New crystal structural families of lanthanide chloride – Alcohol/water complexes

The exploration of lanthanide chloride compounds as possible scintillation materials for γ-ray and neutron detection has led to the discovery of several new families of crystal structures with the general formula LnCl3(CH3OH)x(H2O)y. The specific crystal structure depends on the water/methanol content and lanthanide ion. The coordination number of the light (large) lanthanides is the typical value of 8 and reduces to 7 for the heavier (small) lanthanides. The binding energy of water versus alcohol ligands is greater, so that if water is present in the system, it is typically incorporated as a ligand in the crystal. In these crystals, the molecular adducts occur as monomers, dimers, and dichloro-bridged chains. These, in turn, form 3D frameworks through H-bonds to the Cl anions. Other distinct crystal structures are predicted, given the volume changes due to the lanthanide contraction, the water content of the crystal growth solutions, and the specific halide.

The structural hierarchy (monomers, dimers, chains) of lanthanide chloride complexes with water/methanol mixtures depends on the water content and lanthanide contraction.Figure optionsDownload as PowerPoint slideHighlights
► Crystallography of novel lanthanide–halide alcohol solvates.
► Crystal growth from lanthanide chloride alcohol (methanol, ethanol) solutions.
► Molecular adducts as monomers, dimers, and dichloro-bridged chains are observed.