CuC3H2(N2O)2 crystallizes in the trigonal R-3 space group. Cu(1) is bonded in a rectangular see-saw-like geometry to one N(1), one N(3), one N(4), and one O(1) atom. The Cu(1)-N(1) bond length is 1.97 Å. The Cu(1)-N(3) bond length is 1.99 Å. The Cu(1)-N(4) bond length is 2.02 Å. The Cu(1)-O(1) bond length is 1.99 Å. There are three inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one N(1), one N(2), and one N(4) atom. The C(1)-N(1) bond length is 1.34 Å. The C(1)-N(2) bond length is 1.36 Å. The C(1)-N(4) bond length is 1.34 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one N(3) and one N(4) atom. The C(2)-N(3) bond length is 1.30 Å. The C(2)-N(4) bond length is 1.35 Å. In the third C site, C(3) is bonded in a distorted bent 120 degrees geometry to one O(1) and one O(2) atom. The C(3)-O(1) bond length is 1.28 Å. The C(3)-O(2) bond length is 1.23 Å. There are four 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(3) atom. The N(1)-N(3) bond length is 1.37 Å. In the second N site, N(2) is bonded in a trigonal planar geometry to one C(1) and two equivalent H(1,2) atoms. Both N(2)-H(1,2) bond lengths are 0.86 Å. In the third N site, N(3) is bonded in a 3-coordinate geometry to one Cu(1), one C(2), and one N(1) atom. In the fourth N site, N(4) is bonded in a distorted trigonal planar geometry to one Cu(1), one C(1), and one C(2) atom. H(1,2) is bonded in a single-bond geometry to one N(2) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Cu(1) and one C(3) atom. In the second O site, O(2) is bonded in a single-bond geometry to one C(3) atom. Linkers: 2 NC1=[N]=C(N=N1)C(=O)[O] ,5 NC1=NC(C([O])=O)=N[N]1 ,10 NC1=NN=C(C([O])=O)[N]1 ,1 NC1=N[N]C(C([O])=O)=N1. Metal clusters: 18 [Cu]. The MOF has largest included sphere 6.88 A, density 1.59 g/cm3, surface area 3125.56 m2/g, accessible volume 0.32 cm3/g