KCd(CO2)4 crystallizes in the monoclinic C2/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a distorted hexagonal planar geometry to two equivalent O(3), two equivalent O(4), and two equivalent O(8) atoms. Both K(1)-O(3) bond lengths are 2.71 Å. Both K(1)-O(4) bond lengths are 2.71 Å. Both K(1)-O(8) bond lengths are 2.76 Å. In the second K site, K(2) is bonded in a distorted hexagonal planar geometry to two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms. Both K(2)-O(5) bond lengths are 2.71 Å. Both K(2)-O(6) bond lengths are 2.73 Å. Both K(2)-O(7) bond lengths are 2.76 Å. Cd(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. The Cd(1)-O(1) bond length is 2.33 Å. The Cd(1)-O(2) bond length is 2.36 Å. The Cd(1)-O(3) bond length is 2.36 Å. The Cd(1)-O(4) bond length is 2.42 Å. The Cd(1)-O(5) bond length is 2.42 Å. The Cd(1)-O(6) bond length is 2.46 Å. The Cd(1)-O(7) bond length is 2.50 Å. The Cd(1)-O(8) bond length is 2.53 Å. There are four inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one O(1) and one O(8) atom. The C(1)-O(1) bond length is 1.26 Å. The C(1)-O(8) bond length is 1.25 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one O(2) and one O(7) atom. The C(2)-O(2) bond length is 1.25 Å. The C(2)-O(7) bond length is 1.25 Å. In the third C site, C(3) is bonded in a distorted bent 120 degrees geometry to one O(3) and one O(6) atom. The C(3)-O(3) bond length is 1.25 Å. The C(3)-O(6) bond length is 1.25 Å. In the fourth C site, C(4) is bonded in a distorted bent 120 degrees geometry to one O(4) and one O(5) atom. The C(4)-O(4) bond length is 1.26 Å. The C(4)-O(5) bond length is 1.24 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Cd(1) and one C(1) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Cd(1) and one C(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one K(1), one Cd(1), and one C(3) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one K(1), one Cd(1), and one C(4) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one K(2), one Cd(1), and one C(4) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one K(2), one Cd(1), and one C(3) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one K(2), one Cd(1), and one C(2) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(1), one Cd(1), and one C(1) atom. Linkers: 16 [O]C(=O)C([O])=O. Metal clusters: 8 [K] ,8 [Cd]. The MOF has largest included sphere 4.43 A, density 1.95 g/cm3, surface area 2223.72 m2/g, accessible volume 0.13 cm3/g