First dipyridylamides of the rare earth elements: New rare earth nitrogen coordinations in [Ln(N(C5H4N)(2))(3)](2), Ln = La, Gd, Yb [German]

摘要

The solvent-free reactions of lanthanum, gadolinium and ytterbium metal with molten 2,2'-Dipyridylamine gave crystalline [Ln(N(C5H4N)(2))(3)](2), Ln = La, Gd, Yb, the crystals being colourless to transparent yellows They are the first examples of dipyridylamides of the rare earth elements. All compounds are homoleptic and exhibit pure nitrogen coordinations of the metal atoms. In addition to end-on chelating dipyridylamide groups further amide ligands are bridging via double chelates using all three nitrogen atoms for coordination. The structures consist of dimers without metal-metal bonds. Because of the large differences in the ionic radii of La-III, Gd-III and Yb-III the coordination spheres differ, arranging the binding modes differently though the stoichiometry is similar. Gd and Yb show a C.N. of eight while La has a C.N. of ten nitrogen atoms. This results in distinctively different crystal structures and IR spectra. [References: 44]