EuC6N2H2O5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 8-coordinate geometry to one N(1), one O(1), one O(4), one O(5), one O(8), one O(9), and two equivalent O(10) atoms. The Eu(1)-N(1) bond length is 2.58 Å. The Eu(1)-O(1) bond length is 2.46 Å. The Eu(1)-O(4) bond length is 2.34 Å. The Eu(1)-O(5) bond length is 2.53 Å. The Eu(1)-O(8) bond length is 2.36 Å. The Eu(1)-O(9) bond length is 2.41 Å. There is one shorter (2.39 Å) and one longer (2.43 Å) Eu(1)-O(10) bond length. In the second Eu site, Eu(2) is bonded in a 8-coordinate geometry to one N(3), one O(1), one O(10), one O(3), one O(5), one O(7), and two equivalent O(9) atoms. The Eu(2)-N(3) bond length is 2.59 Å. The Eu(2)-O(1) bond length is 2.51 Å. The Eu(2)-O(10) bond length is 2.41 Å. The Eu(2)-O(3) bond length is 2.39 Å. The Eu(2)-O(5) bond length is 2.45 Å. The Eu(2)-O(7) bond length is 2.38 Å. There is one shorter (2.41 Å) and one longer (2.42 Å) Eu(2)-O(9) bond length. There are twelve inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one O(1) and one O(2) atom. The C(1)-O(1) bond length is 1.29 Å. The C(1)-O(2) bond length is 1.23 Å. In the second C site, C(2) is bonded in a distorted single-bond geometry to one N(1) atom. The C(2)-N(1) bond length is 1.34 Å. In the third C site, C(3) is bonded in a distorted single-bond geometry to one C(4) and one H(1) atom. The C(3)-C(4) bond length is 1.37 Å. The C(3)-H(1) bond length is 0.93 Å. In the fourth C site, C(4) is bonded in a distorted trigonal planar geometry to one C(3), one C(5), and one N(2) atom. The C(4)-C(5) bond length is 1.51 Å. The C(4)-N(2) bond length is 1.34 Å. In the fifth C site, C(5) is bonded in a distorted bent 120 degrees geometry to one C(4), one O(3), and one O(4) atom. The C(5)-O(3) bond length is 1.25 Å. The C(5)-O(4) bond length is 1.24 Å. In the sixth C site, C(6) is bonded in a trigonal planar geometry to one N(1), one N(2), and one H(2) atom. The C(6)-N(1) bond length is 1.34 Å. The C(6)-N(2) bond length is 1.33 Å. The C(6)-H(2) bond length is 0.93 Å. In the seventh C site, C(7) is bonded in a distorted bent 120 degrees geometry to one C(8), one O(5), and one O(6) atom. The C(7)-C(8) bond length is 1.50 Å. The C(7)-O(5) bond length is 1.29 Å. The C(7)-O(6) bond length is 1.23 Å. In the eighth C site, C(8) is bonded in a distorted single-bond geometry to one C(7), one C(9), and one N(3) atom. The C(8)-C(9) bond length is 1.38 Å. The C(8)-N(3) bond length is 1.33 Å. In the ninth C site, C(9) is bonded in a distorted single-bond geometry to one C(10), one C(8), and one H(3) atom. The C(9)-C(10) bond length is 1.38 Å. The C(9)-H(3) bond length is 0.93 Å. In the tenth C site, C(10) is bonded in a distorted trigonal planar geometry to one C(11), one C(9), and one N(4) atom. The C(10)-C(11) bond length is 1.52 Å. The C(10)-N(4) bond length is 1.35 Å. In the eleventh C site, C(11) is bonded in a distorted bent 120 degrees geometry to one C(10), one O(7), and one O(8) atom. The C(11)-O(7) bond length is 1.24 Å. The C(11)-O(8) bond length is 1.25 Å. In the twelfth C site, C(12) is bonded in a trigonal planar geometry to one N(3), one N(4), and one H(4) atom. The C(12)-N(3) bond length is 1.34 Å. The C(12)-N(4) bond length is 1.34 Å. The C(12)-H(4) bond length is 0.93 Å. There are four inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal planar geometry to one Eu(1), one C(2), and one C(6) atom. In the second N site, N(2) is bonded in a bent 120 degrees geometry to one C(4) and one C(6) atom. In the third N site, N(3) is bonded in a distorted trigonal planar geometry to one Eu(2), one C(12), and one C(8) atom. In the fourth N site, N(4) is bonded in a bent 120 degrees geometry to one C(10) and one C(12) atom. There are four inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one C(3) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(6) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(9) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(12) atom. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Eu(1), one Eu(2), and one C(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one C(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Eu(2) and one C(5) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Eu(1) and one C(5) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Eu(1), one Eu(2), and one C(7) atom. In the sixth O site, O(6) is bonded in a single-bond geometry to one C(7) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Eu(2) and one C(11) atom. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Eu(1) and one C(11) atom. In the ninth O site, O(9) is bonded in a trigonal non-coplanar geometry to one Eu(1) and two equivalent Eu(2) atoms. In the tenth O site, O(10) is bonded in a trigonal non-coplanar geometry to one Eu(2) and two equivalent Eu(1) atoms. Linkers: 8 [O]C(=O)c1cc(C([O])=O)ncn1. Metal clusters: 8 [Eu]. The MOF has largest included sphere 5.40 A, density 2.25 g/cm3, surface area 2194.32 m2/g, accessible volume 0.15 cm3/g