KC4N2H4O3Br crystallizes in the monoclinic P2_1/c space group. K(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent Br(1) atoms. There is one shorter (2.73 Å) and one longer (2.80 Å) K(1)-O(1) bond length. There is one shorter (2.78 Å) and one longer (2.83 Å) K(1)-O(2) bond length. There is one shorter (2.99 Å) and one longer (3.00 Å) K(1)-O(3) bond length. There is one shorter (3.46 Å) and one longer (3.60 Å) K(1)-Br(1) bond length. There are four inequivalent C sites. In the first C site, C(4) is bonded in a distorted water-like geometry to one C(1), one H(1), and one H(2) atom. The C(4)-C(1) bond length is 1.50 Å. The C(4)-H(1) bond length is 1.10 Å. The C(4)-H(2) bond length is 1.11 Å. In the second C site, C(1) is bonded in a distorted trigonal planar geometry to one C(4), one N(2), and one O(3) atom. The C(1)-N(2) bond length is 1.38 Å. The C(1)-O(3) bond length is 1.23 Å. In the third C site, C(2) is bonded in a distorted bent 120 degrees geometry to one N(1) and one O(2) atom. The C(2)-N(1) bond length is 1.37 Å. The C(2)-O(2) bond length is 1.24 Å. In the fourth C site, C(3) is bonded in a trigonal planar geometry to one N(1), one N(2), and one O(1) atom. The C(3)-N(1) bond length is 1.38 Å. The C(3)-N(2) bond length is 1.38 Å. The C(3)-O(1) bond length is 1.24 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 C(3), and one H(3) atom. The N(1)-H(3) bond length is 1.05 Å. In the second N site, N(2) is bonded in a trigonal planar geometry to one C(1), one C(3), and one H(4) atom. The N(2)-H(4) bond length is 1.04 Å. There are four inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(4) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(4) atom. In the third H site, H(3) is bonded in a single-bond geometry to one N(1) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one N(2) atom. There are three 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(3) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(1) and one C(2) atom. In the third O site, O(3) is bonded in a single-bond geometry to two equivalent K(1) and one C(1) atom. Br(1) is bonded in a 1-coordinate geometry to two equivalent K(1) atoms. Linkers: 4 O=C1CC(=O)NC(=O)N1. Metal clusters: 4 [K]. RCSR code: nia. The MOF has largest included sphere 1.62 A, density 2.13 g/cm3, surface area 2058.13 m2/g, accessible volume 0.07 cm3/g