CsKC11H2(NO)4 crystallizes in the triclinic P-1 space group. Cs(1) is bonded in a 8-coordinate geometry to one N(1), two equivalent N(2), two equivalent N(3), one O(4), and two equivalent O(3) atoms. The Cs(1)-N(1) bond length is 3.21 Å. There is one shorter (3.36 Å) and one longer (3.63 Å) Cs(1)-N(2) bond length. There is one shorter (3.21 Å) and one longer (3.52 Å) Cs(1)-N(3) bond length. The Cs(1)-O(4) bond length is 3.16 Å. There is one shorter (3.15 Å) and one longer (3.37 Å) Cs(1)-O(3) bond length. K(1) is bonded in a 7-coordinate geometry to one N(1), one N(2), one N(3), one O(3), one O(4), and two equivalent O(2) atoms. The K(1)-N(1) bond length is 2.86 Å. The K(1)-N(2) bond length is 2.81 Å. The K(1)-N(3) bond length is 2.99 Å. The K(1)-O(3) bond length is 2.89 Å. The K(1)-O(4) bond length is 2.88 Å. There is one shorter (2.72 Å) and one longer (2.80 Å) K(1)-O(2) bond length. There are eleven 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 1.46 Å. The C(1)-C(5) bond length is 1.45 Å. The C(1)-C(6) bond length is 1.40 Å. In the second C site, C(2) is bonded in a distorted single-bond geometry to one C(1), one C(3), and one O(1) atom. The C(2)-C(3) bond length is 1.46 Å. The C(2)-O(1) bond length is 1.25 Å. In the third C site, C(3) is bonded in a trigonal planar geometry to one C(2), one C(4), and one C(9) atom. The C(3)-C(4) bond length is 1.45 Å. The C(3)-C(9) bond length is 1.39 Å. In the fourth C site, C(4) is bonded in a distorted single-bond geometry to one C(3) and one O(2) atom. The C(4)-O(2) bond length is 1.25 Å. In the fifth C site, C(5) is bonded in a distorted single-bond geometry to one C(1) and one O(3) atom. The C(5)-O(3) bond length is 1.25 Å. In the sixth C site, C(6) is bonded in a trigonal planar geometry to one C(1), one C(7), and one C(8) atom. The C(6)-C(7) bond length is 1.41 Å. The C(6)-C(8) bond length is 1.41 Å. In the seventh C site, C(7) is bonded in a distorted linear geometry to one C(6) and one N(1) atom. The C(7)-N(1) bond length is 1.17 Å. In the eighth C site, C(8) is bonded in a distorted single-bond geometry to one C(6) and one N(2) atom. The C(8)-N(2) bond length is 1.17 Å. In the ninth C site, C(9) is bonded in a trigonal planar geometry to one C(10), one C(11), and one C(3) atom. The C(9)-C(10) bond length is 1.42 Å. The C(9)-C(11) bond length is 1.42 Å. In the tenth C site, C(10) is bonded in a distorted linear geometry to one C(9) and one N(3) atom. The C(10)-N(3) bond length is 1.17 Å. In the eleventh C site, C(11) is bonded in a distorted linear geometry to one C(9) and one N(4) atom. The C(11)-N(4) bond length is 1.17 Å. There are four inequivalent N sites. In the first N site, N(1) is bonded in a distorted single-bond geometry to one Cs(1), one K(1), and one C(7) atom. In the second N site, N(2) is bonded in a 1-coordinate geometry to two equivalent Cs(1), one K(1), and one C(8) atom. In the third N site, N(3) is bonded in a distorted single-bond geometry to two equivalent Cs(1), one K(1), and one C(10) atom. In the fourth N site, N(4) is bonded in a single-bond geometry to one C(11) atom. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(4) atom. The H(1)-O(4) bond length is 0.98 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(4) atom. The H(2)-O(4) bond length is 0.98 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one C(2) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(1) and one C(4) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to two equivalent Cs(1), one K(1), and one C(5) atom. In the fourth O site, O(4) is bonded in a water-like geometry to one Cs(1), one K(1), one H(1), and one H(2) atom. Linkers: 2 N#CC(C#N)=c1c(=O)c(=O)c(=C(C#N)C#N)c1=O. Metal clusters: 2 [Cs] ,2 [K]. The MOF has largest included sphere 2.30 A, density 2.08 g/cm3, surface area 2724.59 m2/g, accessible volume 0.10 cm3/g