CaC18H24(NO2)4 crystallizes in the triclinic P-1 space group. Ca(1) is bonded in an octahedral geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. Both Ca(1)-O(1) bond lengths are 2.30 Å. Both Ca(1)-O(2) bond lengths are 2.35 Å. Both Ca(1)-O(4) bond lengths are 2.39 Å. There are nine inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to one C(2), one C(5), and one C(6) atom. The C(1)-C(2) bond length is 1.40 Å. The C(1)-C(5) bond length is 1.40 Å. The C(1)-C(6) bond length is 1.51 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one C(1), one N(1), and one H(3) atom. The C(2)-N(1) bond length is 1.34 Å. The C(2)-H(3) bond length is 1.09 Å. In the third C site, C(3) is bonded in a distorted trigonal planar geometry to one C(3), one C(4), and one N(1) atom. The C(3)-C(3) bond length is 1.49 Å. The C(3)-C(4) bond length is 1.40 Å. The C(3)-N(1) bond length is 1.35 Å. In the fourth C site, C(4) is bonded in a distorted single-bond geometry to one C(3) and one H(4) atom. The C(4)-H(4) bond length is 1.09 Å. In the fifth C site, C(5) is bonded in a distorted single-bond geometry to one C(1) and one H(5) atom. The C(5)-H(5) bond length is 1.09 Å. In the sixth C site, C(6) is bonded in a distorted bent 120 degrees geometry to one C(1), one O(1), and one O(3) atom. The C(6)-O(1) bond length is 1.26 Å. The C(6)-O(3) bond length is 1.27 Å. In the seventh C site, C(7) is bonded in a trigonal planar geometry to one N(2), one H(6), and one O(4) atom. The C(7)-N(2) bond length is 1.34 Å. The C(7)-H(6) bond length is 1.10 Å. The C(7)-O(4) bond length is 1.25 Å. In the eighth C site, C(8) is bonded to one N(2), one H(7), one H(8), and one H(9) atom to form corner-sharing CH3N tetrahedra. The C(8)-N(2) bond length is 1.45 Å. The C(8)-H(7) bond length is 1.09 Å. The C(8)-H(8) bond length is 1.10 Å. The C(8)-H(9) bond length is 1.10 Å. In the ninth C site, C(9) is bonded to one N(2), one H(10), one H(11), and one H(12) atom to form corner-sharing CH3N tetrahedra. The C(9)-N(2) bond length is 1.45 Å. The C(9)-H(10) bond length is 1.10 Å. The C(9)-H(11) bond length is 1.10 Å. The C(9)-H(12) bond length is 1.10 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded in a bent 120 degrees geometry to one C(2) and one C(3) atom. In the second N site, N(2) is bonded in a trigonal planar geometry to one C(7), one C(8), and one C(9) atom. There are twelve inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one O(2) and one O(3) atom. The H(1)-O(2) bond length is 1.00 Å. The H(1)-O(3) bond length is 1.64 Å. In the second H site, H(2) is bonded in a distorted single-bond geometry to one O(2) and one O(3) atom. The H(2)-O(2) bond length is 1.00 Å. The H(2)-O(3) bond length is 1.67 Å. In the third H site, H(3) is bonded in a single-bond geometry to one C(2) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(4) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(5) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one C(7) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one C(8) atom. In the eighth H site, H(8) is bonded in a single-bond geometry to one C(8) atom. In the ninth H site, H(9) is bonded in a single-bond geometry to one C(8) atom. In the tenth H site, H(10) is bonded in a single-bond geometry to one C(9) atom. In the eleventh H site, H(11) is bonded in a single-bond geometry to one C(9) atom. In the twelfth H site, H(12) is bonded in a single-bond geometry to one C(9) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Ca(1) and one C(6) atom. In the second O site, O(2) is bonded in a distorted water-like geometry to one Ca(1), one H(1), and one H(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one C(6), one H(1), and one H(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Ca(1) and one C(7) atom. Linkers: 1 [O]C(=O)c1ccc(-c2ccc(C([O])=O)cn2)nc1. Metal clusters: 1 [Ca]. The MOF has largest included sphere 1.54 A, density 1.50 g/cm3, surface area 5181.59 m2/g, accessible volume 0.13 cm3/g