Ba2CaMo12P8(HO5)10 crystallizes in the monoclinic P2_1/c space group. Ba(1) is bonded in a 7-coordinate geometry to one O(16), one O(18), one O(19), one O(20), one O(21), one O(23), and one O(25) atom. The Ba(1)-O(16) bond length is 2.71 Å. The Ba(1)-O(18) bond length is 2.96 Å. The Ba(1)-O(19) bond length is 2.72 Å. The Ba(1)-O(20) bond length is 2.86 Å. The Ba(1)-O(21) bond length is 3.08 Å. The Ba(1)-O(23) bond length is 2.73 Å. The Ba(1)-O(25) bond length is 2.78 Å. Ca(1) is bonded to two equivalent O(10), two equivalent O(17), and two equivalent O(2) atoms to form CaO6 octahedra that share corners with two equivalent Mo(3)O5 square pyramids, corners with two equivalent Mo(4)O5 square pyramids, and corners with two equivalent Mo(6)O5 square pyramids. Both Ca(1)-O(10) bond lengths are 2.33 Å. Both Ca(1)-O(17) bond lengths are 2.31 Å. Both Ca(1)-O(2) bond lengths are 2.28 Å. There are six inequivalent Mo sites. In the first Mo site, Mo(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(5) atom. The Mo(1)-O(1) bond length is 1.93 Å. The Mo(1)-O(2) bond length is 1.95 Å. The Mo(1)-O(3) bond length is 2.11 Å. The Mo(1)-O(4) bond length is 2.04 Å. The Mo(1)-O(5) bond length is 2.27 Å. In the second Mo site, Mo(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(6), one O(7), and one O(8) atom. The Mo(2)-O(1) bond length is 1.94 Å. The Mo(2)-O(2) bond length is 1.95 Å. The Mo(2)-O(6) bond length is 2.06 Å. The Mo(2)-O(7) bond length is 2.12 Å. The Mo(2)-O(8) bond length is 2.27 Å. In the third Mo site, Mo(3) is bonded to one O(10), one O(11), one O(7), one O(8), and one O(9) atom to form distorted MoO5 square pyramids that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, and  an edgeedge with one Mo(4)O5 square pyramid. The corner-sharing octahedral tilt angles are 49°. The Mo(3)-O(10) bond length is 1.95 Å. The Mo(3)-O(11) bond length is 1.94 Å. The Mo(3)-O(7) bond length is 2.10 Å. The Mo(3)-O(8) bond length is 2.31 Å. The Mo(3)-O(9) bond length is 2.08 Å. In the fourth Mo site, Mo(4) is bonded to one O(10), one O(11), one O(12), one O(13), and one O(14) atom to form distorted MoO5 square pyramids that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, and  an edgeedge with one Mo(3)O5 square pyramid. The corner-sharing octahedral tilt angles are 48°. The Mo(4)-O(10) bond length is 1.96 Å. The Mo(4)-O(11) bond length is 1.93 Å. The Mo(4)-O(12) bond length is 2.14 Å. The Mo(4)-O(13) bond length is 2.08 Å. The Mo(4)-O(14) bond length is 2.25 Å. In the fifth Mo site, Mo(5) is bonded in a 5-coordinate geometry to one O(12), one O(14), one O(15), one O(16), and one O(17) atom. The Mo(5)-O(12) bond length is 2.12 Å. The Mo(5)-O(14) bond length is 2.27 Å. The Mo(5)-O(15) bond length is 2.05 Å. The Mo(5)-O(16) bond length is 1.94 Å. The Mo(5)-O(17) bond length is 1.95 Å. In the sixth Mo site, Mo(6) is bonded to one O(16), one O(17), one O(18), one O(3), and one O(5) atom to form distorted MoO5 square pyramids that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one P(3)O4 tetrahedra, and  a cornercorner with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. The Mo(6)-O(16) bond length is 1.95 Å. The Mo(6)-O(17) bond length is 1.95 Å. The Mo(6)-O(18) bond length is 2.09 Å. The Mo(6)-O(3) bond length is 2.11 Å. The Mo(6)-O(5) bond length is 2.24 Å. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(19), one O(20), one O(6), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Mo(3)O5 square pyramid. The P(1)-O(19) bond length is 1.55 Å. The P(1)-O(20) bond length is 1.51 Å. The P(1)-O(6) bond length is 1.53 Å. The P(1)-O(9) bond length is 1.53 Å. In the second P site, P(2) is bonded to one O(13), one O(15), one O(21), and one O(22) atom to form PO4 tetrahedra that share  a cornercorner with one Mo(4)O5 square pyramid. The P(2)-O(13) bond length is 1.53 Å. The P(2)-O(15) bond length is 1.56 Å. The P(2)-O(21) bond length is 1.50 Å. The P(2)-O(22) bond length is 