Na2Mg(BiO3)2 crystallizes in the trigonal R3 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted NaO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, edges with three equivalent Bi(2)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 54°. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MgO6 octahedra that share corners with three equivalent Na(1)O6 octahedra, corners with six equivalent Bi(2)O6 octahedra, and  a faceface with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-54°. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. In the second Bi site, Bi(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form BiO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra and edges with three equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-37°. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Mg(1), one Bi(1), and one Bi(2) atom to form a mixture of distorted corner and edge-sharing ONa2MgBi2 trigonal bipyramids. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Mg(1), one Bi(1), and one Bi(2) atom to form a mixture of distorted corner and edge-sharing ONa2MgBi2 trigonal bipyramids.
Na2Mg(BiO3)2 crystallizes in the trigonal R3 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted NaO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, edges with three equivalent Bi(2)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 54°. All Na(1)-O(1) bond lengths are 2.26 Å. All Na(1)-O(2) bond lengths are 2.44 Å. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. All Na(2)-O(1) bond lengths are 2.30 Å. All Na(2)-O(2) bond lengths are 2.58 Å. Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MgO6 octahedra that share corners with three equivalent Na(1)O6 octahedra, corners with six equivalent Bi(2)O6 octahedra, and  a faceface with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-54°. All Mg(1)-O(1) bond lengths are 2.25 Å. All Mg(1)-O(2) bond lengths are 2.19 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. All Bi(1)-O(1) bond lengths are 2.38 Å. All Bi(1)-O(2) bond lengths are 2.43 Å. In the second Bi site, Bi(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form BiO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra and edges with three equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-37°. All Bi(2)-O(1) bond lengths are 2.22 Å. All Bi(2)-O(2) bond lengths are 2.16 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Mg(1), one Bi(1), and one Bi(2) atom to form a mixture of distorted corner and edge-sharing ONa2MgBi2 trigonal bipyramids. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Mg(1), one Bi(1), and one Bi(2) atom to form a mixture of distorted corner and edge-sharing ONa2MgBi2 trigonal bipyramids.