two equivalent Mg(1), and three equivalent Mn(1) atoms to form OMg3Mn3 octahedra that share corners with two equivalent O(2)Mg3Mn3 octahedra, corners with two equivalent O(4)Mg5Mn octahedra, corners with two equivalent O(1)MgMn5 octahedra, edges with two equivalent O(2)Mg3Mn3 octahedra, edges with three equivalent O(4)Mg5Mn octahedra, edges with three equivalent O(1)MgMn5 octahedra, and edges with four equivalent O(3)Mg3Mn3 octahedra. The corner-sharing octahedral tilt angles range from 1-2°. In the fourth O site, O(4) is bonded to two equivalent Mg(2), three equivalent Mg(1), and one Mn(2) atom to form OMg5Mn octahedra that share corners with two equivalent O(2)Mg3Mn3 octahedra, corners with two equivalent O(3)Mg3Mn3 octahedra, corners with two equivalent O(1)MgMn5 octahedra, edges with two equivalent O(1)MgMn5 octahedra, edges with three equivalent O(2)Mg3Mn3 octahedra, edges with three equivalent O(3)Mg3Mn3 octahedra, and edges with four equivalent O(4)Mg5Mn octahedra. The corner-sharing octahedral tilt angles range from 1-2°.
MgMnO2 is Caswellsilverite-like structured and crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), two equivalent O(3), and three equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with three equivalent Mg(2)O6 octahedra, edges with three equivalent Mn(1)O6 octahedra, and edges with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. The Mg(1)-O(1) bond length is 2.15 Å. Both Mg(1)-O(3) bond lengths are 2.15 Å. There is one shorter (2.12 Å) and two longer (2.18 Å) Mg(1)-O(4) bond lengths. In the second Mg site, Mg(2) is bonded to one O(3), two equivalent O(4), and three equivalent O(2) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, edges with three equivalent Mn(2)O6 octahedra, and edges with four equivalent Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-4°. The Mg(2)-O(3) bond length is 2.13 Å. Both Mg(2)-O(4) bond lengths are 2.18 Å. There are two shorter (2.15 Å) and one longer (2.16 Å) Mg(2)-O(2) bond length. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(2), two equivalent O(1), and three equivalent O(3) atoms to form MnO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, edges with three equivalent Mn(2)O6 octahedra, and edges with four equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-4°. The Mn(1)-O(2) bond length is 2.25 Å. Both Mn(1)-O(1) bond lengths are 2.21 Å. All Mn(1)-O(3) bond lengths are 2.24 Å. In the second Mn site, Mn(2) is bonded to one O(4), two equivalent O(2), and three equivalent O(1) atoms to form MnO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with three equivalent Mg(2)O6 octahedra, edges with three equivalent Mn(1)O6 octahedra, and edges with four equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. The Mn(2)-O(4) bond length is 2.22 Å. Both Mn(2)-O(2) bond lengths are 2.22 Å. There are two shorter (2.21 Å) and one longer (2.30 Å) Mn(2)-O(1) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), two equivalent Mn(1), and three equivalent Mn(2) atoms to form OMgMn5 octahedra that share corners with two equivalent O(2)Mg3Mn3 octahedra, corners with two equivalent O(3)Mg3Mn3 octahedra, corners with two equivalent O(4)Mg5Mn octahedra, edges with two equivalent O(4)Mg5Mn octahedra, edges with three equivalent O(2)Mg3Mn3 octahedra, edges with three equivalent O(3)Mg3Mn3 octahedra, and edges with four equivalent O(1)MgMn5 octahedra. The corner-sharing octahedral tilt angles range from 1-2°. In the second O site, O(2) is bonded to three equivalent Mg(2), one Mn(1), and two equivalent Mn(2) atoms to form OMg3Mn3 octahedra that share corners with two equivalent O(3)Mg3Mn3 octahedra, corners with two equivalent O(4)Mg5Mn octahedra, corners with two equivalent O(1)MgMn5 octahedra, edges with two equivalent O(3)Mg3Mn3 octahedra, edges with three equivalent O(4)Mg5Mn octahedra, edges with three equivalent O(1)MgMn5 octahedra, and edges with four equivalent O(2)Mg3Mn3 octahedra. The corner-sharing octahedral tilt angles are 1°. In the third O site, O(3) is bonded to one Mg(2), two equivalent Mg(1), and three equivalent Mn(1) atoms to form OMg3Mn3 octahedra that share corners with two equivalent O(2)Mg3Mn3 octahedra, corners with two equivalent O(4)Mg5Mn octahedra, corners with two equivalent O(1)MgMn5 octahedra, edges with two equivalent O(2)Mg3Mn3 octahedra, edges with three equivalent O(4)Mg5Mn octahedra, edges with three equivalent O(1)MgMn5 octahedra, and edges with four equivalent O(3)Mg3Mn3 octahedra. The corner-sharing octahedral tilt angles range from 1-2°. In the fourth O site, O(4) is bonded to two equivalent Mg(2), three equivalent Mg(1), and one Mn(2) atom to form OMg5Mn octahedra that share corners with two equivalent O(2)Mg3Mn3 octahedra, corners with two equivalent O(3)Mg3Mn3 octahedra, corners with two equivalent O(1)MgMn5 octahedra, edges with two equivalent O(1)MgMn5 octahedra, edges with three equivalent O(2)Mg3Mn3 octahedra, edges with three equivalent O(3)Mg3Mn3 octahedra, and edges with four equivalent O(4)Mg5Mn octahedra. The corner-sharing octahedral tilt angles range from 1-2°.