MnH6(CO3)2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in an octahedral geometry to two equivalent O(1), two equivalent O(3), and two equivalent O(6) atoms. Both Mn(1)-O(1) bond lengths are 2.20 Å. Both Mn(1)-O(3) bond lengths are 2.16 Å. Both Mn(1)-O(6) bond lengths are 2.19 Å. In the second Mn site, Mn(2) is bonded in an octahedral geometry to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. Both Mn(2)-O(2) bond lengths are 2.19 Å. Both Mn(2)-O(4) bond lengths are 2.15 Å. Both Mn(2)-O(5) bond lengths are 2.28 Å. There are two inequivalent C sites. In the first C site, C(2) is bonded in a trigonal planar geometry to one H(3), one O(5), and one O(6) atom. The C(2)-H(3) bond length is 1.11 Å. The C(2)-O(5) bond length is 1.27 Å. The C(2)-O(6) bond length is 1.28 Å. In the second C site, C(1) is bonded in a trigonal planar geometry to one H(1), one O(1), and one O(3) atom. The C(1)-H(1) bond length is 1.10 Å. The C(1)-O(1) bond length is 1.27 Å. The C(1)-O(3) bond length is 1.27 Å. There are six inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(2) and one O(6) atom. The H(2)-O(2) bond length is 1.00 Å. The H(2)-O(6) bond length is 1.71 Å. In the third H site, H(3) is bonded in a single-bond geometry to one C(2) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(2) and one O(3) atom. The H(4)-O(2) bond length is 1.00 Å. The H(4)-O(3) bond length is 1.73 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(1) and one O(4) atom. The H(5)-O(1) bond length is 1.75 Å. The H(5)-O(4) bond length is 0.99 Å. In the sixth H site, H(6) is bonded in a distorted single-bond geometry to one O(4) and one O(5) atom. The H(6)-O(4) bond length is 1.00 Å. The H(6)-O(5) bond length is 1.68 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mn(1), one C(1), and one H(5) atom. In the second O site, O(2) is bonded in a distorted water-like geometry to one Mn(2), one H(2), and one H(4) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mn(1), one C(1), and one H(4) atom. In the fourth O site, O(4) is bonded in a distorted water-like geometry to one Mn(2), one H(5), and one H(6) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mn(2), one C(2), and one H(6) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Mn(1), one C(2), and one H(2) atom. Linkers: 8 [O]C=O. Metal clusters: 4 [Mn]. The MOF has largest included sphere 1.61 A, density 2.03 g/cm3, surface area 3451.14 m2/g, accessible volume 0.10 cm3/g