Frameworks by Solvent-Free Synthesis of Rare Earth Chlorides with Molten 1,3-Benzodinitrile and Tailoring of the Particle Size: ∞3[LnCl3{1,3-C6H4(CN)2}], Ln = Y, Dy, Ho, Er, Yb

The solvent-free melt reactions of anhydrous rare earth trichlorides with molten 1,3-benzodinitrile [1,3-C6H4(CN)(2), C8H4N2] result in isophthalonitrile frameworks of the rare earth elements. The particle size of the products can be varied from the millimeter to the nanometer scale (down to 50-400 nm) depending on the synthesis conditions. Thus, these network structures are among the very few coordination polymers that can be synthesized as nanoparticles. A constitution of 1:1 concerning LnCl(3)/1,3-C6H4(CN)(2) is found for Y (1), Dy (2), Ho (3), Er (4), and Yb (5) in isotypic (3)(infinity)[LnCl(3){1,3-C6H4(CN)(2)}]. The ligand 1,3-C6H4(CN)(2) functions both as chemical scissors and replaces chloride linkages by degrading the rare earth chloride structures, and subsequently forms new 3D-framework structures. They consist of strands of chlorido-coordinated lanthanide atoms, which are linked in two dimensions by 1,3-C6H4(CN)(2) molecules. Compounds 1-5 were obtained as single crystals from the melt reaction, and their crystal structures were determined by single-crystal X-ray analysis. They can also be obtained as nanocrystalline materials from a ball mill treatment, identified by electron microscopy (REM) and EDX analysis.