Energy-resolved collision-induced dissociation cross sections of 2:1 bis-oxazoline copper complexes. Nonbonded interactions and nonlinear effects.
Energy-resolved collision-induced dissociation cross sections of 2:1 bis-oxazoline copper complexes. Nonbonded interactions and nonlinear effects.
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2:1 双恶唑啉铜配合物的能量分辨碰撞诱导解离截面。
DOI：
10.1021/ja065390p
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发表时间：
2007
影响因子：
15
通讯作者：
Peter Chen
中科院分区：
文献类型：
--
作者：
Eva Zocher;R. Dietiker;Peter Chen
通过拟合能量分辨碰撞诱导解离截面，确定了双恶唑啉配体与Cu(I)气相2:1配合物的绝对配体结合能。选择这些配合物是因为它们存在于不对称催化中，其非线性效应现象可以用同手性和杂手性配合物的稳定性差异来解释。伪对映体配体的使用，使质谱测量可以采用。测量发现，异丙基取代基与苯基取代基在空间上相似，但电子上不同，导致了异手性配合物与杂手性配合物的不同稳定性顺序，从而导致了异丙基取代配体配合物在不对称催化中的非线性效应的预测。稳定性顺序差异的起源是在配体上苯基之间的非共价相互作用中发现的，这是DFT计算难以描述的。
Absolute ligand binding energies are determined for the 2:1 complexes of bis-oxazoline ligands and Cu(I) in the gas phase by the fitting of energy-resolved collision-induced dissociation cross sections. The complexes were chosen for their occurrence in asymmetric catalysis for which the phenomenon of nonlinear effects is explained by differences in stability for homochiral and heterochiral complexes. Pseudo-enantiomeric ligands are used so that mass spectrometric measurements can be employed. The measurements find that the sterically similar, but electronically different, isopropyl versus phenyl substituents lead to a different stability ordering of the homo- versus heterochiral complexes, which then leads to the prediction of nonlinear effects in asymmetric catalysis by the complexes with isopropyl-substituted ligands. The origin of the difference in stability order is found in noncovalent interactions between the phenyl groups on the ligands, which are poorly described by DFT calculations.