Na2ZnH4(SO4)2 crystallizes in the monoclinic P2_1/c space group. Na(1) is bonded to one O(1), one O(2), and two equivalent O(4) atoms to form distorted NaO4 tetrahedra that share corners with four equivalent S(1)O4 tetrahedra and  an edgeedge with one Na(1)O4 tetrahedra. Zn(1) is bonded in a distorted linear geometry to two equivalent H(2) and two equivalent O(3) atoms. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one H(2) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one Zn(1) and one H(1) 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 four equivalent Na(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Na(1) and one S(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Na(1) and one S(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Zn(1) and one S(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to two equivalent Na(1) and one S(1) atom.
Na2ZnH4(SO4)2 crystallizes in the monoclinic P2_1/c space group. Na(1) is bonded to one O(1), one O(2), and two equivalent O(4) atoms to form distorted NaO4 tetrahedra that share corners with four equivalent S(1)O4 tetrahedra and  an edgeedge with one Na(1)O4 tetrahedra. The Na(1)-O(1) bond length is 2.29 Å. The Na(1)-O(2) bond length is 2.41 Å. There is one shorter (2.32 Å) and one longer (2.36 Å) Na(1)-O(4) bond length. Zn(1) is bonded in a distorted linear geometry to two equivalent H(2) and two equivalent O(3) atoms. Both Zn(1)-H(2) bond lengths are 2.10 Å. Both Zn(1)-O(3) bond lengths are 1.86 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one H(2) atom. The H(1)-H(2) bond length is 0.76 Å. In the second H site, H(2) is bonded in a distorted single-bond geometry to one Zn(1) and one H(1) 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 four equivalent Na(1)O4 tetrahedra. The S(1)-O(1) bond length is 1.47 Å. The S(1)-O(2) bond length is 1.47 Å. The S(1)-O(3) bond length is 1.57 Å. The S(1)-O(4) bond length is 1.49 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Na(1) and one S(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Na(1) and one S(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Zn(1) and one S(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to two equivalent Na(1) and one S(1) atom.