Frański Rafał
Rapid Commun Mass Spectrom. 2018 Jun 25. doi: 10.1002/rcm.8215.
The gas-phase stabilities of the sandwich complexes formed by 12-crown-4 or 15-crown-5 with metal cations (Na , K , Rb , Tl , Ag , Ca , Sr , Ba , Pb , Hg , Cd ) are compared with the stability of the sandwich complex formed by benzo-12-crown-4 or benzo-15-crown-5 with the cations. It is interesting to check if the possible cation-π interactions increase the gas-phase stabilities of the sandwich complexes of benzo-crown ethers with metal cations.
The sandwich complexes were generated in the gas phase by electrospray ionization (ESI) and then they were subjected to the collision induced dissociation tandem mass spectrometry experiments (CID-MS/MS). On the basis of the obtained product ion spectra, the respective breakdown plots of the ion abundances ratios against collision energy expressed in the terms of center-of-mass were made.
The gas-phase stabilities of [(B12C4) +Tl] , [(B15C5) +SrNO ] , [(B15C5) +PbNO ] and [(B15C5) +SrCl] were higher than those of [(12C4) +Tl] , [(15C5) +SrNO ] , [(15C5) +PbNO ] and [(15C5) +SrCl] , respectively. For the other sandwich complexes the stabilities of the complexes with benzo-crown ethers were not higher than those of the complexes of simple crown ethers.
It is reasonable to assume that the cation-π interaction increases the stability of the sandwich complex of B12C4 with Tl and the stabilities of sandwich complexes of B15C5 with Sr and Pb .
比较了12-冠-4或15-冠-5与金属阳离子（Na⁺、K⁺、Rb⁺、Tl⁺、Ag⁺、Ca²⁺、Sr²⁺、Ba²⁺、Pb²⁺、Hg²⁺、Cd²⁺）形成的夹心配合物的气相稳定性，以及苯并-12-冠-4或苯并-15-冠-5与这些阳离子形成的夹心配合物的稳定性。检验可能的阳离子-π相互作用是否会增加苯并冠醚与金属阳离子形成的夹心配合物的气相稳定性是很有意思的。
通过电喷雾电离（ESI）在气相中生成夹心配合物，然后对其进行碰撞诱导解离串联质谱实验（CID-MS/MS）。根据获得的产物离子光谱，绘制了以质心表示的离子丰度比相对于碰撞能量的各自的分解图。
[(B12C4)⁺Tl]、[(B15C5)⁺SrNO]、[(B15C5)⁺PbNO]和[(B15C5)⁺SrCl]的气相稳定性分别高于[(12C4)⁺Tl]、[(15C5)⁺SrNO]、[(15C5)⁺PbNO]和[(15C5)⁺SrCl]。对于其他夹心配合物，含苯并冠醚的配合物的稳定性不高于简单冠醚配合物的稳定性。
合理推测阳离子-π相互作用增加了B12C4与Tl形成的夹心配合物的稳定性以及B15C5与Sr和Pb形成的夹心配合物的稳定性。
