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Type: Artigo de periódico
Title: N-heterocyclic carbenes with negative-charge tags: direct sampling from ionic liquid solutions
Author: Lalli, PM
Rodrigues, TS
Arouca, AM
Eberlin, MN
Neto, BAD
Abstract: Herein we report on the sampling and characterization via electrospray ionization (tandem) mass spectrometry of free, long-lived N-heterocyclic carbenes (NHC) bearing negative-charge tags. To facilitate electrospray 'ion fishing' via electrostatic ejection directly to the gas phase, negative-charge tagged NHC were formed in imidazolium-based ionic liquid solutions via double deprotonation of imidazolium cations bearing acid side groups, viz. CH2CO2H or (CH2)(3)SO3H. Via ESI-MS/MS experiments, the gaseous N-heterocyclic carbenes were found to display structurally diagnostic dissociations and bimolecular reactions. In perfect parallel to solution chemistry, the gaseous negative-charge tagged NHC were found to react promptly with CO2 by carboxylation to form negative-charge tagged imidazolium carboxylates. Neutral carbenes were inaccessible for mass spectrometry, but the charge tag strategy opens many new possibilities to explore the intrinsic chemistry of these key but elusive species.
Country: Inglaterra
Editor: Royal Soc Chemistry
Citation: Rsc Advances. Royal Soc Chemistry, v. 2, n. 8, n. 3201, n. 3203, 2012.
Rights: aberto
Identifier DOI: 10.1039/c2ra01360f
Date Issue: 2012
Appears in Collections:Unicamp - Artigos e Outros Documentos

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