CaCdH12(C4O3)4 crystallizes in the tetragonal I-4c2 space group. Ca(1) is bonded in an octahedral geometry to two equivalent O(1), two equivalent O(4), and two equivalent O(6) atoms. Both Ca(1)-O(1) bond lengths are 2.34 Å. Both Ca(1)-O(4) bond lengths are 2.29 Å. Both Ca(1)-O(6) bond lengths are 2.41 Å. Cd(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Cd(1)-O(1) bond lengths are 2.32 Å. Both Cd(1)-O(2) bond lengths are 2.60 Å. Both Cd(1)-O(3) bond lengths are 2.31 Å. Both Cd(1)-O(4) bond lengths are 2.73 Å. There are eight inequivalent C sites. In the first C site, C(3) is bonded in a trigonal planar geometry to one C(1), one C(4), and one C(8) atom. The C(3)-C(1) bond length is 1.49 Å. The C(3)-C(4) bond length is 1.40 Å. The C(3)-C(8) bond length is 1.40 Å. In the second C site, C(4) is bonded in a distorted single-bond geometry to one C(3) and one H(4) atom. The C(4)-H(4) bond length is 1.09 Å. In the third C site, C(5) is bonded in a distorted single-bond geometry to one O(5) atom. The C(5)-O(5) bond length is 1.35 Å. In the fourth C site, C(6) is bonded in a distorted single-bond geometry to one C(7) and one H(5) atom. The C(6)-C(7) bond length is 1.40 Å. The C(6)-H(5) bond length is 1.09 Å. In the fifth C site, C(7) is bonded in a trigonal planar geometry to one C(2), one C(6), and one C(8) atom. The C(7)-C(2) bond length is 1.49 Å. The C(7)-C(8) bond length is 1.40 Å. In the sixth C site, C(8) is bonded in a distorted trigonal planar geometry to one C(3), one C(7), and one H(6) atom. The C(8)-H(6) bond length is 1.09 Å. In the seventh C site, C(2) is bonded in a distorted bent 120 degrees geometry to one C(7), one O(3), and one O(4) atom. The C(2)-O(3) bond length is 1.28 Å. The C(2)-O(4) bond length is 1.27 Å. In the eighth C site, C(1) is bonded in a bent 120 degrees geometry to one C(3), one O(1), and one O(2) atom. The C(1)-O(1) bond length is 1.29 Å. The C(1)-O(2) bond length is 1.26 Å. There are six inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to one O(2) and one O(5) atom. The H(1)-O(2) bond length is 1.62 Å. The H(1)-O(5) bond length is 1.01 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(6) atom. The H(2)-O(6) bond length is 0.97 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(3) and one O(6) atom. The H(3)-O(3) bond length is 1.75 Å. The H(3)-O(6) bond length is 1.00 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(4) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(6) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one C(8) atom. There are six inequivalent O sites. In the first O site, O(3) is bonded in a 3-coordinate geometry to one Cd(1), one C(2), and one H(3) atom. In the second O site, O(4) is bonded in a distorted linear geometry to one Ca(1), one Cd(1), and one C(2) atom. In the third O site, O(5) is bonded in a water-like geometry to one C(5) and one H(1) atom. In the fourth O site, O(6) is bonded in a trigonal non-coplanar geometry to one Ca(1), one H(2), and one H(3) atom. In the fifth O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Cd(1), and one C(1) atom. In the sixth O site, O(2) is bonded in a 3-coordinate geometry to one Cd(1), one C(1), and one H(1) atom. Linkers: 8 [O]C(=O)c1cc(O)cc(C([O])=O)c1. Metal clusters: 4 [Ca] ,4 [Cd]. The MOF has largest included sphere 6.58 A, density 1.31 g/cm3, surface area 3589.73 m2/g, accessible volume 0.41 cm3/g