TmH18(C3O)6 crystallizes in the triclinic P-1 space group. Tm(1) is bonded to one O(1), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted edge-sharing TmO6 pentagonal pyramids. The Tm(1)-O(1) bond length is 2.18 Å. The Tm(1)-O(3) bond length is 2.37 Å. The Tm(1)-O(5) bond length is 2.39 Å. The Tm(1)-O(6) bond length is 2.34 Å. There is one shorter (2.36 Å) and one longer (2.48 Å) Tm(1)-O(4) bond length. There are eighteen inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one C(2), one O(1), and one O(2) atom. The C(1)-C(2) bond length is 1.51 Å. The C(1)-O(1) bond length is 1.26 Å. The C(1)-O(2) bond length is 1.22 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one C(1), one C(3), and one C(5) atom. The C(2)-C(3) bond length is 1.39 Å. The C(2)-C(5) bond length is 1.39 Å. In the third C site, C(3) is bonded in a trigonal planar geometry to one C(2), one C(4), and one C(5) atom. The C(3)-C(4) bond length is 1.47 Å. The C(3)-C(5) bond length is 1.39 Å. In the fourth C site, C(4) is bonded in a trigonal non-coplanar geometry to one C(3) and three equivalent H(1,2,3) atoms. All C(4)-H(1,2,3) bond lengths are 0.96 Å. In the fifth C site, C(5) is bonded in a trigonal planar geometry to one C(2), one C(3), and one C(6) atom. The C(5)-C(6) bond length is 1.50 Å. In the sixth C site, C(6) is bonded in a trigonal non-coplanar geometry to one C(5) and three equivalent H(4,5,6) atoms. All C(6)-H(4,5,6) bond lengths are 0.96 Å. In the seventh C site, C(7) is bonded in a distorted bent 120 degrees geometry to one C(8), one O(3), and one O(4) atom. The C(7)-C(8) bond length is 1.49 Å. The C(7)-O(3) bond length is 1.24 Å. The C(7)-O(4) bond length is 1.26 Å. In the eighth C site, C(8) is bonded in a trigonal planar geometry to one C(11), one C(7), and one C(9) atom. The C(8)-C(11) bond length is 1.39 Å. The C(8)-C(9) bond length is 1.38 Å. In the ninth C site, C(9) is bonded in a trigonal planar geometry to one C(10), one C(11), and one C(8) atom. The C(9)-C(10) bond length is 1.50 Å. The C(9)-C(11) bond length is 1.39 Å. In the tenth C site, C(10) is bonded in a trigonal non-coplanar geometry to one C(9) and three equivalent H(7,8,9) atoms. All C(10)-H(7,8,9) bond lengths are 0.96 Å. In the eleventh C site, C(11) is bonded in a trigonal planar geometry to one C(12), one C(8), and one C(9) atom. The C(11)-C(12) bond length is 1.49 Å. In the twelfth C site, C(12) is bonded in a trigonal non-coplanar geometry to one C(11) and three equivalent H(10,11,12) atoms. All C(12)-H(10,11,12) bond lengths are 0.96 Å. In the thirteenth C site, C(13) is bonded in a distorted bent 120 degrees geometry to one C(14), one O(5), and one O(6) atom. The C(13)-C(14) bond length is 1.50 Å. The C(13)-O(5) bond length is 1.25 Å. The C(13)-O(6) bond length is 1.24 Å. In the fourteenth C site, C(14) is bonded in a trigonal planar geometry to one C(13), one C(15), and one C(17) atom. The C(14)-C(15) bond length is 1.38 Å. The C(14)-C(17) bond length is 1.37 Å. In the fifteenth C site, C(15) is bonded in a trigonal planar geometry to one C(14), one C(16), and one C(17) atom. The C(15)-C(16) bond length is 1.48 Å. The C(15)-C(17) bond length is 1.39 Å. In the sixteenth C site, C(16) is bonded in a trigonal non-coplanar geometry to one C(15); one H(15); and two equivalent H(13,14) atoms. The C(16)-H(15) bond length is 0.96 Å. Both C(16)-H(13,14) bond lengths are 0.96 Å. In the seventeenth C site, C(17) is bonded in a trigonal planar geometry to one C(14), one C(15), and one C(18) atom. The C(17)-C(18) bond length is 1.52 Å. In the eighteenth C site, C(18) is bonded in a trigonal non-coplanar geometry to one C(17) and three equivalent H(16,17,18) atoms. All C(18)-H(16,17,18) bond lengths are 0.96 Å. There are seven inequivalent H sites. In the first H site, H(1,2,3) is bonded in a single-bond geometry to one C(4) atom. In the second H site, H(4,5,6) is bonded in a single-bond geometry to one C(6) atom. In the third H site, H(7,8,9) is bonded in a single-bond geometry to one C(10) atom. In the fourth H site, H(10,11,12) is bonded in a single-bond geometry to one C(12) atom. In the fifth H site, H(13,14) is bonded in a single-bond geometry to one C(16) atom. In the sixth H site, H(15) is bonded in a single-bond geometry to one C(16) atom. In the seventh H site, H(16,17,18) is bonded in a single-bond geometry to one C(18) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Tm(1) and one C(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one C(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Tm(1) and one C(7) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to two equivalent Tm(1) and one C(7) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Tm(1) and one C(13) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Tm(1) and one C(13) atom. Linkers: 3 Cc1c(C)c(C([O])=O)c(C)c(C)c1C([O])=O. Metal clusters: 1 O=[C]O[Tm]12(O[C]O1)O[C]O[Tm]1(O[C]=O)(O[C]O1)O[C]O2. RCSR code: pcu. The MOF has largest included sphere 6.25 A, density 1.02 g/cm3, surface area 3910.35 m2/g, accessible volume 0.59 cm3/g