KC4H3(NO)6 crystallizes in the monoclinic P2_1/c space group. K(1) is bonded in a 8-coordinate geometry to one N(1), one O(2), one O(4), one O(6), two equivalent O(1), and two equivalent O(3) atoms. The K(1)-N(1) bond length is 2.96 Å. The K(1)-O(2) bond length is 3.03 Å. The K(1)-O(4) bond length is 3.01 Å. The K(1)-O(6) bond length is 2.83 Å. There is one shorter (2.79 Å) and one longer (2.80 Å) K(1)-O(1) bond length. There is one shorter (2.80 Å) and one longer (2.84 Å) K(1)-O(3) bond length. There are four inequivalent C sites. In the first C site, C(1) is bonded in a distorted single-bond geometry to one C(2), one C(4), and one N(1) atom. The C(1)-C(2) bond length is 1.43 Å. The C(1)-C(4) bond length is 1.46 Å. The C(1)-N(1) bond length is 1.33 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(5) atom. The C(2)-C(3) bond length is 1.42 Å. The C(2)-N(5) bond length is 1.38 Å. In the third C site, C(3) is bonded in a distorted bent 120 degrees geometry to one C(2), one N(2), and one N(6) atom. The C(3)-N(2) bond length is 1.35 Å. The C(3)-N(6) bond length is 1.33 Å. In the fourth C site, C(4) is bonded in a distorted trigonal planar geometry to one C(1), one N(3), and one N(4) atom. The C(4)-N(3) bond length is 1.39 Å. The C(4)-N(4) bond length is 1.39 Å. There are six inequivalent N sites. In the first N site, N(1) is bonded in a distorted single-bond geometry to one K(1) and one C(1) atom. In the second N site, N(2) is bonded in a 2-coordinate geometry to one C(3) and one H(1) atom. The N(2)-H(1) bond length is 1.02 Å. In the third N site, N(3) is bonded in a trigonal planar geometry to one C(4), one O(1), and one O(2) atom. The N(3)-O(1) bond length is 1.26 Å. The N(3)-O(2) bond length is 1.27 Å. In the fourth N site, N(4) is bonded in a trigonal planar geometry to one C(4), one O(3), and one O(4) atom. The N(4)-O(3) bond length is 1.27 Å. The N(4)-O(4) bond length is 1.26 Å. In the fifth N site, N(5) is bonded in a trigonal planar geometry to one C(2), one O(5), and one O(6) atom. The N(5)-O(5) bond length is 1.25 Å. The N(5)-O(6) bond length is 1.27 Å. In the sixth N site, N(6) is bonded in a trigonal planar geometry to one C(3), one H(2), and one H(3) atom. The N(6)-H(2) bond length is 1.02 Å. The N(6)-H(3) bond length is 1.02 Å. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one N(2) atom. In the second H site, H(2) is bonded in a single-bond geometry to one N(6) atom. In the third H site, H(3) is bonded in a single-bond geometry to one N(6) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent K(1) and one N(3) atom. In the second O site, O(2) is bonded in a single-bond geometry to one K(1) and one N(3) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to two equivalent K(1) and one N(4) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one K(1) and one N(4) atom. In the fifth O site, O(5) is bonded in a single-bond geometry to one N(5) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one K(1) and one N(5) atom. Linkers: 4 Nc1[nH]nc([C]([N+](=O)[O-])[N+](=O)[O-])c1[N+](=O)[O-]. Metal clusters: 4 [K]. The MOF has largest included sphere 1.38 A, density 2.02 g/cm3, surface area 2192.69 m2/g, accessible volume 0.04 cm3/g