Synthesis and Structure of Yttrium and Lanthanide Bis(phosphinimino)methanides

Reaction of K{CH(PPh2NSiMe3)2} (1) with anhydrous yttrium or lanthanide trichlorides
leads to [{CH(PPh2NSiMe3)2}LnCl2]2 (Ln = Y (2a), Sm (2b), Er (2c), Dy (2d), Yb (2e), Lu
(2f)). The single-crystal X-ray structures of these complexes show that the methine carbon
is bound to the lanthanide atom. This is supported by DFT calculations, which show a
comparable interaction. Due to the similar ion radii of the lanthanides, the single-crystal
X-ray structures of 2a−f are isostructural. Further reaction of 2 with KNPh2 afforded
[{CH(PPh2NSiMe3)2}Ln(NPh2)2] (Ln = Y (3a), Sm (3b)). These complexes show in comparison
to 2 a similar coordination behavior of the {CH(PPh2NSiMe3)2}- ligand in the solid state
and in solution.