CaC10N3H4O4 crystallizes in the orthorhombic Cmce space group. Ca(1) is bonded in a 7-coordinate geometry to one N(1), one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms. The Ca(1)-N(1) bond length is 2.54 Å. The Ca(1)-O(2) bond length is 2.46 Å. The Ca(1)-O(3) bond length is 2.42 Å. There is one shorter (2.42 Å) and one longer (2.54 Å) Ca(1)-O(1) bond length. There is one shorter (2.34 Å) and one longer (2.66 Å) Ca(1)-O(4) bond length. There are twelve inequivalent C sites. In the first C site, C(10) is bonded in a trigonal planar geometry to two equivalent C(2) and one N(3) atom. Both C(10)-C(2) bond lengths are 1.38 Å. The C(10)-N(3) bond length is 1.44 Å. In the second C site, C(9) is bonded in a single-bond geometry to two equivalent C(3) and one H(4) atom. Both C(9)-C(3) bond lengths are 1.39 Å. The C(9)-H(4) bond length is 0.93 Å. In the third C site, C(11) is bonded in a distorted single-bond geometry to two equivalent C(6) and one H(5) atom. Both C(11)-C(6) bond lengths are 1.40 Å. The C(11)-H(5) bond length is 0.93 Å. In the fourth C site, C(12) is bonded in a distorted trigonal planar geometry to two equivalent C(7) and one N(4) atom. Both C(12)-C(7) bond lengths are 1.39 Å. The C(12)-N(4) bond length is 1.43 Å. In the fifth C site, C(1) is bonded in a distorted bent 120 degrees geometry to one C(3), one O(3), and one O(4) atom. The C(1)-C(3) bond length is 1.51 Å. The C(1)-O(3) bond length is 1.24 Å. The C(1)-O(4) bond length is 1.26 Å. In the sixth C site, C(2) is bonded in a distorted single-bond geometry to one C(10), one C(3), and one H(1) atom. The C(2)-C(3) bond length is 1.39 Å. The C(2)-H(1) bond length is 0.93 Å. In the seventh C site, C(3) is bonded in a trigonal planar geometry to one C(1), one C(2), and one C(9) atom. In the eighth C site, C(4) is bonded in a bent 120 degrees geometry to one C(6), one O(1), and one O(2) atom. The C(4)-C(6) bond length is 1.50 Å. The C(4)-O(1) bond length is 1.26 Å. The C(4)-O(2) bond length is 1.26 Å. In the ninth C site, C(5) is bonded in a trigonal planar geometry to one N(1), one N(3), and one H(2) atom. The C(5)-N(1) bond length is 1.30 Å. The C(5)-N(3) bond length is 1.35 Å. The C(5)-H(2) bond length is 0.93 Å. In the tenth C site, C(6) is bonded in a trigonal planar geometry to one C(11), one C(4), and one C(7) atom. The C(6)-C(7) bond length is 1.37 Å. In the eleventh C site, C(7) is bonded in a single-bond geometry to one C(12), one C(6), and one H(3) atom. The C(7)-H(3) bond length is 0.93 Å. In the twelfth C site, C(8) is bonded in a water-like geometry to one N(2) and one N(4) atom. The C(8)-N(2) bond length is 1.33 Å. The C(8)-N(4) bond length is 1.31 Å. There are four inequivalent N sites. In the first N site, N(3) is bonded in a trigonal planar geometry to one C(10) and two equivalent C(5) atoms. In the second N site, N(4) is bonded in a trigonal planar geometry to one C(12) and two equivalent C(8) atoms. In the third N site, N(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one C(5), and one N(1) atom. The N(1)-N(1) bond length is 1.38 Å. In the fourth N site, N(2) is bonded in a distorted single-bond geometry to one C(8) atom. There are five inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(2) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(5) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(7) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(9) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(11) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Ca(1) and one C(4) atom. In the second O site, O(2) is bonded in an L-shaped geometry to one Ca(1) and one C(4) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one Ca(1) and one C(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one C(1) atom. Linkers: 4 [O]C(=O)c1cc(C([O])=O)cc(-n2cnnc2)c1 ,4 [O]C(=O)c1cc(C([O])=O)cc(-n2[c]nn[c]2)c1. Metal clusters: 8 [Ca]. The MOF has largest included sphere 7.85 A, density 1.08 g/cm3, surface area 4089.82 m2/g, accessible volume 0.53 cm3/g