BaCuH4(CO)10 crystallizes in the trigonal R-3m space group. Ba(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(5), and four equivalent O(4) atoms. Both Ba(1)-O(2) bond lengths are 2.97 Å. Both Ba(1)-O(5) bond lengths are 2.79 Å. There are two shorter (2.84 Å) and two longer (2.88 Å) Ba(1)-O(4) bond lengths. Cu(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Cu(1)-O(1) bond lengths are 1.94 Å. Both Cu(1)-O(2) bond lengths are 1.96 Å. There are eight inequivalent C sites. In the first C site, C(3) is bonded in a single-bond geometry to one C(4) atom. The C(3)-C(4) bond length is 1.53 Å. In the second C site, C(4) is bonded in a tetrahedral geometry to one C(3), one C(5), and two equivalent C(1) atoms. The C(4)-C(5) bond length is 1.55 Å. Both C(4)-C(1) bond lengths are 1.54 Å. In the third C site, C(5) is bonded in a single-bond geometry to one C(4) atom. In the fourth C site, C(6) is bonded in a tetrahedral geometry to one C(7), one C(8), and two equivalent C(2) atoms. The C(6)-C(7) bond length is 1.52 Å. The C(6)-C(8) bond length is 1.54 Å. Both C(6)-C(2) bond lengths are 1.54 Å. In the fifth C site, C(7) is bonded in a single-bond geometry to one C(6) atom. In the sixth C site, C(8) is bonded in a single-bond geometry to one C(6) atom. In the seventh C site, C(1) is bonded in a distorted bent 120 degrees geometry to one C(4), one O(1), and one O(3) atom. The C(1)-O(1) bond length is 1.29 Å. The C(1)-O(3) bond length is 1.23 Å. In the eighth C site, C(2) is bonded in a distorted bent 120 degrees geometry to one C(6), one O(2), and one O(5) atom. The C(2)-O(2) bond length is 1.28 Å. The C(2)-O(5) bond length is 1.24 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(4) atom. The H(1)-O(4) bond length is 0.85 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(4) atom. The H(2)-O(4) bond length is 0.81 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Cu(1) and one C(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one Cu(1), and one C(2) atom. In the third O site, O(3) is bonded in a single-bond geometry to one C(1) atom. In the fourth O site, O(4) is bonded in a water-like geometry to two equivalent Ba(1), one H(1), and one H(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Ba(1) and one C(2) atom. Linkers: 11 [C]C([C])(C([O])=O)C([O])=O. Metal clusters: 6 [Ba] ,6 [Cu]. The MOF has largest included sphere 4.90 A, density 1.73 g/cm3, surface area 3482.14 m2/g, accessible volume 0.27 cm3/g