KC6N3H2O7 crystallizes in the orthorhombic Ibca space group. K(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(4), and four equivalent O(2) atoms. Both K(1)-O(1) bond lengths are 2.77 Å. Both K(1)-O(4) bond lengths are 2.78 Å. There are two shorter (2.88 Å) and two longer (2.90 Å) K(1)-O(2) bond lengths. There are four inequivalent C sites. In the first 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(2) bond length is 1.38 Å. The C(3)-C(4) bond length is 1.40 Å. The C(3)-H(1) bond length is 1.09 Å. In the second C site, C(4) is bonded in a distorted trigonal planar geometry to two equivalent C(3) and one N(2) atom. The C(4)-N(2) bond length is 1.44 Å. In the third C site, C(1) is bonded in a distorted single-bond geometry to two equivalent C(2) and one O(1) atom. Both C(1)-C(2) bond lengths are 1.47 Å. The C(1)-O(1) bond length is 1.25 Å. In the fourth C site, C(2) is bonded in a distorted trigonal planar geometry to one C(1), one C(3), and one N(1) atom. The C(2)-N(1) bond length is 1.45 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded in a trigonal planar geometry to one C(2), one O(2), and one O(3) atom. The N(1)-O(2) bond length is 1.25 Å. The N(1)-O(3) bond length is 1.25 Å. In the second N site, N(2) is bonded in a trigonal planar geometry to one C(4) and two equivalent O(4) atoms. Both N(2)-O(4) bond lengths are 1.25 Å. H(1) is bonded in a single-bond geometry to one C(3) atom. There are four 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 C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(1) and one N(1) atom. In the third O site, O(3) is bonded in a single-bond geometry to one N(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one K(1) and one N(2) atom. Linkers: 4 O=C1C([N+](=O)[O-])=C[C]([N+](=O)[O-])C=C1[N+](=O)[O-]. Metal clusters: 4 [K]. The MOF has largest included sphere 1.40 A, density 1.93 g/cm3, surface area 2408.27 m2/g, accessible volume 0.05 cm3/g