CaC8H2(O2Br)2 crystallizes in the triclinic P-1 space group. Ca(1) is bonded in a 6-coordinate geometry to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms. The Ca(1)-O(2) bond length is 2.46 Å. The Ca(1)-O(4) bond length is 2.45 Å. There is one shorter (2.36 Å) and one longer (2.59 Å) Ca(1)-O(1) bond length. There is one shorter (2.37 Å) and one longer (2.66 Å) Ca(1)-O(3) bond length. There are eight inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one C(2), one C(4), and one Br(1) atom. The C(1)-C(2) bond length is 1.37 Å. The C(1)-C(4) bond length is 1.39 Å. The C(1)-Br(1) bond length is 1.89 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(4) atom. The C(2)-C(3) bond length is 1.51 Å. The C(2)-C(4) bond length is 1.39 Å. In the third C site, C(3) is bonded in a distorted bent 120 degrees geometry to one C(2), one O(1), and one O(2) atom. The C(3)-O(1) bond length is 1.25 Å. The C(3)-O(2) bond length is 1.25 Å. In the fourth C site, C(4) is bonded in a distorted single-bond geometry to one C(1), one C(2), and one H(1) atom. The C(4)-H(1) bond length is 0.93 Å. In the fifth C site, C(5) is bonded in a trigonal planar geometry to one C(6), one C(7), and one C(8) atom. The C(5)-C(6) bond length is 1.40 Å. The C(5)-C(7) bond length is 1.51 Å. The C(5)-C(8) bond length is 1.38 Å. In the sixth C site, C(6) is bonded in a distorted single-bond geometry to one C(5), one C(8), and one H(2) atom. The C(6)-C(8) bond length is 1.38 Å. The C(6)-H(2) bond length is 0.93 Å. In the seventh C site, C(7) is bonded in a distorted bent 120 degrees geometry to one C(5), one O(3), and one O(4) atom. The C(7)-O(3) bond length is 1.26 Å. The C(7)-O(4) bond length is 1.24 Å. In the eighth C site, C(8) is bonded in a trigonal planar geometry to one C(5), one C(6), and one Br(2) atom. The C(8)-Br(2) bond length is 1.90 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(4) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(6) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one C(3) atom. In the second O site, O(2) is bonded in a distorted L-shaped geometry to one Ca(1) and one C(3) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one C(7) atom. In the fourth O site, O(4) is bonded in a distorted L-shaped geometry to one Ca(1) and one C(7) atom. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded in a single-bond geometry to one C(1) atom. In the second Br site, Br(2) is bonded in a single-bond geometry to one C(8) atom. Linkers: 2 [O]C(=O)c1cc(Br)c(C([O])=O)cc1Br. Metal clusters: 2 [Ca]. The MOF has largest included sphere 4.57 A, density 1.52 g/cm3, surface area 3111.90 m2/g, accessible volume 0.28 cm3/g