ZnC4N2H4O3 crystallizes in the orthorhombic Ima2 space group. Zn(1) is bonded in a distorted tetrahedral geometry to one N(1), one N(2), one O(1), and one O(3) atom. The Zn(1)-N(1) bond length is 2.00 Å. The Zn(1)-N(2) bond length is 2.01 Å. The Zn(1)-O(1) bond length is 1.99 Å. The Zn(1)-O(3) bond length is 2.02 Å. There are six inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to two equivalent N(1) and one H(1) atom. Both C(1)-N(1) bond lengths are 1.33 Å. The C(1)-H(1) bond length is 1.09 Å. In the second C site, C(2) is bonded in a 3-coordinate geometry to one C(3), one N(1), and one O(1) atom. The C(2)-C(3) bond length is 1.40 Å. The C(2)-N(1) bond length is 1.38 Å. The C(2)-O(1) bond length is 1.29 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to two equivalent C(2) and one H(2) atom. The C(3)-H(2) bond length is 1.09 Å. In the fourth C site, C(4) is bonded in a trigonal planar geometry to two equivalent N(2) and one H(3) atom. Both C(4)-N(2) bond lengths are 1.33 Å. The C(4)-H(3) bond length is 1.09 Å. In the fifth C site, C(5) is bonded in a 3-coordinate geometry to one C(6), one N(2), and one O(2) atom. The C(5)-C(6) bond length is 1.40 Å. The C(5)-N(2) bond length is 1.40 Å. The C(5)-O(2) bond length is 1.29 Å. In the sixth C site, C(6) is bonded in a distorted single-bond geometry to two equivalent C(5) and one H(4) atom. The C(6)-H(4) bond length is 1.09 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded in a trigonal planar geometry to one Zn(1), one C(1), and one C(2) atom. In the second N site, N(2) is bonded in a trigonal planar geometry to one Zn(1), one C(4), and one C(5) atom. There are six inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(3) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(4) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(6) atom. In the fifth H site, H(5) is bonded in a distorted single-bond geometry to one O(2) and one O(3) atom. The H(5)-O(2) bond length is 1.68 Å. The H(5)-O(3) bond length is 1.00 Å. In the sixth H site, H(6) is bonded in a distorted single-bond geometry to one O(2) and one O(3) atom. The H(6)-O(2) bond length is 1.67 Å. The H(6)-O(3) bond length is 1.00 Å. There are three inequivalent O sites. In the first O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Zn(1), one H(5), and one H(6) atom. In the second O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Zn(1) and one C(2) atom. In the third O site, O(2) is bonded in a distorted single-bond geometry to one C(5), one H(5), and one H(6) atom. Linkers: 4 O=C1[CH]C(=O)N=C[N]1. Metal clusters: 4 [Zn]. The MOF has largest included sphere 1.87 A, density 2.15 g/cm3, surface area 3470.61 m2/g, accessible volume 0.11 cm3/g