CaH12(C8O5)2 crystallizes in the monoclinic C2/c space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(5), and four equivalent O(1) atoms. Both Ca(1)-O(2) bond lengths are 2.71 Å. Both Ca(1)-O(5) bond lengths are 2.41 Å. There are two shorter (2.38 Å) and two longer (2.51 Å) Ca(1)-O(1) bond lengths. There are eight 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 1.49 Å. The C(1)-O(1) bond length is 1.27 Å. The C(1)-O(2) 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(3), and one C(8) atom. The C(2)-C(3) bond length is 1.40 Å. The C(2)-C(8) bond length is 1.40 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(1) atom. The C(3)-C(4) bond length is 1.40 Å. The C(3)-H(1) bond length is 1.09 Å. In the fourth C site, C(4) is bonded in a trigonal planar geometry to one C(3), one C(5), and one C(6) atom. The C(4)-C(5) bond length is 1.49 Å. The C(4)-C(6) bond length is 1.40 Å. In the fifth C site, C(5) is bonded in a distorted bent 120 degrees geometry to one C(4), one O(3), and one O(4) atom. The C(5)-O(3) bond length is 1.33 Å. The C(5)-O(4) bond length is 1.24 Å. In the sixth C site, C(6) is bonded in a distorted single-bond geometry to one C(4), one C(7), and one H(2) atom. The C(6)-C(7) bond length is 1.40 Å. The C(6)-H(2) 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(7), and one C(8) atom. The C(7)-C(7) bond length is 1.48 Å. The C(7)-C(8) bond length is 1.40 Å. In the eighth C site, C(8) is bonded in a distorted single-bond geometry to one C(2), one C(7), and one H(3) atom. The C(8)-H(3) bond length is 1.09 Å. There are six inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(3) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(6) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(8) atom. In the fourth H site, H(4) is bonded in a distorted linear geometry to one O(2) and one O(3) atom. The H(4)-O(2) bond length is 1.60 Å. The H(4)-O(3) bond length is 1.01 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(5) atom. The H(5)-O(5) bond length is 0.99 Å. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(5) atom. The H(6)-O(5) bond length is 0.99 Å. There are five inequivalent O sites. In the first O site, O(4) is bonded in a single-bond geometry to one C(5) atom. In the second O site, O(5) is bonded in a distorted water-like geometry to one Ca(1), one H(5), and one H(6) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one C(1) atom. In the fourth O site, O(2) is bonded in a 2-coordinate geometry to one Ca(1), one C(1), and one H(4) atom. In the fifth O site, O(3) is bonded in a water-like geometry to one C(5) and one H(4) atom. Linkers: 2 [O]C(=O)c1cc(C(=O)O)cc(-c2cc(C([O])=O)cc(C(=O)O)c2)c1. Metal clusters: 2 [Ca]. RCSR code: sql. The MOF has largest included sphere 1.36 A, density 1.83 g/cm3, surface area 3348.57 m2/g, accessible volume 0.08 cm3/g