LaH9(C2O3)3 crystallizes in the monoclinic Cc space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 9-coordinate geometry to one O(1), one O(16), one O(17), one O(18), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. The La(1)-O(1) bond length is 2.45 Å. The La(1)-O(16) bond length is 2.87 Å. The La(1)-O(17) bond length is 2.87 Å. The La(1)-O(18) bond length is 2.87 Å. The La(1)-O(2) bond length is 2.45 Å. The La(1)-O(3) bond length is 2.45 Å. The La(1)-O(4) bond length is 2.45 Å. The La(1)-O(5) bond length is 2.45 Å. The La(1)-O(6) bond length is 2.45 Å. In the second La site, La(2) is bonded in a 9-coordinate geometry to two equivalent O(9,10); three equivalent O(13,14,15); and four equivalent O(7,8,11,12) atoms. Both La(2)-O(9,10) bond lengths are 2.52 Å. All La(2)-O(13,14,15) bond lengths are 2.57 Å. All La(2)-O(7,8,11,12) bond lengths are 2.52 Å. There are two inequivalent C sites. In the first C site, C(1,2,3,4,5,6) is bonded in a distorted bent 120 degrees geometry to one O(1) and one O(7,8,11,12) atom. The C(1,2,3,4,5,6)-O(1) bond length is 1.27 Å. The C(1,2,3,4,5,6)-O(7,8,11,12) bond length is 1.26 Å. In the second C site, C(7,8,9,10,11,12) is bonded in a distorted trigonal non-coplanar geometry to one H(13,14,15,16,17,18); one H(7,8,9,10,11,12); and one O(13,14,15) atom. The C(7,8,9,10,11,12)-H(13,14,15,16,17,18) bond length is 1.10 Å. The C(7,8,9,10,11,12)-H(7,8,9,10,11,12) bond length is 1.11 Å. The C(7,8,9,10,11,12)-O(13,14,15) bond length is 1.42 Å. There are four inequivalent H sites. In the first H site, H(1,2,3) is bonded in a single-bond geometry to one O(16) atom. The H(1,2,3)-O(16) bond length is 0.97 Å. In the second H site, H(4,5,6) is bonded in a single-bond geometry to one O(16) atom. The H(4,5,6)-O(16) bond length is 0.97 Å. In the third H site, H(7,8,9,10,11,12) is bonded in a single-bond geometry to one C(7,8,9,10,11,12) atom. In the fourth H site, H(13,14,15,16,17,18) is bonded in a single-bond geometry to one C(7,8,9,10,11,12) atom. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one La(1) and one C(1,2,3,4,5,6) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one La(1) and one C(1,2,3,4,5,6) atom. The O(2)-C(1,2,3,4,5,6) bond length is 1.27 Å. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one La(1) and one C(1,2,3,4,5,6) atom. The O(3)-C(1,2,3,4,5,6) bond length is 1.27 Å. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one La(1) and one C(1,2,3,4,5,6) atom. The O(4)-C(1,2,3,4,5,6) bond length is 1.27 Å. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one La(1) and one C(1,2,3,4,5,6) atom. The O(5)-C(1,2,3,4,5,6) bond length is 1.27 Å. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one La(1) and one C(1,2,3,4,5,6) atom. The O(6)-C(1,2,3,4,5,6) bond length is 1.27 Å. In the seventh O site, O(7,8,11,12) is bonded in a distorted bent 120 degrees geometry to one La(2) and one C(1,2,3,4,5,6) atom. In the eighth O site, O(9,10) is bonded in a distorted bent 120 degrees geometry to one La(2) and one C(1,2,3,4,5,6) atom. The O(9,10)-C(1,2,3,4,5,6) bond length is 1.26 Å. In the ninth O site, O(13,14,15) is bonded in a distorted bent 120 degrees geometry to one La(2) and two equivalent C(7,8,9,10,11,12) atoms. In the tenth O site, O(16) is bonded in a water-like geometry to one La(1); one H(1,2,3); and one H(4,5,6) atom. In the eleventh O site, O(17) is bonded in a water-like geometry to one La(1); one H(1,2,3); and one H(4,5,6) atom. The O(17)-H(1,2,3) bond length is 0.97 Å. The O(17)-H(4,5,6) bond length is 0.97 Å. In the twelfth O site, O(18) is bonded in a water-like geometry to one La(1); one H(1,2,3); and one H(4,5,6) atom. The O(18)-H(1,2,3) bond length is 0.97 Å. The O(18)-H(4,5,6) bond length is 0.97 Å. Linkers: 6 [O]C(=O)COCC([O])=O. Metal clusters: 4 [La]. The MOF has largest included sphere 3.66 A, density 1.84 g/cm3, surface area 3138.86 m2/g, accessible volume 0.18 cm3/g