Cu4H9(CN2)9 crystallizes in the hexagonal P6_3/m space group. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a rectangular see-saw-like geometry to one N(1), one N(2), one N(4), and one N(6) atom. The Cu(1)-N(1) bond length is 1.95 Å. The Cu(1)-N(2) bond length is 2.09 Å. The Cu(1)-N(4) bond length is 2.03 Å. The Cu(1)-N(6) bond length is 2.06 Å. In the second Cu site, Cu(2) is bonded in an octahedral geometry to three equivalent N(3) and three equivalent N(5) atoms. All Cu(2)-N(3) bond lengths are 2.14 Å. All Cu(2)-N(5) bond lengths are 2.17 Å. There are four inequivalent C sites. In the first C site, C(3) is bonded in a distorted trigonal planar geometry to one C(4) and two equivalent N(6) atoms. The C(3)-C(4) bond length is 1.53 Å. Both C(3)-N(6) bond lengths are 1.31 Å. In the second C site, C(4) is bonded in a single-bond geometry to one C(3) atom. In the third C site, C(1) is bonded in a distorted trigonal planar geometry to one C(2), one N(1), and one N(4) atom. The C(1)-C(2) bond length is 1.52 Å. The C(1)-N(1) bond length is 1.33 Å. The C(1)-N(4) bond length is 1.34 Å. In the fourth C site, C(2) is bonded in a trigonal non-coplanar geometry to one C(1) and three equivalent H(1,2,3) atoms. All C(2)-H(1,2,3) bond lengths are 0.96 Å. There are six inequivalent N sites. In the first N site, N(1) is bonded in a 2-coordinate 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(1), one N(1), and one N(3) atom. The N(2)-N(3) bond length is 1.30 Å. In the third N site, N(3) is bonded in a distorted trigonal planar geometry to one Cu(2), one N(2), and one N(4) atom. The N(3)-N(4) bond length is 1.32 Å. In the fourth N site, N(4) is bonded in a distorted trigonal planar geometry to one Cu(1), one C(1), and one N(3) atom. In the fifth N site, N(5) is bonded in a distorted trigonal planar geometry to one Cu(2), one N(5), and one N(6) atom. The N(5)-N(5) bond length is 1.31 Å. The N(5)-N(6) bond length is 1.33 Å. In the sixth N site, N(6) is bonded in a distorted trigonal planar geometry to one Cu(1), one C(3), and one N(5) atom. H(1,2,3) is bonded in a single-bond geometry to one C(2) atom. Linkers: 6 [C]C1=NN=N[N]1 ,12 CC1=NN=N[N]1. Metal clusters: 16 [Cu]. The MOF has largest included sphere 5.90 A, density 1.50 g/cm3, surface area 3194.25 m2/g, accessible volume 0.39 cm3/g