Spectroscopic Investigation of the Gas-Phase Conformations of 15-Crown-5 Ether Complexes with K+

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• 作者：Bruno Martnez-Haya ; Paola Hurtado ; Ana R. Hortal ; Jeffrey D. Steill ; Jos Oomens ; Patrick J. Merkling
• 刊名：Journal of Physical Chemistry A
• 出版年：2009
• 出版时间：July 9, 2009
• 年：2009
• 卷：113
• 期：27
• 页码：7748-7752
• 全文大小：177K
• 年卷期：v.113,no.27(July 9, 2009)
• ISSN：1520-5215

文摘

Infrared multiple photon dissociation action spectra of the binary and ternary gas-phase complexes formed by 15-crown-5 ether with potassium cations (15c5−K⁺ and 15c5−K⁺−15c5) are reported. The spectra span the 800−1500 cm⁻¹ infrared range. Particularly significant differences are found in the position and structure of the CO−stretching band of the two types of complexes. The computational prediction at the DFT−B3LYP/6-31G* level of theory agrees well with the experimental observations, and provides a correlation between the spectral differences and the structural changes associated with the coordination of the ether oxygens with the alkali cation. The 15c5−K⁺ complex adopts a pyramidal structure, with the cation lying above the center of mass of the ether ring at a distance similar to its ionic radius. The ternary 15c5−K⁺−15c5 complex features a less tight coordination of the cation and a relative rotation between the backbones of the two crown ethers, which minimizes the intermolecular repulsions between the oxygens.