Metal−Organic Framework H-Bonded Like a Polycatenane:  Coexistence of Acyclic Water Trimer and Nonamer

Pyridine-2,6-dicarboxylic acid and 1,2-di-4-pyridylethylene react hydrothermally with nickel(II) nitrate, forming a metal−organic framework that forms a polycatenane-like structure through H-bonding interactions between water molecules and carboxylate O atoms with void spaces. Discrete acyclic trimeric and nonameric water clusters occupy the voids in the structures. X-ray powder diffraction and X-ray structure analysis have been used to characterize this compound. Crystal data for 1 {(3dpeH₂)[Ni(pdc)₂]₃·15H₂O}:  monoclinic space group P2₁/c, a = 24.730(5) Å, b = 19.895(2) Å, c = 17.257(4) Å, β = 104.832(5)°, V = 8208(4) ų, Z = 4, R1 = 0.0429, wR2 = 0.1072, and S = 1.051.