ErH3(CO2)4(CH2)2 crystallizes in the monoclinic C2/c space group. The structure consists of sixteen 02329_fluka molecules inside a ErH3(CO2)4 framework. In the ErH3(CO2)4 framework, Er(1) is bonded in a 9-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(8), and two equivalent O(7) atoms. The Er(1)-O(1) bond length is 2.38 Å. The Er(1)-O(2) bond length is 2.31 Å. The Er(1)-O(3) bond length is 2.68 Å. The Er(1)-O(4) bond length is 2.26 Å. The Er(1)-O(5) bond length is 2.44 Å. The Er(1)-O(6) bond length is 2.33 Å. The Er(1)-O(8) bond length is 2.47 Å. There is one shorter (2.34 Å) and one longer (2.44 Å) Er(1)-O(7) bond length. There are four inequivalent C sites. In the first C site, C(2) is bonded in a distorted single-bond geometry to one O(5) atom. The C(2)-O(5) bond length is 1.45 Å. In the second C site, C(3) is bonded in a distorted bent 120 degrees geometry to one O(2) and one O(6) atom. The C(3)-O(2) bond length is 1.28 Å. The C(3)-O(6) bond length is 1.26 Å. In the third C site, C(5) is bonded in a distorted bent 120 degrees geometry to one O(1) and one O(8) atom. The C(5)-O(1) bond length is 1.27 Å. The C(5)-O(8) bond length is 1.29 Å. In the fourth C site, C(6) is bonded in a distorted bent 120 degrees geometry to one O(3) and one O(7) atom. The C(6)-O(3) bond length is 1.27 Å. The C(6)-O(7) bond length is 1.28 Å. There are three inequivalent H sites. In the first H site, H(1) is bonded in a distorted linear geometry to one O(3) and one O(4) atom. The H(1)-O(3) bond length is 1.63 Å. The H(1)-O(4) bond length is 1.00 Å. In the second H site, H(2) is bonded in a distorted single-bond geometry to one O(2) and one O(4) atom. The H(2)-O(2) bond length is 1.65 Å. The H(2)-O(4) bond length is 1.00 Å. In the third H site, H(3) is bonded in a distorted bent 150 degrees geometry to one O(5) and one O(8) atom. The H(3)-O(5) bond length is 1.01 Å. The H(3)-O(8) bond length is 1.63 Å. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a distorted water-like geometry to one Er(1), one C(2), and one H(3) atom. In the second O site, O(6) is bonded in a distorted single-bond geometry to one Er(1) and one C(3) atom. In the third O site, O(7) is bonded in a distorted single-bond geometry to two equivalent Er(1) and one C(6) atom. In the fourth O site, O(8) is bonded in a 3-coordinate geometry to one Er(1), one C(5), and one H(3) atom. In the fifth O site, O(1) is bonded in a distorted single-bond geometry to one Er(1) and one C(5) atom. In the sixth O site, O(2) is bonded in a distorted trigonal planar geometry to one Er(1), one C(3), and one H(2) atom. In the seventh O site, O(3) is bonded in a 2-coordinate geometry to one Er(1), one C(6), and one H(1) atom. In the eighth O site, O(4) is bonded in a distorted water-like geometry to one Er(1), one H(1), and one H(2) atom. Linkers: 4 [O]C(=O)CC(O)(CC([O])=O)C([O])=O. Metal clusters: 4 [Er]. The MOF has largest included sphere 1.86 A, density 2.88 g/cm3, surface area 2186.83 m2/g, accessible volume 0.05 cm3/g