Ga15P20(H3O10)8 crystallizes in the trigonal P-3 space group. There are four inequivalent Ga sites. In the first Ga site, Ga(1) is bonded to one O(11), one O(12), one O(5), and one O(9) atom to form GaO4 trigonal pyramids that share  a cornercorner with one P(2)HO3 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, and corners with two equivalent P(3)O4 tetrahedra. The Ga(1)-O(11) bond length is 1.82 Å. The Ga(1)-O(12) bond length is 1.84 Å. The Ga(1)-O(5) bond length is 1.80 Å. The Ga(1)-O(9) bond length is 1.82 Å. In the second Ga site, Ga(2) is bonded to one O(3), one O(4), one O(6), one O(7), and two equivalent O(13) atoms to form GaO6 octahedra that share corners with two equivalent Ga(2)O6 octahedra, corners with two equivalent P(2)HO3 tetrahedra, and corners with two equivalent P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. The Ga(2)-O(3) bond length is 1.99 Å. The Ga(2)-O(4) bond length is 1.99 Å. The Ga(2)-O(6) bond length is 1.92 Å. The Ga(2)-O(7) bond length is 1.92 Å. There is one shorter (1.94 Å) and one longer (1.95 Å) Ga(2)-O(13) bond length. In the third Ga site, Ga(3) is bonded to one O(14) and three equivalent O(10) atoms to form GaO4 trigonal pyramids that share  a cornercorner with one P(4)O4 tetrahedra and corners with three equivalent P(3)O4 tetrahedra. The Ga(3)-O(14) bond length is 1.84 Å. All Ga(3)-O(10) bond lengths are 1.80 Å. In the fourth Ga site, Ga(4) is bonded to six equivalent O(2) atoms to form GaO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. All Ga(4)-O(2) bond lengths are 1.93 Å. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share  a cornercorner with one Ga(4)O6 octahedra and corners with two equivalent Ga(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-50°. The P(1)-O(1) bond length is 1.64 Å. The P(1)-O(2) bond length is 1.50 Å. The P(1)-O(3) bond length is 1.52 Å. The P(1)-O(4) bond length is 1.51 Å. In the second P site, P(2) is bonded to one H(1), one O(12), one O(6), and one O(7) atom to form distorted PHO3 tetrahedra that share corners with two equivalent Ga(2)O6 octahedra and  a cornercorner with one Ga(1)O4 trigonal pyramid. The corner-sharing octahedral tilt angles are 44°. The P(2)-H(1) bond length is 1.33 Å. The P(2)-O(12) bond length is 1.52 Å. The P(2)-O(6) bond length is 1.49 Å. The P(2)-O(7) bond length is 1.49 Å. In the third P site, P(3) is bonded to one O(10), one O(11), one O(8), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Ga(3)O4 trigonal pyramid and corners with two equivalent Ga(1)O4 trigonal pyramids. The P(3)-O(10) bond length is 1.53 Å. The P(3)-O(11) bond length is 1.50 Å. The P(3)-O(8) bond length is 1.50 Å. The P(3)-O(9) bond length is 1.51 Å. In the fourth P site, P(4) is bonded to one O(14) and three equivalent O(5) atoms to form PO4 tetrahedra that share  a cornercorner with one Ga(3)O4 trigonal pyramid and corners with three equivalent Ga(1)O4 trigonal pyramids. The P(4)-O(14) bond length is 1.49 Å. All P(4)-O(5) bond lengths are 1.49 Å. There are four inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one P(2) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(1) atom. The H(2)-O(1) bond length is 0.85 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(1) atom. The H(3)-O(1) bond length is 1.10 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(13) atom. The H(4)-O(13) bond length is 0.85 Å. There are fourteen inequivalent O sites. In the first O site, O(14) is bonded in a linear geometry to one Ga(3) and one P(4) atom. In the second O site, O(1) is bonded in a trigonal planar geometry to one P(1), one H(2), and one H(3) atom. In the third O site, O(2) is bonded in a bent 150 degrees geometry to one Ga(4) and one P(1) atom. In the fourth O site, O(3) is bonded in a bent 120 degrees geometry to one Ga(2) and one P(1) atom. In the fifth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Ga(2) and one P(1) atom. In the sixth O site, O(5) is bonded in a bent 150 degrees geometry to one Ga(1) and one P(4) atom. In the seventh O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Ga(2) and one P(2) atom. In the eighth O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Ga(2) and one P(2) atom. In the ninth O site, O(8) is bonded in a single-bond geometry to one P(3) atom. In the tenth O site, O(9) is bonded in a distorted bent 150 degrees geometry to one Ga(1) and one P(3) atom. In the eleventh O site, O(10) is bonded in a bent 120 degrees geometry to one Ga(3) and one P(3) atom. In the twelfth O site, O(11) is bonded in a bent 150 degrees geometry to one Ga(1) and one P(3) atom. In the thirteenth O site, O(12) is bonded in a bent 150 degrees geometry to one Ga(1) and one P(2) atom. In the fourteenth O site, O(13) is bonded in a distorted single-bond geometry to two equivalent Ga(2) and one H(4) atom. Linkers: 6 O.[O]P([O])[O] ,8 [O]P([O])([O])=O ,6 [O][PH]([O])=O ,6 [OH]. Metal clusters: 15 [Ga]. The MOF has largest included sphere 4.22 A, density 1.88 g/cm3, surface area 2474.31 m2/g, accessible volume 0.25 cm3/g