CdH4(CO3)2 crystallizes in the triclinic P1 space group. There are two inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to one O(1), one O(10), one O(3), one O(5), one O(6), one O(8), and one O(9) atom to form edge-sharing CdO7 pentagonal bipyramids. The Cd(1)-O(1) bond length is 2.34 Å. The Cd(1)-O(10) bond length is 2.28 Å. The Cd(1)-O(3) bond length is 2.46 Å. The Cd(1)-O(5) bond length is 2.43 Å. The Cd(1)-O(6) bond length is 2.38 Å. The Cd(1)-O(8) bond length is 2.41 Å. The Cd(1)-O(9) bond length is 2.37 Å. In the second Cd site, Cd(2) is bonded to one O(11), one O(12), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form edge-sharing CdO7 pentagonal bipyramids. The Cd(2)-O(11) bond length is 2.32 Å. The Cd(2)-O(12) bond length is 2.30 Å. The Cd(2)-O(2) bond length is 2.49 Å. The Cd(2)-O(4) bond length is 2.33 Å. The Cd(2)-O(5) bond length is 2.44 Å. The Cd(2)-O(7) bond length is 2.38 Å. The Cd(2)-O(8) bond length is 2.45 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(2) atom. The C(1)-O(1) bond length is 1.28 Å. The C(1)-O(2) bond length is 1.26 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one O(3) and one O(4) atom. The C(2)-O(3) bond length is 1.26 Å. The C(2)-O(4) bond length is 1.27 Å. In the third C site, C(3) is bonded in a distorted bent 120 degrees geometry to one O(5) and one O(6) atom. The C(3)-O(5) bond length is 1.27 Å. The C(3)-O(6) bond length is 1.26 Å. In the fourth C site, C(4) is bonded in a distorted bent 120 degrees geometry to one O(7) and one O(8) atom. The C(4)-O(7) bond length is 1.26 Å. The C(4)-O(8) bond length is 1.27 Å. There are eight inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(9) atom. The H(1)-O(9) bond length is 0.98 Å. In the second H site, H(2) is bonded in a distorted linear geometry to one O(1) and one O(9) atom. The H(2)-O(1) bond length is 1.57 Å. The H(2)-O(9) bond length is 1.02 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(10) atom. The H(3)-O(10) bond length is 0.99 Å. In the fourth H site, H(4) is bonded in a distorted single-bond geometry to one O(10) and one O(2) atom. The H(4)-O(10) bond length is 1.00 Å. The H(4)-O(2) bond length is 1.71 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(11) atom. The H(5)-O(11) bond length is 1.00 Å. In the sixth H site, H(6) is bonded in a single-bond geometry to one O(11) atom. The H(6)-O(11) bond length is 0.99 Å. In the seventh H site, H(7) is bonded in a single-bond geometry to one O(12) atom. The H(7)-O(12) bond length is 0.99 Å. In the eighth H site, H(8) is bonded in a distorted single-bond geometry to one O(12) and one O(4) atom. The H(8)-O(12) bond length is 1.00 Å. The H(8)-O(4) bond length is 1.68 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Cd(1), one C(1), and one H(2) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Cd(2), one C(1), and one H(4) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Cd(1) and one C(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Cd(2), one C(2), and one H(8) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Cd(1), one Cd(2), and one C(3) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to 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 Cd(2) and one C(4) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Cd(1), one Cd(2), and one C(4) atom. In the ninth O site, O(9) is bonded in a distorted water-like geometry to one Cd(1), one H(1), and one H(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Cd(1), one H(3), and one H(4) atom. In the eleventh O site, O(11) is bonded in a distorted water-like geometry to one Cd(2), one H(5), and one H(6) atom. In the twelfth O site, O(12) is bonded in a distorted water-like geometry to one Cd(2), one H(7), and one H(8) atom. Linkers: 2 [O]C(=O)C([O])=O. Metal clusters: 2 [Cd]. The MOF has largest included sphere 3.02 A, density 2.51 g/cm3, surface area 2663.11 m2/g, accessible volume 0.11 cm3/g