Ca2FeC12H16(N5O)2 crystallizes in the monoclinic C2/c space group. Ca(1) is bonded in a 6-coordinate geometry to one N(1), one N(2), one N(3), one N(4), and two equivalent O(1) atoms. The Ca(1)-N(1) bond length is 2.52 Å. The Ca(1)-N(2) bond length is 2.51 Å. The Ca(1)-N(3) bond length is 2.57 Å. The Ca(1)-N(4) bond length is 2.61 Å. There is one shorter (2.45 Å) and one longer (2.47 Å) Ca(1)-O(1) bond length. Fe(1) is bonded in an octahedral geometry to two equivalent C(1), two equivalent C(2), and two equivalent C(3) atoms. Both Fe(1)-C(1) bond lengths are 1.92 Å. Both Fe(1)-C(2) bond lengths are 1.94 Å. Both Fe(1)-C(3) bond lengths are 1.94 Å. There are seven inequivalent C sites. In the first C site, C(1) is bonded in a linear geometry to one Fe(1) and one N(1) atom. The C(1)-N(1) bond length is 1.17 Å. In the second C site, C(2) is bonded in a linear geometry to one Fe(1) and one N(2) atom. The C(2)-N(2) bond length is 1.16 Å. In the third C site, C(3) is bonded in a linear geometry to one Fe(1) and one N(3) atom. The C(3)-N(3) bond length is 1.17 Å. In the fourth C site, C(4) is bonded to one N(4), one N(5), one H(1), and one H(2) atom to form distorted corner-sharing CH2N2 tetrahedra. The C(4)-N(4) bond length is 1.48 Å. The C(4)-N(5) bond length is 1.48 Å. The C(4)-H(1) bond length is 1.08 Å. The C(4)-H(2) bond length is 1.08 Å. In the fifth C site, C(5) is bonded to one N(4), one N(5), one H(3), and one H(4) atom to form distorted corner-sharing CH2N2 trigonal pyramids. The C(5)-N(4) bond length is 1.48 Å. The C(5)-N(5) bond length is 1.48 Å. The C(5)-H(3) bond length is 1.08 Å. The C(5)-H(4) bond length is 1.08 Å. In the sixth C site, C(6) is bonded to two equivalent N(5) and two equivalent H(5) atoms to form corner-sharing CH2N2 tetrahedra. Both C(6)-N(5) bond lengths are 1.48 Å. Both C(6)-H(5) bond lengths are 1.10 Å. In the seventh C site, C(7) is bonded to two equivalent N(4) and two equivalent H(6) atoms to form corner-sharing CH2N2 tetrahedra. Both C(7)-N(4) bond lengths are 1.49 Å. Both C(7)-H(6) bond lengths are 1.07 Å. There are five inequivalent N sites. In the first N site, N(5) is bonded in a 5-coordinate geometry to one C(4), one C(5), one C(6), one H(2), and one H(8) atom. The N(5)-H(2) bond length is 1.64 Å. The N(5)-H(8) bond length is 1.74 Å. In the second N site, N(1) is bonded in a distorted linear geometry to one Ca(1) and one C(1) atom. In the third N site, N(2) is bonded in a distorted linear geometry to one Ca(1) and one C(2) atom. In the fourth N site, N(3) is bonded in a distorted linear geometry to one Ca(1) and one C(3) atom. In the fifth N site, N(4) is bonded to one Ca(1), one C(4), one C(5), and one C(7) atom to form distorted corner-sharing NCaC3 tetrahedra. There are eight inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(4) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one C(4) and one N(5) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(5) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(5) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(6) 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 O(1) atom. The H(7)-O(1) bond length is 1.01 Å. In the eighth H site, H(8) is bonded in a single-bond geometry to one N(5) and one O(1) atom. The H(8)-O(1) bond length is 0.94 Å. O(1) is bonded in a distorted water-like geometry to two equivalent Ca(1), one H(7), and one H(8) atom. Linkers: 2 C1N2CN3CN1CN(C2)C3. Metal clusters: 4 [Ca] ,2 [Fe]. The MOF has largest included sphere 4.22 A, density 1.49 g/cm3, surface area 3620.45 m2/g, accessible volume 0.20 cm3/g