Gd3P4H8(CO3)8 crystallizes in the orthorhombic Pbcn space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(12), one O(3), one O(4), one O(5), and one O(6) atom. The Gd(1)-O(1) bond length is 2.34 Å. The Gd(1)-O(10) bond length is 2.59 Å. The Gd(1)-O(12) bond length is 2.37 Å. The Gd(1)-O(3) bond length is 2.27 Å. The Gd(1)-O(4) bond length is 2.51 Å. The Gd(1)-O(5) bond length is 2.54 Å. The Gd(1)-O(6) bond length is 2.48 Å. In the second Gd site, Gd(2) is bonded in a 4-coordinate geometry to two equivalent O(11) and two equivalent O(7) atoms. Both Gd(2)-O(11) bond lengths are 2.40 Å. Both Gd(2)-O(7) bond lengths are 2.35 Å. There are four inequivalent C sites. In the first C site, C(1) is bonded in a 2-coordinate geometry to one C(2), one P(1), one H(1), and one O(4) atom. The C(1)-C(2) bond length is 1.53 Å. The C(1)-P(1) bond length is 1.83 Å. The C(1)-H(1) bond length is 1.00 Å. The C(1)-O(4) bond length is 1.42 Å. In the second C site, C(2) is bonded in a distorted trigonal planar geometry to one C(1), one O(5), and one O(6) atom. The C(2)-O(5) bond length is 1.26 Å. The C(2)-O(6) bond length is 1.26 Å. In the third C site, C(3) is bonded in a 2-coordinate geometry to one P(2), one H(3), and one O(10) atom. The C(3)-P(2) bond length is 1.84 Å. The C(3)-H(3) bond length is 1.00 Å. The C(3)-O(10) bond length is 1.44 Å. In the fourth C site, C(4) is bonded in a distorted bent 120 degrees geometry to one O(11) and one O(12) atom. The C(4)-O(11) bond length is 1.24 Å. The C(4)-O(12) bond length is 1.26 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded in a 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 1.50 Å. The P(1)-O(2) bond length is 1.56 Å. The P(1)-O(3) bond length is 1.49 Å. In the second P site, P(2) is bonded in a tetrahedral geometry to one C(3), one O(7), one O(8), and one O(9) atom. The P(2)-O(7) bond length is 1.52 Å. The P(2)-O(8) bond length is 1.55 Å. The P(2)-O(9) bond length is 1.52 Å. 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 O(4) atom. The H(2)-O(4) bond length is 0.81 Å. In the third H site, H(3) is bonded in a single-bond geometry to one C(3) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(10) atom. The H(4)-O(10) bond length is 0.83 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Gd(1) and one P(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one P(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Gd(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Gd(1), one C(1), and one H(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Gd(1) and one C(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Gd(1) and one C(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Gd(2) and one P(2) atom. In the eighth O site, O(8) is bonded in a single-bond geometry to one P(2) atom. In the ninth O site, O(9) is bonded in a single-bond geometry to one P(2) atom. In the tenth O site, O(10) is bonded in a 1-coordinate geometry to one Gd(1), one C(3), and one H(4) atom. In the eleventh O site, O(11) is bonded in a distorted bent 150 degrees geometry to one Gd(2) and one C(4) atom. In the twelfth O site, O(12) is bonded in a distorted bent 120 degrees geometry to one Gd(1) and one C(4) atom. Linkers: 8 [O]C(=O)[C@H](O)P([O])([O])=O ,8 [O]C(=O)[C@@H](O)P([O])([O])=O. Metal clusters: 12 [Gd]. The MOF has largest included sphere 6.21 A, density 1.94 g/cm3, surface area 2327.94 m2/g, accessible volume 0.24 cm3/g