Novel series of ribbon structures in dialkylammonium chlorocadmates obtained by dimensional reduction of the hexagonal CdCl2 lattice

Small dialkylammonium cations (DMA(+) = dimethylammonium, DEA(+) = diethylammonium, and DPA(+) = dipropylammonium) were used as molecular scissors to obtain ribbon structures based on edge-sharing octahedra derived from the parent hexagonal CdCl2 lattice. Retro-crystal engineering concepts were used to analyze and interpret the observed structures. The chloride salts all contain coordinated solvent molecules that stabilize the ribbon structures through O-H center dot center dot center dot Cl hydrogen bonds. The simplest of these, the alpha and beta polymorphs of [DEA][Cd2Cl5(H2O)], are made up of double chains of edge-shared octahedra with stoichiometry [Cd2Cl5(H2O)(-)](infinity). The more complex ribbon structures found in [DMA][Cd2Cl5(H2O)]-H2O, [DPA](2)[Cd5Cl12(H2O)(2)]center dot H2O, and [DPA](2)[Cd3Cl8(CH3OH)]center dot H2O are made up of [Cd4Cl10(H2O)(2)(2-)](infinity), [Cd5Cl12(H2O)(2)(2-)](infinity), and [Cd6Cl16(CH3OH)(2)(2-)](infinity) moieties, each with its own distinctive packing characteristics. A wide selection of hydrogen bonding plays a crucial role in the three-dimensional stability of this unique family of structures.