Na4Mg(BiO3)2 crystallizes in the triclinic P1 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form distorted NaO5 square pyramids that share corners with four equivalent Mg(1)O4 tetrahedra and edges with two equivalent Bi(1)O5 square pyramids. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(5), and one O(6) atom. In the third Na site, Na(3) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(6) atom. In the fourth Na site, Na(4) is bonded in a 4-coordinate geometry to one O(1), one O(3), one O(5), and one O(6) atom. Mg(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form MgO4 tetrahedra that share corners with three equivalent Bi(1)O5 square pyramids and corners with four equivalent Na(1)O5 square pyramids. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form distorted BiO5 square pyramids that share corners with three equivalent Mg(1)O4 tetrahedra and edges with two equivalent Na(1)O5 square pyramids. In the second Bi site, Bi(2) is bonded in a 3-coordinate geometry to one O(2), one O(4), and one O(6) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(4), one Mg(1), and one Bi(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(3), one Bi(1), and one Bi(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Na(1), one Na(3), one Na(4), one Mg(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(3), one Mg(1), and one Bi(2) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(4), one Mg(1), and one Bi(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal bipyramidal geometry to one Na(2), one Na(3), one Na(4), one Bi(1), and one Bi(2) atom.
Na4Mg(BiO3)2 crystallizes in the triclinic P1 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(5) atom to form distorted NaO5 square pyramids that share corners with four equivalent Mg(1)O4 tetrahedra and edges with two equivalent Bi(1)O5 square pyramids. The Na(1)-O(1) bond length is 2.53 Å. The Na(1)-O(2) bond length is 2.44 Å. The Na(1)-O(3) bond length is 2.60 Å. The Na(1)-O(4) bond length is 2.80 Å. The Na(1)-O(5) bond length is 2.53 Å. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(5), and one O(6) atom. The Na(2)-O(1) bond length is 2.59 Å. The Na(2)-O(2) bond length is 2.45 Å. The Na(2)-O(4) bond length is 2.37 Å. The Na(2)-O(5) bond length is 2.42 Å. The Na(2)-O(6) bond length is 2.36 Å. In the third Na site, Na(3) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(6) atom. The Na(3)-O(1) bond length is 2.48 Å. The Na(3)-O(2) bond length is 2.43 Å. The Na(3)-O(3) bond length is 2.49 Å. The Na(3)-O(4) bond length is 2.57 Å. The Na(3)-O(6) bond length is 2.31 Å. In the fourth Na site, Na(4) is bonded in a 4-coordinate geometry to one O(1), one O(3), one O(5), and one O(6) atom. The Na(4)-O(1) bond length is 2.37 Å. The Na(4)-O(3) bond length is 2.56 Å. The Na(4)-O(5) bond length is 2.78 Å. The Na(4)-O(6) bond length is 2.28 Å. Mg(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form MgO4 tetrahedra that share corners with three equivalent Bi(1)O5 square pyramids and corners with four equivalent Na(1)O5 square pyramids. The Mg(1)-O(1) bond length is 2.03 Å. The Mg(1)-O(3) bond length is 2.04 Å. The Mg(1)-O(4) bond length is 1.99 Å. The Mg(1)-O(5) bond length is 2.02 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form distorted BiO5 square pyramids that share corners with three equivalent Mg(1)O4 tetrahedra and edges with two equivalent Na(1)O5 square pyramids. The Bi(1)-O(1) bond length is 2.39 Å. The Bi(1)-O(2) bond length is 2.25 Å. The Bi(1)-O(3) bond length is 2.28 Å. The Bi(1)-O(5) bond length is 2.42 Å. The Bi(1)-O(6) bond length is 2.60 Å. In the second Bi site, Bi(2) is bonded in a 3-coordinate geometry to one O(2), one O(4), and one O(6) atom. The Bi(2)-O(2) bond length is 2.23 Å. The Bi(2)-O(4) bond length is 2.13 Å. The Bi(2)-O(6) bond length is 2.09 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(4), one Mg(1), and one Bi(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(3), one Bi(1), and one Bi(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Na(1), one Na(3), one Na(4), one Mg(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(3), one Mg(1), and one Bi(2) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), one Na(4), one Mg(1), and one Bi(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal bipyramidal geometry to one Na(2), one Na(3), one Na(4), one Bi(1), and one Bi(2) atom.