ZnC4N5H5O2 crystallizes in the triclinic P-1 space group. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded in a tetrahedral geometry to one N(4), one N(5), one N(8), and one O(3) atom. The Zn(1)-N(4) bond length is 1.98 Å. The Zn(1)-N(5) bond length is 1.98 Å. The Zn(1)-N(8) bond length is 2.02 Å. The Zn(1)-O(3) bond length is 2.02 Å. In the second Zn site, Zn(2) is bonded in a tetrahedral geometry to one N(10), one N(3), one N(9), and one O(1) atom. The Zn(2)-N(10) bond length is 2.00 Å. The Zn(2)-N(3) bond length is 2.02 Å. The Zn(2)-N(9) bond length is 2.00 Å. The Zn(2)-O(1) bond length is 1.98 Å. There are eight inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one N(1), one N(3), and one N(4) atom. The C(1)-N(1) bond length is 1.36 Å. The C(1)-N(3) bond length is 1.37 Å. The C(1)-N(4) bond length is 1.33 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one N(2), one N(3), and one N(5) atom. The C(2)-N(2) bond length is 1.36 Å. The C(2)-N(3) bond length is 1.37 Å. The C(2)-N(5) bond length is 1.34 Å. In the third C site, C(3) is bonded in a trigonal planar geometry to one N(6), one N(8), and one N(9) atom. The C(3)-N(6) bond length is 1.35 Å. The C(3)-N(8) bond length is 1.37 Å. The C(3)-N(9) bond length is 1.34 Å. In the fourth C site, C(4) is bonded in a trigonal planar geometry to one N(10), one N(7), and one N(8) atom. The C(4)-N(10) bond length is 1.35 Å. The C(4)-N(7) bond length is 1.34 Å. The C(4)-N(8) bond length is 1.37 Å. In the fifth C site, C(5) is bonded in a distorted bent 120 degrees geometry to one C(6), one O(1), and one O(2) atom. The C(5)-C(6) bond length is 1.49 Å. The C(5)-O(1) bond length is 1.30 Å. The C(5)-O(2) bond length is 1.26 Å. In the sixth C site, C(6) is bonded in a distorted trigonal planar geometry to one C(5), one C(7), and one H(1) atom. The C(6)-C(7) bond length is 1.34 Å. The C(6)-H(1) bond length is 1.09 Å. In the seventh C site, C(7) is bonded in a distorted trigonal planar geometry to one C(6), one C(8), and one H(2) atom. The C(7)-C(8) bond length is 1.49 Å. The C(7)-H(2) bond length is 1.09 Å. In the eighth C site, C(8) is bonded in a bent 120 degrees geometry to one C(7), one O(3), and one O(4) atom. The C(8)-O(3) bond length is 1.31 Å. The C(8)-O(4) bond length is 1.25 Å. There are ten inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal non-coplanar geometry to one C(1), one H(3), and one H(4) atom. The N(1)-H(3) bond length is 1.01 Å. The N(1)-H(4) bond length is 1.02 Å. In the second N site, N(2) is bonded in a distorted trigonal planar geometry to one C(2), one H(5), and one H(6) atom. The N(2)-H(5) bond length is 1.01 Å. The N(2)-H(6) bond length is 1.03 Å. In the third N site, N(3) is bonded in a trigonal planar geometry to one Zn(2), one C(1), and one C(2) atom. In the fourth N site, N(4) is bonded in a distorted trigonal planar geometry to one Zn(1), one C(1), and one N(5) atom. The N(4)-N(5) bond length is 1.40 Å. In the fifth N site, N(5) is bonded in a distorted trigonal planar geometry to one Zn(1), one C(2), and one N(4) atom. In the sixth N site, N(6) is bonded in a trigonal planar geometry to one C(3), one H(7), and one H(8) atom. The N(6)-H(7) bond length is 1.02 Å. The N(6)-H(8) bond length is 1.02 Å. In the seventh N site, N(7) is bonded in a trigonal planar geometry to one C(4), one H(10), and one H(9) atom. The N(7)-H(10) bond length is 1.02 Å. The N(7)-H(9) bond length is 1.03 Å. In the eighth N site, N(8) is bonded in a trigonal planar geometry to one Zn(1), one C(3), and one C(4) atom. In the ninth N site, N(9) is bonded in a distorted trigonal planar geometry to one Zn(2), one C(3), and one N(10) atom. The N(9)-N(10) bond length is 1.42 Å. In the tenth N site, N(10) is bonded in a 3-coordinate geometry to one Zn(2), one C(4), and one N(9) atom. There are ten inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(6) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(7) atom. In the third H site, H(3) is bonded in a single-bond geometry to one N(1) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one N(1) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one N(2) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one N(2) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one N(6) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one N(6) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one N(7) atom. In the tenth H site, H(10) is bonded in a single-bond geometry to one N(7) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Zn(2) and one C(5) atom. In the second O site, O(2) is bonded in a single-bond geometry to one C(5) atom. In the third O site, O(3) is bonded in a water-like geometry to one Zn(1) and one C(8) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one C(8) atom. Linkers: 4 NC1=[N]=C(N=N1)N ,2 [O]C(=O)/C=C/C([O])=O. Metal clusters: 2 O=[C]O[Zn]1[N][N][Zn](O[C]=O)[N][N]1. The MOF has largest included sphere 4.97 A, density 1.44 g/cm3, surface area 3805.00 m2/g, accessible volume 0.31 cm3/g