Bis dimethylsilyl amide Complexes

Limited application of the original silylamide route (Sect. 7.1) led to the exploration of the sterically less crowded bis(dimethylsilyl)amide (bdsa) ligand which is also readily available [138]. In contrast to the very similar NiPr2 ligand, the bdsa ligand enables the isolation of pure products via the stoichiometric LnCl3/Li(bdsa) procedure and this favors this system as a synthetic precursor. 

Cl mass spectroscopic studies at temperatures 100°C show the parent molecular ions, but sublimation does not proceed as smoothly as with solvent free Ln(btsa)3. Application of higher temperatures (ca. 150 °C) results in the release of THF followed by the detection of dinuclear species in the mass spectra. The THF ligands in Y(bdsa)3(THF)2 could be replaced by stronger donor molecules as the carbene ligand l,4-dimethylimidazol-2-ylidene [140]. The bdsa ligand is rather flexible in these exchange reactions to afford both mono, Y(bdsaXL), and bis (carbene) adducts Y(bdsa)(L2), respectively. 

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