Behavior of Group 6 Fischer Aminocarbene Complexes in a Supercharged Medium: A Single Electron Transfer−H Atom Transfer Process

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• 作者：Marta L. Lage ; Mara J. Mancheo ; Roberto Martnez-lvarez ; Mar Gmez-Gallego ; Israel Fernndez ; Miguel A. Sierra
• 刊名：Organometallics
• 出版年：2009
• 出版时间：May 11, 2009
• 年：2009
• 卷：28
• 期：9
• 页码：2762-2772
• 全文大小：447K
• 年卷期：v.28,no.9(May 11, 2009)
• ISSN：1520-6041

文摘

The ESI-MS study of the ionization of a series of aryl, alkenyl, and alkynyl (Fischer) aminocarbene complexes is described. The process requires the initial capture of one electron from the ESI source, followed by the transfer of a hydrogen atom to the additive (TTF or Cs₂CO₃). Regardless of their structure, both NH and N,N-disubstituted aminocarbenes can effectively ionize under ESI-MS conditions, as long as they have abstractable H atoms. Overall, the process can be envisaged as a single electron transfer−H atom transfer process. The experimental findings are supported by DFT calculations. The ESI-MS ionization of bis-alkynylaminocarbene complexes follows the same patterns. However, the [M − H]⁻ ions evolve by arylacetylene extrusion together with the usual sequence of CO loss. The process requires the presence of a free NH group and occurs by intramolecular hydrogen transfer from the NH to the metal center. Bis-aminocarbenes having rigid tethers between the nitrogen atoms or lacking free NH groups do not produce this fragmentation.