Chiral Lanthanide Complexes: Coordination Chemistry and Applications

Aspinall, Helen C.

doi:10.1021/cr010288q

Cited by 543 publications

(208 citation statements)

References 267 publications

(424 reference statements)

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“…When comparing M 3 (THF) 6 (BINOLate) 3 Ln structures, we found three interdependent factors to be important. The first and most informative aspect of these structures is the presence of Na-C cation-π interactions.…”

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confidence: 93%

“…In contrast to 7-and 8-coordinate Li 3 (THF) 4 (BINOLate) 3 Ln•THF (Ln=Eu, La) and Li 3 (py) 5 (BINOLate) 3 La•py 2 , 8 Na 3 (THF) 6 (BINOLate) 3 Ln are only 6-coordinate.…”

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confidence: 98%

“…Why does M 3 (THF) n (BINOLate) 3 Ln readily bind substrates when M = Li but not when M = Na or K? Structural studies herein indicate Na-and K-C cation-π interactions and alkali metal radius may be more important than even lanthanide radius.…”

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confidence: 99%

“…To probe the influence of Li vs. Na on substrate binding at the lanthanide, Na 3 (THF) 6 (BINOLate) 3 La ( Figure 3) and isostructural Na 3 (THF) 6 (BINOLate) 3 Eu ( Figure S1) were crystallographically characterized. In contrast to 7-and 8-coordinate Li 3 (THF) 4 (BINOLate) 3 Ln•THF (Ln=Eu, La) and Li 3 (py) 5 (BINOLate) 3 La•py 2 , 8 Na 3 (THF) 6 (BINOLate) 3 Ln are only 6-coordinate.…”

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confidence: 99%

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Impact of Na− and K−C π-Interactions on the Structure and Binding of M₃(sol)_n(BINOLate)₃Ln Catalysts

2007

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Shibasaki's heterobimetallic complexes M 3 (THF) n (BINOLate) 3 Ln [M = Li, Na, K, Ln = lanthanide (III)] are among the most successful asymmetric Lewis acid catalysts. Why does M 3 (THF) n (BINOLate) 3 Ln readily bind substrates when M = Li but not when M = Na or K? Structural studies herein indicate Na-and K-C cation-π interactions and alkali metal radius may be more important than even lanthanide radius. Also reported is a novel polymeric [K 3 (THF) 2 (BINOLate) 3 Yb] n structure that provides the first evidence of interactions between M 3 (THF) n (BINOLate) 3 Ln complexes.Shibasaki's M 3 (THF) n (BINOLate) 3 Ln complexes (Figure 1) are among the most effective asymmetric Lewis acid catalysts known, exhibiting high enantioselectivities over a broad range of reactions. 1-3 Understanding how these heterobimetallic catalysts work, however, has proven challenging. 4-9 In particular, seemingly subtle alterations in the catalyst composition result in dramatic changes in selectivity. For example, in the nitro aldol reaction with M 3 (THF) n (BINOLate) 3 Ln, 94% ee was obtained when M = Li and 2% ee when M = Na. In contrast, the asymmetric Michael reaction gave 92% ee when M = Na and 29% ee for M = Li. 10 The first step in unraveling the factors that are responsible for these striking differences is understanding the impact of the alkali metal on substrate binding to the lanthanide centers.Reported herein are solution and solid state studies of M 3 (sol) n (BINOLate) 3 Ln complexes that illuminate dramatic differences in Ln binding ability when M = Li vs. Na and K. Also disclosed is an unprecedented helical polymer, [K 3 We recently demonstrated that DMF reversibly binds to paramagnetic lanthanides in Li 3 (THF) n (BINOLate) 3 Ln (Ln = Eu, Pr), exhibiting > 2 ppm lanthanide induced shift (LIS) in the formyl C-H resonance in the 1 H NMR spectrum. 8 Salvadori, on the other hand, reported 7 that Na 3 (THF) 6 (BINOLate) 3 Yb does not bind water in solution or the solid state, which was attributed to the small ionic radius of Yb (La = 1.17, Eu = 1.09, Yb = 1.01). This dichotomy prompted us to examine binding of the lithium analog, Li 3 (THF) n (BINOLate) 3 Yb, with DMF. In the presence of Li 3 (THF) n (BINOLate) 3 Yb, the formyl C-H shifted over 4 ppm, consistent with binding to Yb. Furthermore, crystallization of Li 3 (THF) n (BINOLate) 3 Yb from pyridine yielded 7-coordinate Li 3 (py) 5 (BINOLate) 3 Yb•py, the ORTEP of which is shown in Figure 2. We next examined binding of DMF to Na 3 (THF) 6 (BINOLate) 3 Ln [Ln = Yb, Eu] 11-13 and K 3 (THF) 6 (BINOLate) 3 Yb 14,7 under the same conditions. Surprisingly, no LISs (>0.1 ppm) were observed, indicating that binding to the lanthanide in the Na and K analogs is much less favorable than in the Li series.

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confidence: 93%

“…In contrast to 7-and 8-coordinate Li 3 (THF) 4 (BINOLate) 3 Ln•THF (Ln=Eu, La) and Li 3 (py) 5 (BINOLate) 3 La•py 2 , 8 Na 3 (THF) 6 (BINOLate) 3 Ln are only 6-coordinate.…”

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confidence: 98%

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confidence: 99%

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confidence: 99%

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Impact of Na− and K−C π-Interactions on the Structure and Binding of M₃(sol)_n(BINOLate)₃Ln Catalysts

2007

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“…3 An alternative approach, the use of chiral donor molecules, generally results only in poorly conductive materials. 4 In stark contrast to optically pure chiral cations, [5][6][7][8][9][10][11] only a few families of optically pure complex anions are known. This…”

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confidence: 99%

TTF salts of optically pure cobalt pyridine amidates; detection of soluble assemblies with stoichiometry corresponding to the solid state

et al. 2011

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Tris[1,1,1-trimethyl-N-(trimethylsilyl)silanaminato]-yttrium

Matsunaga

2008

Encyclopedia of Reagents for Organic Synthesis

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Chiral Lanthanide Complexes: Coordination Chemistry and Applications

Cited by 543 publications

References 267 publications

Impact of Na− and K−C π-Interactions on the Structure and Binding of M₃(sol)_n(BINOLate)₃Ln Catalysts

Impact of Na− and K−C π-Interactions on the Structure and Binding of M₃(sol)_n(BINOLate)₃Ln Catalysts

TTF salts of optically pure cobalt pyridine amidates; detection of soluble assemblies with stoichiometry corresponding to the solid state

Tris[1,1,1-trimethyl-N-(trimethylsilyl)silanaminato]-yttrium

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Chiral Lanthanide Complexes: Coordination Chemistry and Applications

Cited by 543 publications

References 267 publications

Impact of Na− and K−C π-Interactions on the Structure and Binding of M3(sol)n(BINOLate)3Ln Catalysts

Impact of Na− and K−C π-Interactions on the Structure and Binding of M3(sol)n(BINOLate)3Ln Catalysts

TTF salts of optically pure cobalt pyridine amidates; detection of soluble assemblies with stoichiometry corresponding to the solid state

Tris[1,1,1-trimethyl-N-(trimethylsilyl)silanaminato]-yttrium

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Impact of Na− and K−C π-Interactions on the Structure and Binding of M₃(sol)_n(BINOLate)₃Ln Catalysts

Impact of Na− and K−C π-Interactions on the Structure and Binding of M₃(sol)_n(BINOLate)₃Ln Catalysts