KC3H3(N2O3)2 crystallizes in the monoclinic P2_1/c space group. K(1) is bonded in a 9-coordinate geometry to one N(2), one O(4), one O(5), two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms. The K(1)-N(2) bond length is 2.99 Å. The K(1)-O(4) bond length is 2.88 Å. The K(1)-O(5) bond length is 3.20 Å. There is one shorter (2.85 Å) and one longer (3.32 Å) K(1)-O(1) bond length. There is one shorter (2.92 Å) and one longer (2.93 Å) K(1)-O(2) bond length. There is one shorter (2.74 Å) and one longer (2.80 Å) K(1)-O(6) bond length. There are three 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(2), and one N(3) atom. The C(1)-C(2) bond length is 1.42 Å. The C(1)-N(2) bond length is 1.34 Å. The C(1)-N(3) bond length is 1.42 Å. In the second C site, C(2) is bonded in a distorted single-bond geometry to one C(1), one C(3), and one N(4) atom. The C(2)-C(3) bond length is 1.40 Å. The C(2)-N(4) bond length is 1.42 Å. In the third C site, C(3) is bonded in a distorted bent 120 degrees geometry to one C(2), one N(1), and one H(1) atom. The C(3)-N(1) bond length is 1.36 Å. The C(3)-H(1) bond length is 1.08 Å. There are four inequivalent N sites. In the first N site, N(2) is bonded in a distorted single-bond geometry to one K(1), one C(1), and one N(1) atom. The N(2)-N(1) bond length is 1.35 Å. In the second N site, N(3) is bonded in a trigonal planar geometry to one C(1), one O(2), and one O(3) atom. The N(3)-O(2) bond length is 1.25 Å. The N(3)-O(3) bond length is 1.25 Å. In the third N site, N(4) is bonded in a trigonal planar geometry to one C(2), one O(4), and one O(5) atom. The N(4)-O(4) bond length is 1.25 Å. The N(4)-O(5) bond length is 1.25 Å. In the fourth N site, N(1) is bonded in a distorted trigonal planar geometry to one C(3), one N(2), and one O(1) atom. The N(1)-O(1) bond length is 1.29 Å. There are three 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 O(6) atom. The H(2)-O(6) bond length is 0.99 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(6) atom. The H(3)-O(6) bond length is 0.98 Å. There are six inequivalent O sites. In the first O site, O(6) is bonded in a water-like geometry to two equivalent K(1), one H(2), and one H(3) atom. In the second O site, O(1) is bonded in a distorted single-bond geometry to two equivalent K(1) and one N(1) atom. In the third O site, O(5) is bonded in a single-bond geometry to one K(1) and one N(4) atom. In the fourth O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(1) and one N(3) atom. In the fifth O site, O(3) is bonded in a single-bond geometry to one N(3) atom. In the sixth O site, O(4) is bonded in a distorted single-bond geometry to one K(1) and one N(4) atom. Linkers: 4 [O]n1cc([N+](=O)[O-])c([N+](=O)[O-])n1. Metal clusters: 4 [K]. The MOF has largest included sphere 1.84 A, density 1.95 g/cm3, surface area 2193.34 m2/g, accessible volume 0.04 cm3/g