A series of complexes have been obtained from the crystallisation of M(cdm) (M = Na, K; cdm = carbamoyldicyanomethanide) with crown ethers from aqueous solution. The structures of these complexes display a range of hydrogen-bonding tape and sheet motifs incorporating both coordinated and lattice water molecules. Identical syntheses result in differing degrees of hydration, and consequently different packing, despite only minor changes in the nature of counter-cation. Complexes with 12-crown[4], [Na(12c4)2](cdm)·2H2O 1 and [K(12c4)2](cdm)·H2O 2, both contain metal/crown sandwich complexes between hydrogen-bonded sheets of composition {cdm·xH2O}n (x = 1 or 2, respectively). The incorporation of a slightly larger crown ether in the complex [K(15c5)2](cdm)·H2O 3 incorporates isolated hydrogen-bonded tapes of {cdm·H2O} rather than sheets and has been obtained as two polymorphs. A serendipitous water-free structure, [K(15c5)2](cdm)(cdmH)4, contains a protonated cdm ligand incorporated into 2D sheets with the anionic cdm. The use of 18-crown[6] yields a complex in which the cdm ligand is coordinated to potassium through a nitrile arm, [K(18c6)(cdm)(H2O)] 5. The individual complexes in the structure of 5 join together through a hydrogen-bonded tape that incorporates all available donor and acceptor groups of both the cdm and aqua ligands.