Aggregation and Solvation of Chiral N,P-Amide Ligands in Coordinating Solvents: A Computational and NMR Spectroscopic Study
作者:Petra Rönnholm、Sten O. Nilsson Lill、Jürgen Gräfenstein、Per-Ola Norrby、Mariell Pettersson、Göran Hilmersson
DOI:10.1002/cplu.201200033
日期:2012.9
The lithium amides of a series of chiral N,P ligands were studied in solution. This ligand class had been shown previously to give good selectivities in asymmetric alkylation of benzaldehyde. These lithium amides were found to aggregate into dimers with surprisingly strong coordination of phosphorus to lithium. The equilibrium between dimeric forms was found to depend strongly on non‐bonded interactions
在溶液中研究了一系列手性N,P配体的锂酰胺。先前已证明该配体类别在苯甲醛的不对称烷基化中具有良好的选择性。发现这些酰胺酰胺聚集成二聚体,磷与锂的配位力出乎意料地强。发现二聚体形式之间的平衡在很大程度上取决于溶质内部以及溶质与溶剂之间的非键相互作用。只有将分散度和自由能的贡献比例定为气相值的约20%,才有可能重现实验观察到的聚集偏好。计算了NMR光谱屏蔽物,发现其与实验观察到的位移有很好的相关性。计算得出的Li,P耦合是对Li的敏感度量。P距离。