Na2CuH4(SO5)2 crystallizes in the monoclinic P2_1/c space group. Na(1) is bonded to one O(1), one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(1)O7 pentagonal bipyramids, corners with four equivalent S(1)O4 tetrahedra, edges with two equivalent Cu(1)O6 octahedra,  an edgeedge with one Na(1)O7 pentagonal bipyramid, and  an edgeedge with one S(1)O4 tetrahedra. Cu(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form CuO6 octahedra that share corners with four equivalent S(1)O4 tetrahedra and edges with four equivalent Na(1)O7 pentagonal bipyramids. There are two inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one O(1) and one O(5) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(4) and one O(5) atom. S(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SO4 tetrahedra that share corners with two equivalent Cu(1)O6 octahedra, corners with four equivalent Na(1)O7 pentagonal bipyramids, and  an edgeedge with one Na(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 41-52°. There are five inequivalent O sites. In the first O site, O(5) is bonded in a distorted water-like geometry to one Na(1), one Cu(1), one H(1), and one H(2) atom. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one H(1), and one S(1) atom. In the third O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Cu(1), and one S(1) atom. In the fourth O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Cu(1), and one S(1) atom. In the fifth O site, O(4) is bonded to two equivalent Na(1), one H(2), and one S(1) atom to form distorted corner-sharing ONa2HS trigonal pyramids.
Na2CuH4(SO5)2 crystallizes in the monoclinic P2_1/c space group. Na(1) is bonded to one O(1), one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form distorted NaO7 pentagonal bipyramids that share corners with two equivalent Na(1)O7 pentagonal bipyramids, corners with four equivalent S(1)O4 tetrahedra, edges with two equivalent Cu(1)O6 octahedra,  an edgeedge with one Na(1)O7 pentagonal bipyramid, and  an edgeedge with one S(1)O4 tetrahedra. The Na(1)-O(1) bond length is 2.61 Å. The Na(1)-O(3) bond length is 2.52 Å. The Na(1)-O(5) bond length is 2.44 Å. There is one shorter (2.47 Å) and one longer (2.56 Å) Na(1)-O(2) bond length. There is one shorter (2.50 Å) and one longer (2.54 Å) Na(1)-O(4) bond length. Cu(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form CuO6 octahedra that share corners with four equivalent S(1)O4 tetrahedra and edges with four equivalent Na(1)O7 pentagonal bipyramids. Both Cu(1)-O(2) bond lengths are 2.55 Å. Both Cu(1)-O(3) bond lengths are 1.99 Å. Both Cu(1)-O(5) bond lengths are 1.97 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one O(1) and one O(5) atom. The H(1)-O(1) bond length is 1.68 Å. The H(1)-O(5) bond length is 1.00 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(4) and one O(5) atom. The H(2)-O(4) bond length is 1.70 Å. The H(2)-O(5) bond length is 1.00 Å. S(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SO4 tetrahedra that share corners with two equivalent Cu(1)O6 octahedra, corners with four equivalent Na(1)O7 pentagonal bipyramids, and  an edgeedge with one Na(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 41-52°. The S(1)-O(1) bond length is 1.47 Å. The S(1)-O(2) bond length is 1.49 Å. The S(1)-O(3) bond length is 1.52 Å. The S(1)-O(4) bond length is 1.50 Å. There are five inequivalent O sites. In the first O site, O(5) is bonded in a distorted water-like geometry to one Na(1), one Cu(1), one H(1), and one H(2) atom. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one H(1), and one S(1) atom. In the third O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Cu(1), and one S(1) atom. In the fourth O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Cu(1), and one S(1) atom. In the fifth O site, O(4) is bonded to two equivalent Na(1), one H(2), and one S(1) atom to form distorted corner-sharing ONa2HS trigonal pyramids.