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Gas‐phase stability of sandwich complexes of crown ethers with metal cations – as studied by collision‐induced dissociation tandem mass spectrometry
Author(s) -
Frański Rafał
Publication year - 2018
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.8215
Subject(s) - chemistry , dissociation (chemistry) , electrospray ionization , metal , collision induced dissociation , mass spectrometry , mass spectrum , ion , 15 crown 5 , analytical chemistry (journal) , tandem mass spectrometry , gas phase , inorganic chemistry , crown ether , organic chemistry , chromatography
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 + , Ca 2+ , Sr 2+ , Ba 2+ , Pb 2+ , Hg 2+ , Cd 2+ ) are compared with the stability of the sandwich complexes 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 collision‐induced dissociation tandem mass spectrometry (CID‐MS/MS) experiments. 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 + SrNO 3 ] + , [( B15C5 ) 2 + PbNO 3 ] + and [( B15C5 ) 2 + SrCl] + were higher than those of [( 12C4 ) 2 + Tl] + , [( 15C5 ) 2 + SrNO 3 ] + , [( 15C5 ) 2 + PbNO 3 ] + 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 with 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 Sr 2+ and Pb 2+ .