MnH4(C2O)4 crystallizes in the monoclinic C2/c space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 6-coordinate geometry to one O(2), one O(4), one O(5), one O(6), and two equivalent O(1) atoms. The Mn(1)-O(2) bond length is 2.39 Å. The Mn(1)-O(4) bond length is 2.09 Å. The Mn(1)-O(5) bond length is 2.56 Å. The Mn(1)-O(6) bond length is 2.19 Å. There is one shorter (2.17 Å) and one longer (2.31 Å) Mn(1)-O(1) bond length. In the second Mn site, Mn(2) is bonded in an octahedral geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. Both Mn(2)-O(2) bond lengths are 2.27 Å. Both Mn(2)-O(3) bond lengths are 2.12 Å. Both Mn(2)-O(5) bond lengths are 2.17 Å. There are twelve inequivalent C sites. In the first C site, C(1) is bonded in a bent 120 degrees geometry to one C(2), one O(1), and one O(2) atom. The C(1)-C(2) bond length is 1.49 Å. The C(1)-O(1) bond length is 1.26 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 1.39 Å. The C(2)-C(7) bond length is 1.38 Å. In the third C site, C(3) is bonded in a distorted trigonal planar geometry to one C(2), one C(4), and one H(1) atom. The C(3)-C(4) bond length is 1.39 Å. 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 C(3), one C(5), and one H(2) atom. The C(4)-C(5) bond length is 1.38 Å. The C(4)-H(2) bond length is 0.93 Å. In the fifth C site, C(5) is bonded in a trigonal planar geometry to one C(4), one C(6), and one C(8) atom. The C(5)-C(6) bond length is 1.39 Å. The C(5)-C(8) bond length is 1.51 Å. In the sixth C site, C(6) is bonded in a distorted single-bond geometry to one C(5) and one H(3) atom. The C(6)-H(3) bond length is 0.93 Å. In the seventh C site, C(7) is bonded in a single-bond geometry to one C(2) and one H(4) atom. The C(7)-H(4) bond length is 0.93 Å. In the eighth C site, C(8) is bonded in a distorted bent 120 degrees geometry to one C(5), one O(3), and one O(4) atom. The C(8)-O(3) bond length is 1.26 Å. The C(8)-O(4) bond length is 1.25 Å. In the ninth C site, C(9) is bonded in a distorted bent 120 degrees geometry to one C(10), one O(5), and one O(6) atom. The C(9)-C(10) bond length is 1.50 Å. The C(9)-O(5) bond length is 1.26 Å. The C(9)-O(6) bond length is 1.25 Å. In the tenth C site, C(10) is bonded in a trigonal planar geometry to one C(11), one C(12), and one C(9) atom. The C(10)-C(11) bond length is 1.38 Å. The C(10)-C(12) bond length is 1.39 Å. In the eleventh C site, C(11) is bonded in a distorted single-bond geometry to one C(10) and one H(5) atom. The C(11)-H(5) bond length is 0.93 Å. In the twelfth C site, C(12) is bonded in a distorted single-bond geometry to one C(10) and one H(6) atom. The C(12)-H(6) bond length is 0.93 Å. There are six inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(3) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(4) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(6) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(7) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(11) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one C(12) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to two equivalent Mn(1) and one C(1) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mn(1), one Mn(2), and one C(1) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Mn(2) and one C(8) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Mn(1) and one C(8) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Mn(1), one Mn(2), and one C(9) atom. In the sixth O site, O(6) is bonded in a water-like geometry to one Mn(1) and one C(9) atom. Linkers: 6 [O]C(=O)c1ccc(C([O])=O)cc1. Metal clusters: 6 [Mn]. The MOF has largest included sphere 5.98 A, density 1.23 g/cm3, surface area 3472.13 m2/g, accessible volume 0.40 cm3/g