ZnC4N3H3O2 crystallizes in the tetragonal P4/ncc space group. Zn(1) is bonded in a 5-coordinate geometry to one N(1), one N(2), one N(3), one O(1), and one O(2) atom. The Zn(1)-N(1) bond length is 2.03 Å. The Zn(1)-N(2) bond length is 2.02 Å. The Zn(1)-N(3) bond length is 2.05 Å. The Zn(1)-O(1) bond length is 1.98 Å. The Zn(1)-O(2) bond length is 2.51 Å. There are four inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one C(2), one O(1), and one O(2) atom. The C(1)-C(2) bond length is 1.48 Å. The C(1)-O(1) bond length is 1.30 Å. The C(1)-O(2) bond length is 1.26 Å. In the second C site, C(3) is bonded in a trigonal planar geometry to one N(1), one N(2), and one H(2) atom. The C(3)-N(1) bond length is 1.36 Å. The C(3)-N(2) bond length is 1.33 Å. The C(3)-H(2) bond length is 1.09 Å. In the third C site, C(2) is bonded in a distorted trigonal planar geometry to one C(1), one C(2), and one H(1) atom. The C(2)-C(2) bond length is 1.34 Å. The C(2)-H(1) bond length is 1.09 Å. In the fourth C site, C(4) is bonded in a trigonal planar geometry to one N(1), one N(3), and one H(3) atom. The C(4)-N(1) bond length is 1.35 Å. The C(4)-N(3) bond length is 1.33 Å. The C(4)-H(3) bond length is 1.09 Å. There are three inequivalent N sites. In the first N site, N(1) is bonded in a trigonal planar geometry to one Zn(1), one C(3), and one C(4) atom. In the second N site, N(3) is bonded in a distorted trigonal planar geometry to one Zn(1), one C(4), and one N(2) atom. The N(3)-N(2) bond length is 1.37 Å. In the third N site, N(2) is bonded in a distorted trigonal planar geometry to one Zn(1), one C(3), and one N(3) atom. There are three inequivalent H sites. In the first H site, H(2) is bonded in a single-bond geometry to one C(3) atom. In the second H site, H(1) is bonded in a single-bond geometry to one C(2) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(4) atom. There are two inequivalent O sites. In the first O site, O(2) is bonded in a single-bond geometry to one Zn(1) and one C(1) atom. In the second O site, O(1) is bonded in a water-like geometry to one Zn(1) and one C(1) atom. Linkers: 8 [O]C(=O)/C=C/C([O])=O ,9 C1=NC=N[N]1 ,5 C1=NN=C[N]1. Metal clusters: 5 O=[C]O[Zn]1=NN=[Zn](O[C]=O)N=N1 ,6 [Zn]. The MOF has largest included sphere 6.50 A, density 1.20 g/cm3, surface area 3778.47 m2/g, accessible volume 0.46 cm3/g