Na2ZnP2O7 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 8-coordinate geometry to one O(2), one O(3), one O(6), one O(7), two equivalent O(4), and two equivalent O(5) atoms. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), one O(5), and one O(7) atom. Zn(1) is bonded to one O(2), one O(3), one O(6), and one O(7) atom to form ZnO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with two equivalent Zn(1)O4 tetrahedra. In the second P site, P(2) is bonded to one O(1), one O(2), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Zn(1)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(2), one P(1), and one P(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(1), one Zn(1), and one P(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Zn(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(1), one Zn(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), one Zn(1), and one P(2) atom.
Na2ZnP2O7 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 8-coordinate geometry to one O(2), one O(3), one O(6), one O(7), two equivalent O(4), and two equivalent O(5) atoms. The Na(1)-O(2) bond length is 2.54 Å. The Na(1)-O(3) bond length is 2.88 Å. The Na(1)-O(6) bond length is 2.49 Å. The Na(1)-O(7) bond length is 2.99 Å. There is one shorter (2.58 Å) and one longer (2.70 Å) Na(1)-O(4) bond length. There is one shorter (2.55 Å) and one longer (2.64 Å) Na(1)-O(5) bond length. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), one O(5), and one O(7) atom. The Na(2)-O(1) bond length is 2.55 Å. The Na(2)-O(3) bond length is 2.50 Å. The Na(2)-O(4) bond length is 2.37 Å. The Na(2)-O(5) bond length is 2.38 Å. The Na(2)-O(7) bond length is 2.52 Å. Zn(1) is bonded to one O(2), one O(3), one O(6), and one O(7) atom to form ZnO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. The Zn(1)-O(2) bond length is 1.98 Å. The Zn(1)-O(3) bond length is 1.99 Å. The Zn(1)-O(6) bond length is 1.98 Å. The Zn(1)-O(7) bond length is 1.98 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one P(2)O4 tetrahedra and corners with two equivalent Zn(1)O4 tetrahedra. The P(1)-O(1) bond length is 1.65 Å. The P(1)-O(3) bond length is 1.55 Å. The P(1)-O(4) bond length is 1.51 Å. The P(1)-O(6) bond length is 1.54 Å. In the second P site, P(2) is bonded to one O(1), one O(2), one O(5), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra and corners with two equivalent Zn(1)O4 tetrahedra. The P(2)-O(1) bond length is 1.64 Å. The P(2)-O(2) bond length is 1.54 Å. The P(2)-O(5) bond length is 1.52 Å. The P(2)-O(7) bond length is 1.55 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(2), one P(1), and one P(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(1), one Zn(1), and one P(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Zn(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(1), one Zn(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), one Zn(1), and one P(2) atom.