AlP3H18(C4O3)3 crystallizes in the trigonal R-3 space group. Al(1) is bonded to one O(1), one O(2), one O(4), one O(6), and one O(8) atom to form AlO5 square pyramids that share  a cornercorner with one P(3)CO3 tetrahedra, corners with two equivalent P(1)CO3 tetrahedra, and corners with two equivalent P(2)CO3 tetrahedra. The Al(1)-O(1) bond length is 1.86 Å. The Al(1)-O(2) bond length is 1.88 Å. The Al(1)-O(4) bond length is 1.94 Å. The Al(1)-O(6) bond length is 1.84 Å. The Al(1)-O(8) bond length is 1.85 Å. There are twelve inequivalent C sites. In the first C site, C(1) is bonded in a distorted water-like geometry to one C(6); one P(2); and two equivalent H(2,5) atoms. The C(1)-C(6) bond length is 1.52 Å. The C(1)-P(2) bond length is 1.81 Å. Both C(1)-H(2,5) bond lengths are 0.97 Å. In the second C site, C(2) is bonded in a distorted water-like geometry to one C(4), one P(3), one H(15), and one H(4) atom. The C(2)-C(4) bond length is 1.52 Å. The C(2)-P(3) bond length is 1.80 Å. The C(2)-H(15) bond length is 0.97 Å. The C(2)-H(4) bond length is 0.97 Å. In the third C site, C(3) is bonded in a trigonal planar geometry to one C(10), one C(12), and one C(9) atom. The C(3)-C(10) bond length is 1.53 Å. The C(3)-C(12) bond length is 1.40 Å. The C(3)-C(9) bond length is 1.40 Å. In the fourth C site, C(4) is bonded in a trigonal planar geometry to one C(11), one C(12), and one C(2) atom. The C(4)-C(11) bond length is 1.41 Å. The C(4)-C(12) bond length is 1.41 Å. In the fifth C site, C(5) is bonded in a trigonal non-coplanar geometry to one C(9), one H(1), one H(13), and one H(14) atom. The C(5)-C(9) bond length is 1.51 Å. The C(5)-H(1) bond length is 0.96 Å. The C(5)-H(13) bond length is 0.96 Å. The C(5)-H(14) bond length is 0.96 Å. In the sixth C site, C(6) is bonded in a trigonal planar geometry to one C(1), one C(11), and one C(9) atom. The C(6)-C(11) bond length is 1.41 Å. The C(6)-C(9) bond length is 1.40 Å. In the seventh C site, C(7) is bonded in a trigonal non-coplanar geometry to one C(11) and three equivalent H(3,10,17) atoms. The C(7)-C(11) bond length is 1.51 Å. All C(7)-H(3,10,17) bond lengths are 0.96 Å. In the eighth C site, C(8) is bonded in a trigonal non-coplanar geometry to one C(12) and three equivalent H(7,11,12) atoms. The C(8)-C(12) bond length is 1.52 Å. All C(8)-H(7,11,12) bond lengths are 0.96 Å. In the ninth C site, C(9) is bonded in a trigonal planar geometry to one C(3), one C(5), and one C(6) atom. In the tenth C site, C(10) is bonded in a distorted water-like geometry to one C(3); one P(1); and two equivalent H(8,18) atoms. The C(10)-P(1) bond length is 1.80 Å. Both C(10)-H(8,18) bond lengths are 0.97 Å. In the eleventh C site, C(11) is bonded in a trigonal planar geometry to one C(4), one C(6), and one C(7) atom. In the twelfth C site, C(12) is bonded in a trigonal planar geometry to one C(3), one C(4), and one C(8) atom. There are three inequivalent P sites. In the first P site, P(1) is bonded to one C(10), one O(1), one O(3), and one O(4) atom to form distorted PCO3 tetrahedra that share corners with two equivalent Al(1)O5 square pyramids. The P(1)-O(1) bond length is 1.50 Å. The P(1)-O(3) bond length is 1.56 Å. The P(1)-O(4) bond length is 1.51 Å. In the second P site, P(2) is bonded to one C(1), one O(5), one O(6), and one O(8) atom to form distorted PCO3 tetrahedra that share corners with two equivalent Al(1)O5 square pyramids. The P(2)-O(5) bond length is 1.56 Å. The P(2)-O(6) bond length is 1.49 Å. The P(2)-O(8) bond length is 1.50 Å. In the third P site, P(3) is bonded to one C(2), one O(2), one O(7), and one O(9) atom to form distorted PCO3 tetrahedra that share  a cornercorner with one Al(1)O5 square pyramid. The P(3)-O(2) bond length is 1.49 Å. The P(3)-O(7) bond length is 1.55 Å. The P(3)-O(9) bond length is 1.53 Å. There are twelve inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(5) atom. In the second H site, H(2,5) is bonded in a single-bond geometry to one C(1) atom. In the third H site, H(3,10,17) is bonded in a single-bond geometry to one C(7) 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(6) is bonded in a single-bond geometry to one O(3) atom. The H(6)-O(3) bond length is 0.82 Å. In the sixth H site, H(7,11,12) is bonded in a single-bond geometry to one C(8) atom. In the seventh H site, H(8,18) is bonded in a single-bond geometry to one C(10) atom. In the eighth H site, H(9) is bonded in a single-bond geometry to one O(5) atom. The H(9)-O(5) bond length is 0.82 Å. In the ninth H site, H(13) is bonded in a single-bond geometry to one C(5) atom. In the tenth H site, H(14) is bonded in a single-bond geometry to one C(5) atom. In the eleventh H site, H(15) is bonded in a single-bond geometry to one C(2) atom. In the twelfth H site, H(16) is bonded in a single-bond geometry to one O(7) atom. The H(16)-O(7) bond length is 0.82 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Al(1) and one P(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Al(1) and one P(3) atom. In the third O site, O(3) is bonded in a water-like geometry to one P(1) and one H(6) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Al(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one P(2) and one H(9) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Al(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted water-like geometry to one P(3) and one H(16) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Al(1) and one P(2) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one P(3) atom. Linkers: 6 Cc1c(CP([O])(=O)O)c(C)c(CP([O])(=O)O)c(C)c1CP([O])(=O)O. Metal clusters: 6 [Al]. The MOF has largest included sphere 11.42 A, density 0.95 g/cm3, surface area 3846.63 m2/g, accessible volume 0.59 cm3/g