SmC5O6(CH)2 crystallizes in the orthorhombic Pnma space group. The structure consists of eight 02329_fluka molecules inside a SmC5O6 framework. In the SmC5O6 framework, Sm(1) is bonded in a 9-coordinate geometry to one O(4), two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. The Sm(1)-O(4) bond length is 2.65 Å. Both Sm(1)-O(1) bond lengths are 2.45 Å. There is one shorter (2.46 Å) and one longer (2.52 Å) Sm(1)-O(3) bond length. There are two shorter (2.45 Å) and two longer (2.57 Å) Sm(1)-O(2) bond lengths. There are three inequivalent C sites. In the first C site, C(4) is bonded in a distorted single-bond geometry to one O(3) atom. The C(4)-O(3) bond length is 1.32 Å. In the second 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 1.28 Å. The C(1)-O(2) bond length is 1.31 Å. In the third C site, C(2) is bonded in a distorted single-bond geometry to one O(4) atom. The C(2)-O(4) bond length is 1.39 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Sm(1) and one C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Sm(1) and one C(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to two equivalent Sm(1) and one C(4) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Sm(1) and two equivalent C(2) atoms. Linkers: 4 [O]C(=O)[C]1C=C([O])C=C(C([O])=O)O1. Metal clusters: 4 [Sm]. The MOF has largest included sphere 1.27 A, density 3.52 g/cm3, surface area 1078.02 m2/g, accessible volume 0.02 cm3/g