CaC6H6SO6 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded to one O(3), one O(4), one O(6), two equivalent O(2), and two equivalent O(5) atoms to form a mixture of distorted edge and corner-sharing CaO7 pentagonal bipyramids. The Ca(1)-O(3) bond length is 2.40 Å. The Ca(1)-O(4) bond length is 2.34 Å. The Ca(1)-O(6) bond length is 2.32 Å. There is one shorter (2.36 Å) and one longer (2.52 Å) Ca(1)-O(2) bond length. There is one shorter (2.36 Å) and one longer (2.56 Å) Ca(1)-O(5) bond length. There are six inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one H(1), one O(2), and one O(5) atom. The C(1)-H(1) bond length is 1.11 Å. The C(1)-O(2) bond length is 1.27 Å. The C(1)-O(5) bond length is 1.27 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one C(3), one C(6), and one S(1) atom. The C(2)-C(3) bond length is 1.43 Å. The C(2)-C(6) bond length is 1.38 Å. The C(2)-S(1) bond length is 1.78 Å. In the third C site, C(3) is bonded in a trigonal planar geometry to one C(2), one C(3), and one C(5) atom. The C(3)-C(3) bond length is 1.44 Å. The C(3)-C(5) bond length is 1.42 Å. In the fourth C site, C(4) is bonded in a distorted single-bond geometry to one C(5), one C(6), and one H(4) atom. The C(4)-C(5) bond length is 1.38 Å. The C(4)-C(6) bond length is 1.41 Å. The C(4)-H(4) bond length is 1.09 Å. In the fifth C site, C(5) is bonded in a distorted trigonal planar geometry to one C(3), one C(4), and one H(5) atom. The C(5)-H(5) bond length is 1.09 Å. In the sixth C site, C(6) is bonded in a distorted trigonal planar geometry to one C(2), one C(4), and one H(6) atom. The C(6)-H(6) 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(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(4) atom. The H(2)-O(4) bond length is 0.99 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(4) atom. The H(3)-O(4) bond length is 0.99 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(5) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one C(6) atom. S(1) is bonded in a distorted trigonal non-coplanar geometry to one C(2), one O(1), one O(3), and one O(6) atom. The S(1)-O(1) bond length is 1.48 Å. The S(1)-O(3) bond length is 1.47 Å. The S(1)-O(6) bond length is 1.46 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one S(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one C(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ca(1) and one S(1) atom. In the fourth O site, O(4) is bonded in a distorted water-like geometry to one Ca(1), one H(2), and one H(3) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one C(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Ca(1) and one S(1) atom. Linkers: 2 [O]S([O])([O])c1cccc2c(S([O])([O])[O])cccc12. Metal clusters: 4 [Ca]. The MOF has largest included sphere 1.94 A, density 1.84 g/cm3, surface area 3701.62 m2/g, accessible volume 0.09 cm3/g