PUB - Publikationen an der Universität Bielefeld

Tris(tetramethylaluminate)s of the lanthanoids cerium (1), holmium (2), and erbium (3) were synthesized by treating lanthanoid amide complexes of the type [Ln(NMe2)(3)(LiCl)(3)] with an excess amount of AlMe3. These compounds were characterized by single-crystal X-ray diffraction, elemental analysis, and NMR spectroscopy. Paramagnetic NMR spectroscopic studies were undertaken to investigate the influence of the compounds on the solvent chemical shifts. NMR parameters for the H-1, C-13, and Al-27 nuclei of all the reported lanthanoid tris(tetramethylaluminate)s were measured. The reactions of tris(tetramethylaluminate)s of samarium and holmium with an excess amount of tetrahydrofuran led to [LnMe(2)(thf)(5)][AlMe4] {Ln = Ho (4), Sm (5)}. NMR spectroscopic investigations of the paramagnetic holmium and samarium methyl compounds (i.e., 4, 5) as well as the known diamagnetic analogue [YMe2(thf)(5)][AlMe4] revealed methyl group exchange processes in solution.