Pinwheel-Shaped Heterobimetallic Lanthanide Alkali Metal Binaphtholates: Ionic Size Matters!

Anhydrous alkali metal lanthanide binaphtholates M 3 [Ln(binol) 3 ] (M = Li, Na; Ln = lanthanide or yttrium; H 2 binol = binaphthol) are prepared by reaction of [Ln{N(SiMe 3 ) 2 } 3 ] with 3 equiv of MHbinol. Reaction of [Ln{N(SiMe 3 ) 2 } 3 ] (Ln = Y or Yb) with 3 equiv of rac -LiHbinol gives a racemic mixture of RRS - and SSR -Li 3 [Ln(binol) 3 ] 2 as the only product. In contrast, reaction of [Ln{N(SiMe 3 ) 2 } 3 ] with 3 equiv of rac -NaHbinol gives a racemic mixture of RRR - and SSS -Na 3 [Ln(binol) 3 ] when Ln = Y. When Ln = Yb, a 3:1 mixture of RRR-/SSS- and RRS-/SSR- Na 3 [Ln(binol) 3 ] is formed. Complexes have been characterized in solution by NMR spectroscopy. The 3-proton of the unique binol ligand in RRS - and SSR -Li 3 [Y(binol) 3 ] is shifted upfield by interaction with the π-system of a neighboring naphthyl ring. Analysis of paramagnetically induced 1 H NMR shifts of Yb complexes shows them to be entirely dipolar in origin. X-ray crystal structures have been determined for the following compounds: rac -[Li(THF) 2 ] 3 [Y(binol) 3 ]·THF, 2a; rac -[Na(THF) 2 ] 3 [Y(binol) 3 ], 3; [Li(OEt 2 )] 3 [Eu( S -binol) 3 ]·[Li(OEt 2 )] 3 [Eu( S -binol) 3 (H 2 O)]·2Et 2 O, 4; [Li(THF) 2 ] 2 [Li(OEt 2 )][Yb( S -binol) 3 ]·THF, 5; [Na(THF) 2 ] 3 [Yb( S -binol) 3 ], 6; [Na(THF) 2 ] 3 [La( S -binol) 3 (H 2 O)], 7 .