RbC5N3H2O5 crystallizes in the triclinic P-1 space group. Rb(1) is bonded in a 8-coordinate geometry to one N(1), one O(2), one O(5), two equivalent O(3), and three equivalent O(1) atoms. The Rb(1)-N(1) bond length is 3.12 Å. The Rb(1)-O(2) bond length is 3.02 Å. The Rb(1)-O(5) bond length is 3.22 Å. There is one shorter (2.91 Å) and one longer (3.09 Å) Rb(1)-O(3) bond length. There are a spread of Rb(1)-O(1) bond distances ranging from 2.92-3.03 Å. There are five inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one C(2), one N(1), and one O(1) atom. The C(1)-C(2) bond length is 1.46 Å. The C(1)-N(1) bond length is 1.40 Å. The C(1)-O(1) bond length is 1.25 Å. In the second C site, C(2) is bonded in a distorted trigonal planar geometry to one C(1), one C(3), and one N(2) atom. The C(2)-C(3) bond length is 1.38 Å. The C(2)-N(2) bond length is 1.44 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to one C(2), one C(4), and one H(1) atom. The C(3)-C(4) bond length is 1.39 Å. The C(3)-H(1) bond length is 1.09 Å. In the fourth C site, C(4) is bonded in a distorted trigonal planar geometry to one C(3), one C(5), and one N(3) atom. The C(4)-C(5) bond length is 1.41 Å. The C(4)-N(3) bond length is 1.43 Å. In the fifth C site, C(5) is bonded in a distorted bent 120 degrees geometry to one C(4), one N(1), and one H(2) atom. The C(5)-N(1) bond length is 1.32 Å. The C(5)-H(2) bond length is 1.09 Å. There are three inequivalent N sites. In the first N site, N(1) is bonded in a bent 120 degrees geometry to one Rb(1), one C(1), and one C(5) atom. In the second N site, N(2) is bonded in a trigonal planar geometry to one C(2), one O(2), and one O(3) atom. The N(2)-O(2) bond length is 1.24 Å. The N(2)-O(3) bond length is 1.25 Å. In the third N site, N(3) is bonded in a trigonal planar geometry to one C(4), one O(4), and one O(5) atom. The N(3)-O(4) bond length is 1.25 Å. The N(3)-O(5) bond length is 1.26 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(3) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(5) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to three equivalent Rb(1) and one C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Rb(1) and one N(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to two equivalent Rb(1) and one N(2) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one N(3) atom. In the fifth O site, O(5) is bonded in a single-bond geometry to one Rb(1) and one N(3) atom. Linkers: 2 O=C1N=C[C]([N+](=O)[O-])C=C1[N+](=O)[O-]. Metal clusters: 2 [Rb]. RCSR code: hcb. The MOF has largest included sphere 1.67 A, density 2.21 g/cm3, surface area 3338.71 m2/g, accessible volume 0.05 cm3/g