Li2(Se2O5)(H2O)1.5·CuCl2, a salt-inclusion diselenite structurally based on tetranuclear Li4 complexes†
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 Se2O52− 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.