KU(CO2)7 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to two equivalent O(10), two equivalent O(2), two equivalent O(7), and two equivalent O(8) atoms. Both K(1)-O(10) bond lengths are 3.13 Å. Both K(1)-O(2) bond lengths are 2.76 Å. Both K(1)-O(7) bond lengths are 2.91 Å. Both K(1)-O(8) bond lengths are 2.72 Å. In the second K site, K(2) is bonded in a distorted body-centered cubic geometry to two equivalent O(4), two equivalent O(7), and four equivalent O(3) atoms. Both K(2)-O(4) bond lengths are 2.89 Å. Both K(2)-O(7) bond lengths are 2.80 Å. There are two shorter (2.81 Å) and two longer (2.91 Å) K(2)-O(3) bond lengths. U(1) is bonded in a 10-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(13), one O(14), one O(2), one O(5), one O(6), and one O(9) atom. The U(1)-O(1) bond length is 2.42 Å. The U(1)-O(10) bond length is 2.54 Å. The U(1)-O(11) bond length is 2.55 Å. The U(1)-O(12) bond length is 2.51 Å. The U(1)-O(13) bond length is 2.48 Å. The U(1)-O(14) bond length is 2.47 Å. The U(1)-O(2) bond length is 2.39 Å. The U(1)-O(5) bond length is 2.40 Å. The U(1)-O(6) bond length is 2.37 Å. The U(1)-O(9) bond length is 2.51 Å. There are nine 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(4) atom. The C(1)-O(1) bond length is 1.27 Å. The C(1)-O(4) bond length is 1.23 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one O(2) and one O(3) atom. The C(2)-O(2) bond length is 1.28 Å. The C(2)-O(3) bond length is 1.24 Å. In the third C site, C(3) is bonded in a distorted bent 120 degrees geometry to one O(6) and one O(8) atom. The C(3)-O(6) bond length is 1.28 Å. The C(3)-O(8) bond length is 1.23 Å. In the fourth C site, C(4) is bonded in a distorted bent 120 degrees geometry to one O(5) and one O(7) atom. The C(4)-O(5) bond length is 1.27 Å. The C(4)-O(7) bond length is 1.24 Å. In the fifth C site, C(5) is bonded in a distorted bent 120 degrees geometry to one O(13) and one O(14) atom. The C(5)-O(13) bond length is 1.25 Å. The C(5)-O(14) bond length is 1.25 Å. In the sixth C site, C(6) is bonded in a distorted bent 120 degrees geometry to two equivalent O(9) atoms. Both C(6)-O(9) bond lengths are 1.25 Å. In the seventh C site, C(7) is bonded in a distorted bent 120 degrees geometry to two equivalent O(10) atoms. Both C(7)-O(10) bond lengths are 1.25 Å. In the eighth C site, C(8) is bonded in a distorted bent 120 degrees geometry to two equivalent O(11) atoms. Both C(8)-O(11) bond lengths are 1.26 Å. In the ninth C site, C(9) is bonded in a distorted bent 120 degrees geometry to two equivalent O(12) atoms. Both C(9)-O(12) bond lengths are 1.25 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one U(1) and one C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), one U(1), and one C(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to two equivalent K(2) and one C(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one K(2) and one C(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one U(1) and one C(4) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one U(1) and one C(3) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one K(1), one K(2), and one C(4) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(1) and one C(3) atom. In the ninth O site, O(9) is bonded in a distorted bent 120 degrees geometry to one U(1) and one C(6) atom. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one K(1), one U(1), and one C(7) atom. In the eleventh O site, O(11) is bonded in a distorted single-bond geometry to one U(1) and one C(8) atom. In the twelfth O site, O(12) is bonded in a distorted bent 120 degrees geometry to one U(1) and one C(9) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 120 degrees geometry to one U(1) and one C(5) atom. In the fourteenth O site, O(14) is bonded in a distorted bent 120 degrees geometry to one U(1) and one C(5) atom. Linkers: 14 [O]C(=O)C([O])=O. Metal clusters: 4 [K] ,4 [U]. The MOF has largest included sphere 5.70 A, density 2.03 g/cm3, surface area 1933.88 m2/g, accessible volume 0.22 cm3/g