Laboratory of Medicinal and Technological Chemistry, University of Brasília (IQ-UnB), Campus Universitário Darcy Ribeiro, CEP 70904970, P.O.Box 4478, Brasília, DF, Brazil.
Institut Parisien de Chimie Moléculaire, UMR 8232, Université Pierre et Marie Curie-Paris6, 4 place Jussieu, 75252, Paris Cedex 05, France.
J Am Soc Mass Spectrom. 2017 Jun;28(6):1021-1029. doi: 10.1007/s13361-017-1637-8. Epub 2017 Apr 7.
Negatively charge-tagged N-heterocyclic carbenes have been formed in solution via deprotonation of imidazolium ions bearing acid side groups and transferred to the gas phase via ESI(-)-MS. The structure of the putative and apparently stable gaseous carbenes formed in such conditions were then probed via reactions with carbon dioxide using a triple quadrupole mass spectrometer particularly optimized for ion/molecule reactions of ESI-generated ions. Complete conversion to imidazolium carboxylates was achieved, which seems to demonstrate the efficiency of the transfer, the gas-phase stability, and the long-lived nature of these unprecedented charge-tagged carbenes and their predominance in the ionic population. Comprehensive studies on the intrinsic reactivity of N-heterocyclic carbenes with silent charge tags are therefore possible. Graphical Abstract ᅟ.
带负电荷的 N-杂环卡宾通过带酸性侧基的咪唑鎓离子的去质子化在溶液中形成，并通过电喷雾（ESI(-)）-MS 转移到气相中。然后，通过使用三重四极杆质谱仪与二氧化碳反应，特别是针对 ESI 产生的离子的离子/分子反应进行优化，探测在这种条件下形成的假定的和显然稳定的气态卡宾的结构。完全转化为咪唑鎓羧酸酯，这似乎证明了转移的效率、气相稳定性以及这些前所未有的带电荷标记的卡宾的长寿命性质及其在离子群体中的优势。因此，可以对具有静音电荷标记的 N-杂环卡宾的固有反应性进行综合研究。
