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

Abstract

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.

Nonlinear Effects in Asymmetric Catalysis

“…Shibasaki and co-workers [58b] Racemic binol resulted in the exclusive formation of heterochiral complexes, in agreement with earlier observations by Aspinall et al [59] (40) and Shibasaki and co-workers (39 a).…”

Evidence for Substrate Binding by the Lanthanide Centers in [Li3(thf)n(binolate)3Ln]: Solution and Solid‐State Characterization of Seven‐ and Eight‐Coordinate [Li3(sol)n(binolate)3Ln(S)m] Adducts

“…[20,21] The characterization of eight-coordinate [Li 3 (py) 5 A C H T U N G T R E N N U N G (binolate) 3 La(py) 2 ] lends support to this proposal for larger lanthanides and indicates that the lanthanide centers can expand their coordination number beyond seven, the proposed maximum for this important class of compounds. [22] Experimental Section 8: Complex 2 (30 mg) was added to a vial and dissolved in pyridine (1.0 mL).…”

“…[5] To probe the binding of softer ligands to the lanthanide center, we crystallized [Li 3 (py) 5 A C H T U N G T R E N N U N G (binolate) 3 La(py) 2 ] (8) (py = pyridine) by diffusion of pentane into a solution of 2 in pyridine at room temperature. An ORTEP diagram of 8 is shown in Figure 3.…”

“…and [M 3 A C H T U N G T R E N N U N G (thf) n -A C H T U N G T R E N N U N G (binolate) 3 LnA C H T U N G T R E N N U N G (OH 2 )] [1,5,7,8] complexes have been characterized crystallographically. [9] The lanthanide centers in these structures are either six-coordinate (Figure 1) or sevencoordinate when bound to a water molecule.…”

Crystal structure of chiral binaphthol lanthanide complexes and their catalysis in asymmetric transfer hydrogenation of acetophenone

“…Ingress of sufficient atmospheric moisture into the Schlenk tube to form this mixture was expected to be a slow process, which also occurred in a previous report. 6 Nevertheless, an attempt to synthesize mono-or di-R-Binaphthoxy bromide lanthanide complexes, with regard to the mono-R-Binaphthoxide diiodo lanthanide complexes, was not successful starting with either LnBr 3 or LnCl 3 . Both Ln-Cl and Ln-Br bonds were cleaved during the reactions.…”