BaCoH10(CO)10 crystallizes in the trigonal R-3m space group. Ba(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(5) atoms. Both Ba(1)-O(1) bond lengths are 2.81 Å. Both Ba(1)-O(2) bond lengths are 2.92 Å. There are two shorter (2.84 Å) and two longer (2.88 Å) Ba(1)-O(5) bond lengths. Co(1) is bonded in a square co-planar geometry to two equivalent O(2) and two equivalent O(3) atoms. Both Co(1)-O(2) bond lengths are 2.04 Å. Both Co(1)-O(3) bond lengths are 2.01 Å. There are eight inequivalent C sites. In the first C site, C(1) is bonded in a distorted L-shaped geometry to one C(7) and two equivalent H(5) atoms. The C(1)-C(7) bond length is 1.52 Å. Both C(1)-H(5) bond lengths are 0.98 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one C(8), one O(1), and one O(2) atom. The C(2)-C(8) bond length is 1.55 Å. The C(2)-O(1) bond length is 1.23 Å. The C(2)-O(2) bond length is 1.27 Å. In the third C site, C(3) is bonded in a distorted L-shaped geometry to one C(7) and two equivalent H(3) atoms. The C(3)-C(7) bond length is 1.54 Å. Both C(3)-H(3) bond lengths are 0.98 Å. In the fourth C site, C(4) is bonded in a single-bond geometry to one C(8) atom. The C(4)-C(8) bond length is 1.53 Å. In the fifth C site, C(5) is bonded in a distorted bent 120 degrees geometry to one C(8) and two equivalent H(1) atoms. The C(5)-C(8) bond length is 1.54 Å. Both C(5)-H(1) bond lengths are 0.98 Å. In the sixth C site, C(6) is bonded in a distorted bent 120 degrees geometry to one C(7), one O(3), and one O(4) atom. The C(6)-C(7) bond length is 1.58 Å. The C(6)-O(3) bond length is 1.28 Å. The C(6)-O(4) bond length is 1.22 Å. In the seventh C site, C(7) is bonded in a tetrahedral geometry to one C(1), one C(3), and two equivalent C(6) atoms. In the eighth C site, C(8) is bonded in a tetrahedral geometry to one C(4), one C(5), and two equivalent C(2) atoms. There are five inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(5) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(5) atom. The H(2)-O(5) bond length is 0.81 Å. In the third H site, H(3) is bonded in a single-bond geometry to one C(3) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(5) atom. The H(4)-O(5) bond length is 0.82 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(1) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Ba(1) and one C(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ba(1), one Co(1), and one C(2) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Co(1) and one C(6) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one C(6) atom. In the fifth O site, O(5) is bonded in a water-like geometry to two equivalent Ba(1), one H(2), and one H(4) atom. Linkers: 6 [C]C([CH2])(C([O])=O)C([O])=O ,4 [CH2]C([CH2])(C([O])=O)C([O])=O. Metal clusters: 6 [Ba] ,6 [Co]. The MOF has largest included sphere 4.95 A, density 1.73 g/cm3, surface area 3530.56 m2/g, accessible volume 0.24 cm3/g