Ba3C4P4H8(NO6)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to one O(6), two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. The Ba(1)-O(6) bond length is 3.07 Å. There is one shorter (2.73 Å) and one longer (2.84 Å) Ba(1)-O(1) bond length. There is one shorter (2.84 Å) and one longer (2.97 Å) Ba(1)-O(2) bond length. There is one shorter (2.88 Å) and one longer (2.98 Å) Ba(1)-O(3) bond length. There is one shorter (2.69 Å) and one longer (2.81 Å) Ba(1)-O(4) bond length. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to two equivalent O(6) and four equivalent O(5) atoms. Both Ba(2)-O(6) bond lengths are 2.95 Å. There are two shorter (2.63 Å) and two longer (2.73 Å) Ba(2)-O(5) bond lengths. There are two inequivalent C sites. In the first C site, C(1) is bonded in a 2-coordinate geometry to one P(1), one N(1), one H(1), and one H(2) atom. The C(1)-P(1) bond length is 1.82 Å. The C(1)-N(1) bond length is 1.49 Å. The C(1)-H(1) bond length is 0.81 Å. The C(1)-H(2) bond length is 0.88 Å. In the second C site, C(2) is bonded in a distorted tetrahedral geometry to one P(2), one N(1), one H(3), and one H(4) atom. The C(2)-P(2) bond length is 1.82 Å. The C(2)-N(1) bond length is 1.48 Å. The C(2)-H(3) bond length is 0.98 Å. The C(2)-H(4) bond length is 0.94 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded in a distorted tetrahedral geometry to one C(1), one O(1), one O(2), and one O(3) atom. The P(1)-O(1) bond length is 1.52 Å. The P(1)-O(2) bond length is 1.52 Å. The P(1)-O(3) bond length is 1.53 Å. In the second P site, P(2) is bonded in a distorted tetrahedral geometry to one C(2), one O(4), one O(5), and one O(6) atom. The P(2)-O(4) bond length is 1.51 Å. The P(2)-O(5) bond length is 1.52 Å. The P(2)-O(6) bond length is 1.53 Å. N(1) is bonded in a bent 120 degrees geometry to one C(1) and one C(2) atom. There are four 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. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Ba(1) and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent Ba(1) and one P(1) atom. In the third O site, O(3) is bonded in a single-bond geometry to two equivalent Ba(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to two equivalent Ba(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Ba(2) and one P(2) atom. In the sixth O site, O(6) is bonded in a single-bond geometry to one Ba(1), one Ba(2), and one P(2) atom. Linkers: 4 [O]P([O])(=O)C[N]CP([O])([O])=O. Metal clusters: 6 [Ba]. The MOF has largest included sphere 5.66 A, density 2.40 g/cm3, surface area 2024.69 m2/g, accessible volume 0.18 cm3/g