Helium-Plasma-Ionization Mass Spectrometry of Metallocenes and Their Derivatives
Julius Pavlov1, Zhaoyu Zheng1, David Douce2
1Center for Mass Spectrometry, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States.
Journal of the American Society for Mass Spectrometry
|January 4, 2021
Summary
Helium-plasma ionization (HePI) efficiently ionizes ferrocene and nickelocene, enabling manipulation of protonation and fragmentation. Hydrogen-deuterium exchange reactions are also readily performed in the ion source.
Area of Science:
- Analytical Chemistry
- Mass Spectrometry
- Organometallic Chemistry
Background:
- Ferrocene and nickelocene are organometallic compounds with unique electronic properties.
- Ionization techniques are crucial for the analysis of such compounds.
- Helium-plasma ionization (HePI) offers a novel approach for gas-phase ion generation.
Purpose of the Study:
- To investigate the ionization behavior of ferrocene and nickelocene using a helium-plasma ionization (HePI) source.
- To explore the potential for manipulating ion populations and performing gas-phase reactions within the ion source.
- To characterize fragmentation pathways and study protonation mechanisms in metallocenes.
Main Methods:
- Direct exposure of ferrocene and nickelocene to the ionizing plasma of a helium-plasma ionization (HePI) source.
- Analysis of mass spectra under ambient positive-ion-generating conditions.
- In-source collision-induced dissociation (CID) and hydrogen-deuterium exchange (HDX) reactions using a modified heating gas.
Main Results:
- Facile ionization of ferrocene and nickelocene, yielding abundant molecular ions ([M+•]) and protonated species ([(M+H)+]).
- Protonation efficiency is influenced by water presence in the heating gas, allowing for ion population control.
- Efficient in-source CID generates fragment ions, including bare-metal cations and M(cp)+, and HDX reactions confirm metal core involvement in protonation for ferrocene.
Conclusions:
- The HePI source is highly effective for ionizing ferrocene and nickelocene, facilitating detailed mass spectrometric analysis.
- The HePI source enables controlled manipulation of ion formation, including protonation and fragmentation, and in-source chemical reactions like HDX.
- Protonation occurs at the metal core for ferrocene but at peripheral functional groups for derivatives like ferrocene carboxaldehyde and ferrocene boronic acid.
Keywords:
HDXHePIambient ionizationferrocenehelium-plasma ionizationhydrogen−deuterium exchangemetallocenesnickeloceneorganometallicMore Related Videos
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