K2Ca3H4(CO)14 crystallizes in the orthorhombic Pccn space group. K(1) is bonded in a 6-coordinate geometry to one H(1), one H(2), one O(3), one O(5), and two equivalent O(7) atoms. The K(1)-H(1) bond length is 2.90 Å. The K(1)-H(2) bond length is 2.84 Å. The K(1)-O(3) bond length is 2.82 Å. The K(1)-O(5) bond length is 2.88 Å. There is one shorter (2.81 Å) and one longer (2.84 Å) K(1)-O(7) bond length. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(6) atoms to form CaO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra and edges with two equivalent Ca(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 60°. The Ca(1)-O(2) bond length is 2.32 Å. The Ca(1)-O(3) bond length is 2.27 Å. The Ca(1)-O(4) bond length is 2.31 Å. The Ca(1)-O(5) bond length is 2.27 Å. There is one shorter (2.51 Å) and one longer (2.54 Å) Ca(1)-O(6) bond length. In the second Ca site, Ca(2) is bonded to two equivalent O(3), two equivalent O(5), and four equivalent O(4) atoms to form distorted CaO8 hexagonal bipyramids that share edges with two equivalent Ca(2)O8 hexagonal bipyramids and edges with four equivalent Ca(1)O6 octahedra. Both Ca(2)-O(3) bond lengths are 2.55 Å. Both Ca(2)-O(5) bond lengths are 2.53 Å. There are two shorter (2.40 Å) and two longer (2.42 Å) Ca(2)-O(4) bond lengths. There are seven inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one C(2), one O(1), and one O(2) atom. The C(1)-C(2) bond length is 1.48 Å. 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 trigonal planar geometry to one C(1), one C(3), and one C(7) atom. The C(2)-C(3) bond length is 1.41 Å. The C(2)-C(7) bond length is 1.39 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to one C(2) and one H(1) atom. The C(3)-H(1) bond length is 0.93 Å. In the fourth C site, C(4) is bonded in a distorted single-bond geometry to one O(3) atom. The C(4)-O(3) bond length is 1.34 Å. In the fifth C site, C(5) is bonded in a distorted single-bond geometry to one O(4) atom. The C(5)-O(4) bond length is 1.35 Å. In the sixth C site, C(6) is bonded in a distorted single-bond geometry to one O(5) atom. The C(6)-O(5) bond length is 1.34 Å. In the seventh C site, C(7) is bonded in a distorted single-bond geometry to one C(2) and one H(2) atom. The C(7)-H(2) bond length is 0.93 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one K(1) and one C(3) atom. In the second H site, H(2) is bonded in a single-bond geometry to one K(1) and one C(7) atom. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one C(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ca(1) and one C(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one K(1), one Ca(1), one Ca(2), and one C(4) atom. In the fourth O site, O(4) is bonded to one Ca(1), two equivalent Ca(2), and one C(5) atom to form a mixture of distorted edge and corner-sharing OCa3C tetrahedra. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one K(1), one Ca(1), one Ca(2), and one C(6) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to two equivalent Ca(1) atoms. In the seventh O site, O(7) is bonded in an L-shaped geometry to two equivalent K(1) atoms. Linkers: 8 [O]C(=O)c1cc([O])c([O])c([O])c1. Metal clusters: 8 [K] ,12 [Ca]. The MOF has largest included sphere 3.82 A, density 1.66 g/cm3, surface area 2299.67 m2/g, accessible volume 0.11 cm3/g