Na2C2N9H5O2 crystallizes in the monoclinic P2_1/m space group. Na(1) is bonded to one N(5), one N(6), one N(8), one N(9), one O(1), and one O(2) atom to form distorted NaN4O2 octahedra that share  a cornercorner with one N(8)Na2N2 tetrahedra and faces with two equivalent Na(1)N4O2 octahedra. The Na(1)-N(5) bond length is 2.50 Å. The Na(1)-N(6) bond length is 2.49 Å. The Na(1)-N(8) bond length is 2.57 Å. The Na(1)-N(9) bond length is 2.54 Å. The Na(1)-O(1) bond length is 2.35 Å. The Na(1)-O(2) bond length is 2.39 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one N(1), one N(2), and one N(5) atom. The C(1)-N(1) bond length is 1.37 Å. The C(1)-N(2) bond length is 1.35 Å. The C(1)-N(5) bond length is 1.35 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one N(1), one N(6), and one N(9) atom. The C(2)-N(1) bond length is 1.37 Å. The C(2)-N(6) bond length is 1.35 Å. The C(2)-N(9) bond length is 1.35 Å. There are nine inequivalent N sites. In the first N site, N(1) is bonded in a trigonal planar geometry to one C(1), one C(2), and one H(5) atom. The N(1)-H(5) bond length is 1.04 Å. In the second N site, N(2) is bonded in a distorted trigonal planar geometry to one C(1), one N(3), and one H(1) atom. The N(2)-N(3) bond length is 1.35 Å. The N(2)-H(1) bond length is 1.71 Å. In the third N site, N(3) is bonded in a water-like geometry to one N(2) and one N(4) atom. The N(3)-N(4) bond length is 1.31 Å. In the fourth N site, N(4) is bonded in a water-like geometry to one N(3) and one N(5) atom. The N(4)-N(5) bond length is 1.35 Å. In the fifth N site, N(5) is bonded to two equivalent Na(1), one C(1), and one N(4) atom to form distorted NNa2CN tetrahedra that share corners with two equivalent N(8)Na2N2 tetrahedra and  an edgeedge with one N(6)Na2CN tetrahedra. In the sixth N site, N(6) is bonded to two equivalent Na(1), one C(2), and one N(7) atom to form distorted NNa2CN tetrahedra that share corners with three equivalent N(8)Na2N2 tetrahedra and  an edgeedge with one N(5)Na2CN tetrahedra. The N(6)-N(7) bond length is 1.35 Å. In the seventh N site, N(7) is bonded in a distorted trigonal planar geometry to one N(6), one N(8), and one H(4) atom. The N(7)-N(8) bond length is 1.31 Å. The N(7)-H(4) bond length is 1.79 Å. In the eighth N site, N(8) is bonded to two equivalent Na(1), one N(7), and one N(9) atom to form NNa2N2 tetrahedra that share corners with two equivalent Na(1)N4O2 octahedra, corners with two equivalent N(5)Na2CN tetrahedra, and corners with three equivalent N(6)Na2CN tetrahedra. The corner-sharing octahedral tilt angles are 59°. The N(8)-N(9) bond length is 1.36 Å. In the ninth N site, N(9) is bonded in a 4-coordinate geometry to two equivalent Na(1), one C(2), and one N(8) atom. There are five inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one N(2) and one O(1) atom. The H(1)-O(1) bond length is 1.01 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(1) atom. The H(2)-O(1) bond length is 0.98 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(2) atom. The H(3)-O(2) bond length is 0.99 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one N(7) and one O(2) atom. The H(4)-O(2) bond length is 1.00 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one N(1) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted water-like geometry to two equivalent Na(1), one H(1), and one H(2) atom. In the second O site, O(2) is bonded in a distorted water-like geometry to two equivalent Na(1), one H(3), and one H(4) atom. Linkers: 2 [N]1N=NN=C1NC1=NN=N[N]1. Metal clusters: 4 [Na]. The MOF has largest included sphere 1.43 A, density 1.92 g/cm3, surface area 2447.29 m2/g, accessible volume 0.03 cm3/g