Modulating the hydration behaviour of calcium chloride by lactam complexation.

Complexation of calcium chloride with bis(lactam) ligand L1 allows the formation of both an unstable anhydrous complex, an aqua complex {[Ca2(μ-L1)2(H2O)9]Cl4]}n (1) and a related hydrate incorporating additional lattice water of crystallization {[Ca(μ-L1)(H2O)5]Cl2·H2O}n (2). Related mono(lactam) L2 does not form aqua complexes but the anhydrous complex {[CaCl2(μ-L2)2]}n (3), is highly deliquescent. An unusual ethanol solvate is also reported {[CaCl2(L2)(EtOH)]}n (4)