An odd-numbered heptameric water cluster containing a puckered pentamer self-assembled in a Ag(I) polymeric solid

A mixed-ligand Ag(I) coordination polymer {[Ag2(bpe)2(H2O)2](chd)·5H2O}n (1) (bpe = 4,4′-bipyridylethylene, H2chd = 1,4-cyclohexanedicarboxylic acid), has been synthesized and structurally characterized. Complex 1 exhibits a three-dimensional (3-D) supramolecular sandwich architecture that is composed of cationic chains of Ag(I) ions and bpe ligands, alternating with anionic sheets in which uncoordinated chd2 − anions and water molecules form a 2-D hydrogen-bonded network. An odd-numbered (H2O)7 cluster is trapped inside the water-chd aggregation. The discrete water heptamer consists of a puckered pentameric core and two pendent water molecules and structurally shows similarity to the simple hydrocarbon (1,1)-dimethylcyclopentane.