Solution versus solid-state structure of ytterbium heterobimetallic catalysts

被引:64
作者
Di Bari, L
Lelli, M
Pintacuda, G
Pescitelli, G
Marchetti, F
Salvadori, P
机构
[1] Univ Pisa, Dipartimento Chim & Chim Ind, Sez Pisa, ICCOM,CNR, I-56126 Pisa, Italy
[2] Scuola Normale Super Pisa, I-56126 Pisa, Italy
关键词
D O I
10.1021/ja0297640
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The solution structures of the ytterbium heterobimetallic complexes Na-3[Yb((S)-BINOL)(3)] (1), K-3[Yb((S)-BINOL)(3)] (2), and Li-3[Yb((S)-BINOL)(3)] (3), belonging to a family of well-known enantioselective catalysts, are studied by means of NMR and circular dichroism (CD) in the UV and near-IR regions. The experimental NMR paramagnetic shifts were employed to obtain a refined solution structure of 1. NMR analysis demonstrated that 1, 2, and 3 have the same solution geometry but different magnetic susceptibility anisotropy D factors. By comparing XRD and NMR structures of 1, we demonstrate that, upon dissolution, this complex experiences a rearrangement from the crystalline C-3 symmetry into the solution D symmetry. Remarkably, Yb is not bound to water in solution, and Ln-BINOL bonds are labile as demonstrated through EXSY. NIR-CD is confirmed especially sensitive to changes in the ytterbium coordination sphere.
引用
收藏
页码:5549 / 5558
页数:10
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