ErC12H13(SO7)2 crystallizes in the monoclinic P2_1/m space group. Er(1) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(3), two equivalent O(7), and two equivalent O(9) atoms. The Er(1)-O(1) bond length is 2.21 Å. The Er(1)-O(10) bond length is 2.32 Å. The Er(1)-O(11) bond length is 2.35 Å. The Er(1)-O(3) bond length is 2.33 Å. Both Er(1)-O(7) bond lengths are 2.28 Å. Both Er(1)-O(9) bond lengths are 2.44 Å. There are twelve inequivalent C sites. In the first C site, C(1) is bonded in a distorted trigonal planar geometry to one C(10), one C(2), and one H(6) atom. The C(1)-C(10) bond length is 1.42 Å. The C(1)-C(2) bond length is 1.38 Å. The C(1)-H(6) bond length is 1.09 Å. In the second C site, C(2) is bonded in a trigonal planar geometry to one C(1), one C(11), and one C(3) atom. The C(2)-C(11) bond length is 1.50 Å. The C(2)-C(3) bond length is 1.42 Å. In the third C site, C(3) is bonded in a distorted trigonal planar geometry to one C(2), one C(4), and one H(7) atom. The C(3)-C(4) bond length is 1.37 Å. The C(3)-H(7) bond length is 1.09 Å. In the fourth C site, C(4) is bonded in a trigonal planar geometry to one C(3), one C(9), and one S(1) atom. The C(4)-C(9) bond length is 1.43 Å. The C(4)-S(1) bond length is 1.79 Å. In the fifth C site, C(5) is bonded in a distorted single-bond geometry to one C(6), one C(9), and one H(8) atom. The C(5)-C(6) bond length is 1.39 Å. The C(5)-C(9) bond length is 1.41 Å. The C(5)-H(8) bond length is 1.09 Å. In the sixth C site, C(6) is bonded in a trigonal planar geometry to one C(12), one C(5), and one C(7) atom. The C(6)-C(12) bond length is 1.49 Å. The C(6)-C(7) bond length is 1.41 Å. In the seventh C site, C(7) is bonded in a distorted single-bond geometry to one C(6), one C(8), and one H(9) atom. The C(7)-C(8) bond length is 1.38 Å. The C(7)-H(9) bond length is 1.09 Å. In the eighth C site, C(8) is bonded in a trigonal planar geometry to one C(10), one C(7), and one S(2) atom. The C(8)-C(10) bond length is 1.43 Å. The C(8)-S(2) bond length is 1.78 Å. In the ninth C site, C(9) is bonded in a trigonal planar geometry to one C(10), one C(4), and one C(5) atom. The C(9)-C(10) bond length is 1.44 Å. In the tenth C site, C(10) is bonded in a trigonal planar geometry to one C(1), one C(8), and one C(9) atom. In the eleventh C site, C(11) is bonded in a distorted bent 120 degrees geometry to one C(2), one O(1), and one O(2) atom. The C(11)-O(1) bond length is 1.28 Å. The C(11)-O(2) bond length is 1.27 Å. In the twelfth C site, C(12) is bonded in a distorted bent 120 degrees geometry to one C(6), one O(3), and one O(4) atom. The C(12)-O(3) bond length is 1.24 Å. The C(12)-O(4) bond length is 1.31 Å. There are nine inequivalent H sites. In the first H site, H(1) is bonded in a linear geometry to one O(2) and one O(4) atom. The H(1)-O(2) bond length is 1.50 Å. The H(1)-O(4) bond length is 1.06 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(9) atom. The H(2)-O(9) bond length is 0.99 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(9) atom. The H(3)-O(9) bond length is 0.97 Å. In the fourth H site, H(4) is bonded in a distorted linear geometry to one O(10) and one O(6) atom. The H(4)-O(10) bond length is 1.00 Å. The H(4)-O(6) bond length is 1.66 Å. In the fifth H site, H(5) is bonded in a single-bond geometry to one O(11) atom. The H(5)-O(11) bond length is 0.98 Å. In the sixth H site, H(6) is bonded in a single-bond geometry to one C(1) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one C(3) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one C(5) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one C(7) atom. There are two inequivalent S sites. In the first S site, S(1) is bonded in a distorted trigonal non-coplanar geometry to one C(4), one O(5), and two equivalent O(6) atoms. The S(1)-O(5) bond length is 1.48 Å. Both S(1)-O(6) bond lengths are 1.47 Å. In the second S site, S(2) is bonded in a distorted trigonal non-coplanar geometry to one C(8), one O(8), and two equivalent O(7) atoms. The S(2)-O(8) bond length is 1.44 Å. Both S(2)-O(7) bond lengths are 1.48 Å. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Er(1) and one C(11) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one C(11) and one H(1) atom. In the third O site, O(3) is bonded in a distorted linear geometry to one Er(1) and one C(12) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one C(12) and one H(1) atom. In the fifth O site, O(5) is bonded in a single-bond geometry to one S(1) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one H(4) and one S(1) atom. In the seventh O site, O(7) is bonded in a distorted linear geometry to one Er(1) and one S(2) atom. In the eighth O site, O(8) is bonded in a single-bond geometry to one S(2) atom. In the ninth O site, O(9) is bonded in a water-like geometry to one Er(1), one H(2), and one H(3) atom. In the tenth O site, O(10) is bonded in a distorted water-like geometry to one Er(1) and two equivalent H(4) atoms. In the eleventh O site, O(11) is bonded in a water-like geometry to one Er(1) and two equivalent H(5) atoms. Linkers: 2 [O]C(=O)c1cc(S([O])([O])[O])c2cc(C(=O)O)cc(S([O])([O])[O])c2c1. Metal clusters: 2 [Er]. The MOF has largest included sphere 2.29 A, density 2.41 g/cm3, surface area 2757.65 m2/g, accessible volume 0.06 cm3/g