Synthesis, Crystal Structures, and Ion Pairing of κ$^6N$ Complexes with Rare‐Earth Elements in the Solid State and in Solution

The rare earth element complexes (Ln=Y, La, Sm, Lu, Ce) of several podant κ$^6N$-coordinating ligands have been synthetized and thoroughly characterized. The structural properties of the complexes have been investigated by X-ray diffraction in the solid state and by advanced NMR methods in solution. To estimate the donor capabilities of the presented ligands, an experimental comparison study has been conducted by cyclic voltammetry as well as absorption experiments using the cerium complexes and by analyzing $^{89}$Y NMR chemical shifts of the different yttrium complexes. In order to obtain a complete and detailed picture, all experiments were corroborated by state-of-the-art quantum chemical calculations. Finally, coordination competition studies have been carried out by means of $^1$H and $^{31}$P NMR spectroscopy to investigate the correlation with donor properties and selectivity.