对与[14N,15N]-N,N,N',N'-四甲基乙二胺络合的[6Li]-烯丙基锂化合物的结构和重组动力学的核磁共振研究：反转和配体锂交换

NMR studies of structure and reorganization dynamics of an [6Li]-allylic lithium compound complexed to [14N,15N]-N,N,N',N'-tetramethylethylenediamine: inversion and ligand lithium exchange.

作者信息

Fraenkel Gideon, Liu Hua

机构信息

Department of Chemistry, Ohio State University, Columbus, Ohio 43210 USA.

出版信息

J Am Chem Soc. 2004 Apr 28;126(16):5202-6. doi: 10.1021/ja030285q.

DOI:10.1021/ja030285q

PMID:15099103

Abstract

Proton, 13C, 6Li, and 15N NMR line-shape studies of exo,exo-1-trimethylsilyl-3-(dimethylethylsilyl)allyllithium-6Li complexed to [14N,15N]-N,N,N',N'-tetramethylethylenediamine (TMEDA) 2 as a function of temperature and of added diamine reveal the dynamics of three fast equilibrium reorganization processes. These are (with DeltaH values in kilocalories per mole and DeltaS values in entropic units): mutual exchange of lithium between two 2 molecules (6.3, -21), exchange of TMEDA between its free and complexed states (5.0 and -22), and first-order transfer of complexed ligand between the allyl faces (7.0 and -20). Intermediates that are dimeric in TMEDA are proposed for the first two of these reorganization processes.

摘要

对与[14N,15N]-N,N,N',N'-四甲基乙二胺（TMEDA）2络合的外向，外向-1-三甲基甲硅烷基-3-（二甲基乙基甲硅烷基）烯丙基锂-6Li配合物进行质子、13C、6Li和15N核磁共振线形研究，研究其作为温度和添加二胺的函数，揭示了三个快速平衡重组过程的动力学。这些过程是（以千卡每摩尔为单位的ΔH值和以熵单位为单位的ΔS值）：锂在两个2分子之间的相互交换（6.3，-21），TMEDA在其游离态和络合态之间的交换（5.0和-22），以及络合配体在烯丙基面之间的一级转移（7.0和-20）。对于这些重组过程中的前两个过程，提出了在TMEDA中为二聚体的中间体。