BaC5NH6O4 crystallizes in the tetragonal P4nc space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to one O(4), one O(5), one O(7), two equivalent O(2), and two equivalent O(6) atoms to form distorted edge-sharing BaO7 pentagonal bipyramids. The Ba(1)-O(4) bond length is 2.63 Å. The Ba(1)-O(5) bond length is 2.93 Å. The Ba(1)-O(7) bond length is 2.77 Å. There is one shorter (2.81 Å) and one longer (2.82 Å) Ba(1)-O(2) bond length. There is one shorter (2.72 Å) and one longer (2.86 Å) Ba(1)-O(6) bond length. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one N(1), one N(2), one O(1), one O(5), two equivalent O(3), and two equivalent O(8) atoms. The Ba(2)-N(1) bond length is 3.00 Å. The Ba(2)-N(2) bond length is 2.97 Å. The Ba(2)-O(1) bond length is 2.72 Å. The Ba(2)-O(5) bond length is 2.77 Å. There is one shorter (2.78 Å) and one longer (2.79 Å) Ba(2)-O(3) bond length. There is one shorter (2.86 Å) and one longer (2.89 Å) Ba(2)-O(8) bond length. There are ten inequivalent C sites. In the first C site, C(1) is bonded in a 3-coordinate geometry to one N(1), one H(1), and one H(2) atom. The C(1)-N(1) bond length is 1.47 Å. The C(1)-H(1) bond length is 0.99 Å. The C(1)-H(2) bond length is 0.87 Å. In the second C site, C(2) is bonded in a 3-coordinate geometry to one C(3), one N(1), one H(3), and one H(4) atom. The C(2)-C(3) bond length is 1.52 Å. The C(2)-N(1) bond length is 1.45 Å. The C(2)-H(3) bond length is 0.99 Å. The C(2)-H(4) bond length is 0.93 Å. In the third C site, C(3) is bonded in a distorted trigonal planar geometry to one C(2), one O(1), and one O(2) atom. The C(3)-O(1) bond length is 1.26 Å. The C(3)-O(2) bond length is 1.24 Å. In the fourth C site, C(4) is bonded in a 3-coordinate geometry to one N(1), one H(5), and one H(6) atom. The C(4)-N(1) bond length is 1.46 Å. The C(4)-H(5) bond length is 0.97 Å. The C(4)-H(6) bond length is 0.90 Å. In the fifth C site, C(5) is bonded in a distorted bent 120 degrees geometry to one O(3) and one O(4) atom. The C(5)-O(3) bond length is 1.25 Å. The C(5)-O(4) bond length is 1.25 Å. In the sixth C site, C(6) is bonded in a 3-coordinate geometry to one N(2), one H(7), and one H(8) atom. The C(6)-N(2) bond length is 1.46 Å. The C(6)-H(7) bond length is 0.96 Å. The C(6)-H(8) bond length is 0.96 Å. In the seventh C site, C(7) is bonded in a 3-coordinate geometry to one N(2), one H(10), and one H(9) atom. The C(7)-N(2) bond length is 1.48 Å. The C(7)-H(10) bond length is 0.90 Å. The C(7)-H(9) bond length is 0.96 Å. In the eighth C site, C(8) is bonded in a distorted bent 120 degrees geometry to one O(5) and one O(6) atom. The C(8)-O(5) bond length is 1.25 Å. The C(8)-O(6) bond length is 1.25 Å. In the ninth C site, C(9) is bonded in a 3-coordinate geometry to one N(2), one H(11), and one H(12) atom. The C(9)-N(2) bond length is 1.47 Å. The C(9)-H(11) bond length is 0.93 Å. The C(9)-H(12) bond length is 1.02 Å. In the tenth C site, C(10) is bonded in a distorted bent 120 degrees geometry to one O(7) and one O(8) atom. The C(10)-O(7) bond length is 1.25 Å. The C(10)-O(8) bond length is 1.25 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded in a trigonal non-coplanar geometry to one Ba(2), one C(1), one C(2), and one C(4) atom. In the second N site, N(2) is bonded in a trigonal non-coplanar geometry to one Ba(2), one C(6), one C(7), and one C(9) atom. There are twelve 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 C(1) atom. 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 C(2) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(4) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one C(4) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one C(6) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one C(6) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one C(7) atom. In the tenth H site, H(10) is bonded in a single-bond geometry to one C(7) atom. In the eleventh H site, H(11) is bonded in a single-bond geometry to one C(9) atom. In the twelfth H site, H(12) is bonded in a single-bond geometry to one C(9) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Ba(2) and one C(3) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Ba(1) and one C(3) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to two equivalent Ba(2) and one C(5) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Ba(1) and one C(5) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), and one C(8) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Ba(1) and one C(8) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Ba(1) and one C(10) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to two equivalent Ba(2) and one C(10) atom. Linkers: 8 [O]C(=O)CN(CCN(CC([O])=O)CC([O])=O)CC([O])=O. Metal clusters: 16 [Ba]. The MOF has largest included sphere 5.35 A, density 2.14 g/cm3, surface area 2696.11 m2/g, accessible volume 0.14 cm3/g