Syntheses and Crystal Structures of Two Metal–Organic Frameworks Formed from Cd2+ Ions Bridged by Long, Flexible 1,7-bis(4-Pyridyl)heptane Ligands with Different Counter-Ions

The ethanol–water layered syntheses and crystal structures of the coordination polymers [Cd(C17H22N2)2(H2O)2]·2(ClO4)·C17H22N2·C2H5OH 2 and [Cd(C17H22N2)2(NO3)2] 3 are reported, where C17H22N2 is a flexible spacer, 1,7-bis(4-pyridyl)heptane. In compound 2, trans-CdO2N4 octahedral nodes are linked by pairs of bridging ligands to result in [001] looped polymeric chains. The chains stack in the [100] direction to form (010) pseudo layers. Sandwiched between them are secondary sheets of free ligands, perchlorate ions and ethanol solvent molecules. Hydrogen bonds between these species help to consolidate the structure. Compound 3 contains trans-CdO2N4 octahedral nodes as parts of regular 44 nets, which propagate in the (103) plane. Three independent nets are interpenetrated.