Pinwheel-shaped heterobimetallic lanthanide alkali metal binaphtholates: Ionic size matters!

Anhydrous alkali metal lanthanide binaphtholates Ms[Ln(binol)(3)] (M = Li, Na; Ln = lanthanide or yttrium; H(2)binol = binaphthol) are prepared by reaction of [Ln{N(SiMe3)(2)}(3)] with 3 equiv of MHbinol. Reaction of [Ln{N(SiMe3)(2)}(3)] (Ln = Y or Yb) with 3 equiv of rac-LiHbinol gives a racemic mixture of RRS- and SSR-Li-3[Ln(binol)(2)](2) as the only product. In contrast, reaction of [Ln{N(SiMe3)(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 S-proton of the unique binol ligand in RRS- and SSR-Li-3[Y(binol)(3)] is shifted upfield by interaction with the pi -system of a neighboring naphthyl ring. Analysis of paramagnetically induced H-1 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(binpl)(3)].THF, 2a; rac-[Na(THF)(2)](3)[Y(binol)(3)], 3; [Li(OEt2)](3-)[Eu(S-binol)(3)] .[Li(OEt2)](3)[Eu(S-binol)(3)(H2O)].2Et(2)O, 4; [Li(THF)(2)](2)[Li(OEt2)][Yb(S-binol)(3)]. THF, 5; [Na(THF)(2)](3)[Yb(S-binol)(3)], 6; [Na(THF)(2)](3)[La(S-binol)(3)(H2O)], 7.