Frański R. Gas-phase stability of sandwich complexes of crown ethers with metal cations - as studied by collision induced dissociation tandem mass spectrometry.
RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018;
32:1651-1657. [PMID:
29943475 DOI:
10.1002/rcm.8215]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 05/13/2018] [Accepted: 06/14/2018] [Indexed: 06/08/2023]
Abstract
RATIONALE
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+ , Ca2+ , Sr2+ , Ba2+ , Pb2+ , Hg2+ , Cd2+ ) 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.
METHODS
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.
RESULTS
The gas-phase stabilities of [(B12C4)2 +Tl]+ , [(B15C5)2 +SrNO3 ]+ , [(B15C5)2 +PbNO3 ]+ and [(B15C5)2 +SrCl]+ were higher than those of [(12C4)2 +Tl]+ , [(15C5)2 +SrNO3 ]+ , [(15C5)2 +PbNO3 ]+ and [(15C5)2 +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.
CONCLUSIONS
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 Sr2+ and Pb2+ .
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