A new lithium copper diselenite chloride hydrate, Li2Se2O5(H2O)1.5·CuCl2, was prepared from aqueous
solution. Its unique 2D structure can be interpreted as Li2Se2O5(H2O)1.5 layers with CuCl2 hosts embedded
in the interlayer space, and be considered halfway between the salt-inclusion and host–guest structures.
The CuO2Cl4 octahedra form chains similar to those in CuCl2·2H2O, yet water molecules are coordinated
exclusively to Li+ while Se2O5
2− and Cl− bridge Li+ and Cu2+. The complexity of the structure is likely
responsible for both very long pre-crystallization time and non-existence of the corresponding bromide
analogue. Despite the relatively long Cu⋯Cu separations, the compound exhibits weak ferromagnetic
interactions along the chains of CuO2Cl4 octahedra.