HoH15(C2O)9 crystallizes in the triclinic P-1 space group. Ho(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(6), one O(7), one O(8), and one O(9) atom. The Ho(1)-O(1) bond length is 2.36 Å. The Ho(1)-O(2) bond length is 2.46 Å. The Ho(1)-O(3) bond length is 2.36 Å. The Ho(1)-O(4) bond length is 2.27 Å. The Ho(1)-O(6) bond length is 2.24 Å. The Ho(1)-O(7) bond length is 2.28 Å. The Ho(1)-O(8) bond length is 2.40 Å. The Ho(1)-O(9) bond length is 2.47 Å. 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(4), and one O(5) atom. The C(1)-C(2) bond length is 1.49 Å. The C(1)-O(4) bond length is 1.27 Å. The C(1)-O(5) bond length is 1.28 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one C(1), one C(12), and one C(3) atom. The C(2)-C(12) bond length is 1.39 Å. The C(2)-C(3) bond length is 1.42 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to one C(2), one C(4), and one H(7) atom. The C(3)-C(4) bond length is 1.37 Å. The C(3)-H(7) bond length is 1.09 Å. In the fourth C site, C(4) is bonded in a distorted trigonal planar geometry to one C(3), one C(5), and one H(8) atom. The C(4)-C(5) bond length is 1.42 Å. The C(4)-H(8) bond length is 1.09 Å. In the fifth C site, C(5) is bonded in a trigonal planar geometry to one C(11), one C(4), and one C(6) atom. The C(5)-C(11) bond length is 1.44 Å. The C(5)-C(6) bond length is 1.41 Å. In the sixth C site, C(6) is bonded in a distorted trigonal planar geometry to one C(5), one C(7), and one H(9) atom. The C(6)-C(7) bond length is 1.38 Å. The C(6)-H(9) bond length is 1.09 Å. In the seventh C site, C(7) is bonded in a trigonal planar geometry to one C(6), one C(8), and one C(9) atom. The C(7)-C(8) bond length is 1.50 Å. The C(7)-C(9) bond length is 1.42 Å. In the eighth C site, C(8) is bonded in a distorted bent 120 degrees geometry to one C(7), one O(6), and one O(7) atom. The C(8)-O(6) bond length is 1.28 Å. The C(8)-O(7) bond length is 1.27 Å. In the ninth C site, C(9) is bonded in a distorted single-bond geometry to one C(7) and one H(10) atom. The C(9)-H(10) bond length is 1.09 Å. In the tenth C site, C(10) is bonded in a distorted single-bond geometry to one C(11) and one H(11) atom. The C(10)-C(11) bond length is 1.42 Å. The C(10)-H(11) bond length is 1.09 Å. In the eleventh C site, C(11) is bonded in a trigonal planar geometry to one C(10), one C(12), and one C(5) atom. The C(11)-C(12) bond length is 1.42 Å. In the twelfth C site, C(12) is bonded in a distorted single-bond geometry to one C(11), one C(2), and one H(12) atom. The C(12)-H(12) bond length is 1.09 Å. In the thirteenth C site, C(13) is bonded in a distorted bent 120 degrees geometry to one C(14), one O(8), and one O(9) atom. The C(13)-C(14) bond length is 1.49 Å. The C(13)-O(8) bond length is 1.29 Å. The C(13)-O(9) bond length is 1.28 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(18) atom. The C(14)-C(15) bond length is 1.42 Å. The C(14)-C(18) bond length is 1.39 Å. In the fifteenth C site, C(15) is bonded in a distorted single-bond geometry to one C(14) and one H(13) atom. The C(15)-H(13) bond length is 1.09 Å. In the sixteenth C site, C(16) is bonded in a distorted single-bond geometry to one C(17) and one H(14) atom. The C(16)-C(17) bond length is 1.42 Å. The C(16)-H(14) bond length is 1.09 Å. In the seventeenth C site, C(17) is bonded in a trigonal planar geometry to one C(16), one C(17), and one C(18) atom. The C(17)-C(17) bond length is 1.44 Å. The C(17)-C(18) bond length is 1.41 Å. In the eighteenth C site, C(18) is bonded in a distorted single-bond geometry to one C(14), one C(17), and one H(15) atom. The C(18)-H(15) bond length is 1.09 Å. There are fifteen inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one O(1) atom. The H(1)-O(1) bond length is 1.00 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(1) atom. The H(2)-O(1) bond length is 0.99 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(2) atom. The H(3)-O(2) bond length is 0.99 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(2) atom. The H(4)-O(2) bond length is 0.99 Å. In the fifth H site, H(5) is bonded in a distorted linear geometry to one O(3) and one O(9) atom. The H(5)-O(3) bond length is 1.00 Å. The H(5)-O(9) bond length is 1.64 Å. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(3) atom. The H(6)-O(3) bond length is 0.98 Å. In the seventh H site, H(7) is bonded in a single-bond geometry to one C(3) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one C(4) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one C(6) atom. In the tenth H site, H(10) is bonded in a single-bond geometry to one C(9) atom. In the eleventh H site, H(11) is bonded in a single-bond geometry to one C(10) atom. In the twelfth H site, H(12) is bonded in a single-bond geometry to one C(12) atom. In the thirteenth H site, H(13) is bonded in a single-bond geometry to one C(15) atom. In the fourteenth H site, H(14) is bonded in a single-bond geometry to one C(16) atom. In the fifteenth H site, H(15) is bonded in a single-bond geometry to one C(18) atom. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted water-like geometry to one Ho(1), one H(1), and one H(2) atom. In the second O site, O(2) is bonded in a distorted water-like geometry to one Ho(1), one H(3), and one H(4) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one Ho(1), one H(5), and one H(6) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Ho(1) and one C(1) atom. In the fifth O site, O(5) is bonded in a 1-coordinate geometry to one C(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Ho(1) and one C(8) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Ho(1) and one C(8) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one Ho(1) and one C(13) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Ho(1), one C(13), and one H(5) atom. Linkers: 2 [O]C(=O)c1ccc2cc(C([O])=O)ccc2c1 ,1 [O]C(=O)c1ccc2cc([C]=O)ccc2c1. Metal clusters: 1 O.O.O.O.O.O.O=[C]O[Ho]1(O[C]=O)O[C]O[Ho](O[C]=O)(O[C]=O)O[C]O1. RCSR code: sql. The MOF has largest included sphere 2.07 A, density 2.10 g/cm3, surface area 3181.26 m2/g, accessible volume 0.07 cm3/g