1.53 Å. In the third P site, P(3) is bonded to one O(18), one O(23), one O(24), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one Mo(6)O5 square pyramid. The P(3)-O(18) bond length is 1.54 Å. The P(3)-O(23) bond length is 1.53 Å. The P(3)-O(24) bond length is 1.51 Å. The P(3)-O(4) bond length is 1.54 Å. In the fourth P site, P(4) is bonded to one O(14), one O(25), one O(5), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Mo(3)O5 square pyramid,  a cornercorner with one Mo(4)O5 square pyramid, and  a cornercorner with one Mo(6)O5 square pyramid. The P(4)-O(14) bond length is 1.55 Å. The P(4)-O(25) bond length is 1.48 Å. The P(4)-O(5) bond length is 1.56 Å. The P(4)-O(8) bond length is 1.56 Å. There are five inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(3) atom. The H(1)-O(3) bond length is 0.85 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(7) atom. The H(2)-O(7) bond length is 0.85 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(12) atom. The H(3)-O(12) bond length is 0.85 Å. In the fourth H site, H(4) is bonded in a linear geometry to one O(19) and one O(22) atom. The H(4)-O(19) bond length is 1.57 Å. The H(4)-O(22) bond length is 0.85 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(24) atom. The H(5)-O(24) bond length is 0.85 Å. There are twenty-five inequivalent O sites. In the first O site, O(1) is bonded in an L-shaped geometry to one Mo(1) and one Mo(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ca(1), one Mo(1), and one Mo(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Mo(1), one Mo(6), and one H(1) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one Mo(1) and one P(3) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Mo(1), one Mo(6), and one P(4) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Mo(2) and one P(1) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Mo(2), one Mo(3), and one H(2) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one Mo(2), one Mo(3), and one P(4) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one Mo(3) and one P(1) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Ca(1), one Mo(3), and one Mo(4) atom. In the eleventh O site, O(11) is bonded in an L-shaped geometry to one Mo(3) and one Mo(4) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal non-coplanar geometry to one Mo(4), one Mo(5), and one H(3) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one Mo(4) and one P(2) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one Mo(4), one Mo(5), and one P(4) atom. In the fifteenth O site, O(15) is bonded in a distorted single-bond geometry to one Mo(5) and one P(2) atom. In the sixteenth O site, O(16) is bonded in a 3-coordinate geometry to one Ba(1), one Mo(5), and one Mo(6) atom. In the seventeenth O site, O(17) is bonded in a distorted T-shaped geometry to one Ca(1), one Mo(5), and one Mo(6) atom. In the eighteenth O site, O(18) is bonded in a distorted single-bond geometry to one Ba(1), one Mo(6), and one P(3) atom. In the nineteenth O site, O(19) is bonded in a 3-coordinate geometry to one Ba(1), one P(1), and one H(4) atom. In the twentieth O site, O(20) is bonded in a single-bond geometry to one Ba(1) and one P(1) atom. In the twenty-first O site, O(21) is bonded in a single-bond geometry to one Ba(1) and one P(2) atom. In the twenty-second O site, O(22) is bonded in a water-like geometry to one P(2) and one H(4) atom. In the twenty-third O site, O(23) is bonded in a distorted single-bond geometry to one Ba(1) and one P(3) atom. In the twenty-fourth O site, O(24) is bonded in a water-like geometry to one P(3) and one H(5) atom. In the twenty-fifth O site, O(25) is bonded in a distorted single-bond geometry to one Ba(1) and one P(4) atom. Linkers: 8 [O]P([O])([O])=O ,8 [O]P([O])(=O)O ,12 [OH]. Metal clusters: 4 [Ba] ,2 [Ca] ,24 [Mo]. The MOF has largest included sphere 6.25 A, density 2.02 g/cm3, surface area 1732.19 m2/g, accessible volume 0.25 cm3/g