Na2H4Te2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(7) atoms to form edge-sharing NaO5 trigonal bipyramids. In the second Na site, Na(2) is bonded to one O(3), one O(5), two equivalent O(2), and two equivalent O(6) atoms to form distorted edge-sharing NaO6 octahedra. There are four inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(7) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(7) atom. In the third H site, H(3) is bonded in a single-bond geometry to one O(4) and one O(6) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(6) atom. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded in a distorted see-saw-like geometry to one O(3), one O(4), and two equivalent O(1) atoms. In the second Te site, Te(2) is bonded in a distorted see-saw-like geometry to one O(3), one O(5), and two equivalent O(2) atoms. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(1) and two equivalent Te(1) atoms. In the second O site, O(2) is bonded to two equivalent Na(2) and two equivalent Te(2) atoms to form edge-sharing ONa2Te2 tetrahedra. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2), one Te(1), and one Te(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one H(3), and one Te(1) atom. In the fifth O site, O(5) is bonded in a distorted water-like geometry to one Na(2) and one Te(2) atom. In the sixth O site, O(6) is bonded in a distorted water-like geometry to two equivalent Na(2), one H(3), and one H(4) atom. In the seventh O site, O(7) is bonded in a distorted water-like geometry to two equivalent Na(1), one H(1), and one H(2) atom.
Na2H4Te2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(7) atoms to form edge-sharing NaO5 trigonal bipyramids. The Na(1)-O(4) bond length is 2.42 Å. There is one shorter (2.41 Å) and one longer (2.42 Å) Na(1)-O(1) bond length. There is one shorter (2.40 Å) and one longer (2.46 Å) Na(1)-O(7) bond length. In the second Na site, Na(2) is bonded to one O(3), one O(5), two equivalent O(2), and two equivalent O(6) atoms to form distorted edge-sharing NaO6 octahedra. The Na(2)-O(3) bond length is 2.42 Å. The Na(2)-O(5) bond length is 2.43 Å. There is one shorter (2.37 Å) and one longer (2.61 Å) Na(2)-O(2) bond length. There is one shorter (2.37 Å) and one longer (2.57 Å) Na(2)-O(6) bond length. There are four inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(7) atom. The H(1)-O(7) bond length is 1.00 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(7) atom. The H(2)-O(7) bond length is 1.00 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(4) and one O(6) atom. The H(3)-O(4) bond length is 1.75 Å. The H(3)-O(6) bond length is 1.00 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(6) atom. The H(4)-O(6) bond length is 0.99 Å. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded in a distorted see-saw-like geometry to one O(3), one O(4), and two equivalent O(1) atoms. The Te(1)-O(3) bond length is 1.96 Å. The Te(1)-O(4) bond length is 1.88 Å. There is one shorter (1.90 Å) and one longer (2.50 Å) Te(1)-O(1) bond length. In the second Te site, Te(2) is bonded in a distorted see-saw-like geometry to one O(3), one O(5), and two equivalent O(2) atoms. The Te(2)-O(3) bond length is 2.06 Å. The Te(2)-O(5) bond length is 1.87 Å. There is one shorter (1.94 Å) and one longer (2.17 Å) Te(2)-O(2) bond length. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(1) and two equivalent Te(1) atoms. In the second O site, O(2) is bonded to two equivalent Na(2) and two equivalent Te(2) atoms to form edge-sharing ONa2Te2 tetrahedra. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(2), one Te(1), and one Te(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one H(3), and one Te(1) atom. In the fifth O site, O(5) is bonded in a distorted water-like geometry to one Na(2) and one Te(2) atom. In the sixth O site, O(6) is bonded in a distorted water-like geometry to two equivalent Na(2), one H(3), and one H(4) atom. In the seventh O site, O(7) is bonded in a distorted water-like geometry to two equivalent Na(1), one H(1), and one H(2) atom.