CuCN2HBr crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to two equivalent N(1), one Br(1), and one Br(2) atom to form distorted corner-sharing CuBr2N2 tetrahedra. Both Cu(1)-N(1) bond lengths are 1.96 Å. The Cu(1)-Br(1) bond length is 2.49 Å. The Cu(1)-Br(2) bond length is 2.39 Å. In the second Cu site, Cu(2) is bonded to two equivalent N(2), one Br(1), and one Br(2) atom to form distorted corner-sharing CuBr2N2 tetrahedra. Both Cu(2)-N(2) bond lengths are 1.96 Å. The Cu(2)-Br(1) bond length is 2.39 Å. The Cu(2)-Br(2) bond length is 2.49 Å. C(1) is bonded in a trigonal planar geometry to one N(1), one N(2), and one H(1) atom. The C(1)-N(1) bond length is 1.34 Å. The C(1)-N(2) bond length is 1.34 Å. The C(1)-H(1) bond length is 1.09 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal planar geometry to one Cu(1), one C(1), and one N(2) atom. The N(1)-N(2) bond length is 1.36 Å. In the second N site, N(2) is bonded in a distorted trigonal planar geometry to one Cu(2), one C(1), and one N(1) atom. H(1) is bonded in a single-bond geometry to one C(1) atom. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded in a bent 120 degrees geometry to one Cu(1) and one Cu(2) atom. In the second Br site, Br(2) is bonded in a bent 120 degrees geometry to one Cu(1) and one Cu(2) atom. Linkers: 2 c1nncnn1. Metal clusters: 4 [Cu]. The MOF has largest included sphere 2.10 A, density 3.51 g/cm3, surface area 1913.92 m2/g, accessible volume 0.06 cm3/g