Pr(CO2)4(CH2)2 crystallizes in the trigonal R-3 space group. The structure consists of eighteen 02329_fluka molecules inside a Pr(CO2)4 framework. In the Pr(CO2)4 framework, there are two inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a cuboctahedral geometry to six equivalent O(1) and six equivalent O(2) atoms. All Pr(1)-O(1) bond lengths are 2.58 Å. All Pr(1)-O(2) bond lengths are 2.70 Å. In the second Pr site, Pr(2) is bonded in a 9-coordinate geometry to three equivalent O(2), three equivalent O(3), and three equivalent O(4) atoms. All Pr(2)-O(2) bond lengths are 2.52 Å. All Pr(2)-O(3) bond lengths are 2.56 Å. All Pr(2)-O(4) bond lengths are 2.46 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one O(1) and one O(2) atom. The C(1)-O(1) bond length is 1.25 Å. The C(1)-O(2) bond length is 1.27 Å. In the second C site, C(3) is bonded in a distorted bent 120 degrees geometry to one O(3) and one O(4) atom. The C(3)-O(3) bond length is 1.25 Å. The C(3)-O(4) bond length is 1.26 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Pr(1) and one C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Pr(1), one Pr(2), and one C(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Pr(2) and one C(3) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Pr(2) and one C(3) atom. Linkers: 18 [O]C(=O)CC([O])=O. Metal clusters: 9 [Pr]. The MOF has largest included sphere 5.78 A, density 1.86 g/cm3, surface area 2332.22 m2/g, accessible volume 0.19 cm3/g