Na3Sb3(PO7)2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(3), one O(5), one O(6), one O(7), and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form NaO8 hexagonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra, edges with two equivalent Sb(2)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to one O(1), one O(3), one O(6), one O(7), and two equivalent O(2) atoms to form SbO6 octahedra that share corners with two equivalent Sb(1)O6 octahedra, corners with two equivalent Sb(2)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, and edges with two equivalent Na(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 41-52°. In the second Sb site, Sb(2) is bonded to two equivalent O(1), two equivalent O(5), and two equivalent O(6) atoms to form SbO6 octahedra that share corners with four equivalent Sb(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, and edges with two equivalent Na(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 41-52°. P(1) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Na(2)O8 hexagonal bipyramid,  a cornercorner with one Sb(2)O6 octahedra, and corners with two equivalent Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-53°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to one Na(1), one Sb(2), and one P(1) atom. In the second O site, O(6) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Sb(1), and one Sb(2) atom. In the third O site, O(7) is bonded in a 2-coordinate geometry to one Na(1), one Sb(1), and one P(1) atom. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one Na(2), one Sb(1), and one Sb(2) atom. In the fifth O site, O(2) is bonded in a 3-coordinate geometry to one Na(2) and two equivalent Sb(1) atoms. In the sixth O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Sb(1), and one P(1) atom. In the seventh O site, O(4) is bonded to one Na(2), two equivalent Na(1), and one P(1) atom to form a mixture of distorted corner and edge-sharing ONa3P tetrahedra.
Na3Sb3(PO7)2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(3), one O(5), one O(6), one O(7), and two equivalent O(4) atoms. The Na(1)-O(3) bond length is 2.29 Å. The Na(1)-O(5) bond length is 2.80 Å. The Na(1)-O(6) bond length is 2.55 Å. The Na(1)-O(7) bond length is 2.81 Å. Both Na(1)-O(4) bond lengths are 2.33 Å. In the second Na site, Na(2) is bonded to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(6) atoms to form NaO8 hexagonal bipyramids that share corners with two equivalent P(1)O4 tetrahedra, edges with two equivalent Sb(2)O6 octahedra, and edges with four equivalent Sb(1)O6 octahedra. Both Na(2)-O(1) bond lengths are 2.52 Å. Both Na(2)-O(2) bond lengths are 2.60 Å. Both Na(2)-O(4) bond lengths are 2.48 Å. Both Na(2)-O(6) bond lengths are 2.65 Å. There are two inequivalent Sb sites. In the first Sb site, Sb(1) is bonded to one O(1), one O(3), one O(6), one O(7), and two equivalent O(2) atoms to form SbO6 octahedra that share corners with two equivalent Sb(1)O6 octahedra, corners with two equivalent Sb(2)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, and edges with two equivalent Na(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 41-52°. The Sb(1)-O(1) bond length is 1.95 Å. The Sb(1)-O(3) bond length is 2.02 Å. The Sb(1)-O(6) bond length is 1.98 Å. The Sb(1)-O(7) bond length is 2.00 Å. There is one shorter (1.93 Å) and one longer (1.95 Å) Sb(1)-O(2) bond length. In the second Sb site, Sb(2) is bonded to two equivalent O(1), two equivalent O(5), and two equivalent O(6) atoms to form SbO6 octahedra that share corners with four equivalent Sb(1)O6 octahedra, corners with two equivalent P(1)O4 tetrahedra, and edges with two equivalent Na(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 41-52°. Both Sb(2)-O(1) bond lengths are 1.94 Å. Both Sb(2)-O(5) bond lengths are 2.04 Å. Both Sb(2)-O(6) bond lengths are 1.96 Å. P(1) is bonded to one O(3), one O(4), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Na(2)O8 hexagonal bipyramid,  a cornercorner with one Sb(2)O6 octahedra, and corners with two equivalent Sb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-53°. The P(1)-O(3) bond length is 1.55 Å. The P(1)-O(4) bond length is 1.49 Å. The P(1)-O(5) bond length is 1.57 Å. The P(1)-O(7) bond length is 1.54 Å. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to one Na(1), one Sb(2), and one P(1) atom. In the second O site, O(6) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Sb(1), and one Sb(2) atom. In the third O site, O(7) is bonded in a 2-coordinate geometry to one Na(1), one Sb(1), and one P(1) atom. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one Na(2), one Sb(1), and one Sb(2) atom. In the fifth O site, O(2) is bonded in a 3-coordinate geometry to one Na(2) and two equivalent Sb(1) atoms. In the sixth O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Sb(1), and one P(1) atom. In the seventh O site, O(4) is bonded to one Na(2), two equivalent Na(1), and one P(1) atom to form a mixture of distorted corner and edge-sharing ONa3P tetrahedra.