Cd2C2N4H4SO5 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to one N(1), one N(4), one O(1), one O(2), and one O(5) atom to form CdN2O3 square pyramids that share corners with two equivalent Cd(2)N2O4 octahedra and corners with two equivalent S(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 63-68°. The Cd(1)-N(1) bond length is 2.42 Å. The Cd(1)-N(4) bond length is 2.49 Å. The Cd(1)-O(1) bond length is 2.27 Å. The Cd(1)-O(2) bond length is 2.29 Å. The Cd(1)-O(5) bond length is 2.27 Å. In the second Cd site, Cd(2) is bonded to one N(2), one N(3), one O(3), one O(4), and two equivalent O(5) atoms to form CdN2O4 octahedra that share corners with two equivalent Cd(2)N2O4 octahedra, corners with two equivalent Cd(1)N2O3 square pyramids, and corners with two equivalent S(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 76°. The Cd(2)-N(2) bond length is 2.32 Å. The Cd(2)-N(3) bond length is 2.31 Å. The Cd(2)-O(3) bond length is 2.28 Å. The Cd(2)-O(4) bond length is 2.35 Å. There is one shorter (2.21 Å) and one longer (2.32 Å) Cd(2)-O(5) bond length. There are two inequivalent C sites. In the first C site, C(1) is bonded in a distorted trigonal planar geometry to one C(2), one N(1), and one N(4) atom. The C(1)-C(2) bond length is 1.49 Å. The C(1)-N(1) bond length is 1.35 Å. The C(1)-N(4) bond length is 1.35 Å. In the second C site, C(2) is bonded in a trigonal non-coplanar geometry to one C(1); one H(4); and two equivalent H(2,3) atoms. The C(2)-H(4) bond length is 0.96 Å. Both C(2)-H(2,3) bond lengths are 0.96 Å. There are four inequivalent N sites. In the first N site, N(1) is bonded in a 3-coordinate geometry to one Cd(1), one C(1), and one N(2) atom. The N(1)-N(2) bond length is 1.38 Å. In the second N site, N(2) is bonded in a trigonal planar geometry to one Cd(2), one N(1), and one N(3) atom. The N(2)-N(3) bond length is 1.30 Å. In the third N site, N(3) is bonded in a distorted trigonal planar geometry to one Cd(2), one N(2), and one N(4) atom. The N(3)-N(4) bond length is 1.30 Å. In the fourth N site, N(4) is bonded in a 3-coordinate geometry to one Cd(1), one C(1), and one N(3) atom. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(5) atom. The H(1)-O(5) bond length is 0.84 Å. In the second H site, H(2,3) is bonded in a single-bond geometry to one C(2) atom. In the third H site, H(4) is bonded in a single-bond geometry to one C(2) 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 Cd(2)N2O4 octahedra and corners with two equivalent Cd(1)N2O3 square pyramids. The corner-sharing octahedral tilt angles are 54°. 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 1.50 Å. The S(1)-O(4) bond length is 1.44 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Cd(1) and one S(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Cd(1) and one S(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Cd(2) and one S(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Cd(2) and one S(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Cd(1), two equivalent Cd(2), and one H(1) atom. Linkers: 4 CC1=NN=N[N]1. Metal clusters: 8 [Cd]. The MOF has largest included sphere 4.44 A, density 2.43 g/cm3, surface area 2440.84 m2/g, accessible volume 0.12 cm3/g