Na2Sb4O11 crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 3-coordinate geometry to one O(6) and two equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(4), and two equivalent O(7) atoms. There are three inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing SbO6 octahedra. The corner-sharing octahedral tilt angles range from 50-55°. In the second Sb site, Sb(2) is bonded to one O(1), one O(3), two equivalent O(4), and two equivalent O(8) atoms to form a mixture of corner and edge-sharing SbO6 octahedra. The corner-sharing octahedral tilt angles range from 48-55°. In the third Sb site, Sb(3) is bonded to one O(2), one O(4), one O(5), one O(6), and two equivalent O(7) atoms to form a mixture of corner and edge-sharing SbO6 octahedra. The corner-sharing octahedral tilt angles range from 34-48°. There are eight inequivalent O sites. In the first O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Na(2) and two equivalent Sb(3) atoms. In the second O site, O(8) is bonded in a water-like geometry to two equivalent Sb(2) atoms. In the third O site, O(1) is bonded in a trigonal planar geometry to one Sb(2) and two equivalent Sb(1) atoms. In the fourth O site, O(2) is bonded in a distorted water-like geometry to one Na(1), one Sb(1), and one Sb(3) atom. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to one Na(2), one Sb(1), and one Sb(2) atom. In the sixth O site, O(4) is bonded in a 3-coordinate geometry to one Na(2), one Sb(2), and one Sb(3) atom. In the seventh O site, O(5) is bonded in a distorted T-shaped geometry to one Sb(1) and two equivalent Sb(3) atoms. In the eighth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Na(1) and two equivalent Sb(3) atoms.
Na2Sb4O11 crystallizes in the monoclinic C2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 3-coordinate geometry to one O(6) and two equivalent O(2) atoms. The Na(1)-O(6) bond length is 2.44 Å. Both Na(1)-O(2) bond lengths are 2.92 Å. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(4), and two equivalent O(7) atoms. The Na(2)-O(3) bond length is 2.62 Å. Both Na(2)-O(4) bond lengths are 2.70 Å. Both Na(2)-O(7) bond lengths are 2.47 Å. There are three inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing SbO6 octahedra. The corner-sharing octahedral tilt angles range from 50-55°. The Sb(1)-O(3) bond length is 1.95 Å. The Sb(1)-O(5) bond length is 2.03 Å. There is one shorter (2.01 Å) and one longer (2.16 Å) Sb(1)-O(1) bond length. Both Sb(1)-O(2) bond lengths are 2.01 Å. In the second Sb site, Sb(2) is bonded to one O(1), one O(3), two equivalent O(4), and two equivalent O(8) atoms to form a mixture of corner and edge-sharing SbO6 octahedra. The corner-sharing octahedral tilt angles range from 48-55°. The Sb(2)-O(1) bond length is 2.11 Å. The Sb(2)-O(3) bond length is 1.99 Å. Both Sb(2)-O(4) bond lengths are 1.97 Å. Both Sb(2)-O(8) bond lengths are 2.02 Å. In the third Sb site, Sb(3) is bonded to one O(2), one O(4), one O(5), one O(6), and two equivalent O(7) atoms to form a mixture of corner and edge-sharing SbO6 octahedra. The corner-sharing octahedral tilt angles range from 34-48°. The Sb(3)-O(2) bond length is 2.04 Å. The Sb(3)-O(4) bond length is 2.00 Å. The Sb(3)-O(5) bond length is 2.06 Å. The Sb(3)-O(6) bond length is 1.97 Å. There is one shorter (2.01 Å) and one longer (2.02 Å) Sb(3)-O(7) bond length. There are eight inequivalent O sites. In the first O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Na(2) and two equivalent Sb(3) atoms. In the second O site, O(8) is bonded in a water-like geometry to two equivalent Sb(2) atoms. In the third O site, O(1) is bonded in a trigonal planar geometry to one Sb(2) and two equivalent Sb(1) atoms. In the fourth O site, O(2) is bonded in a distorted water-like geometry to one Na(1), one Sb(1), and one Sb(3) atom. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to one Na(2), one Sb(1), and one Sb(2) atom. In the sixth O site, O(4) is bonded in a 3-coordinate geometry to one Na(2), one Sb(2), and one Sb(3) atom. In the seventh O site, O(5) is bonded in a distorted T-shaped geometry to one Sb(1) and two equivalent Sb(3) atoms. In the eighth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Na(1) and two equivalent Sb(3) atoms.