The structure of C₅H₅RFe⁺ (R = F, Cl, Br, I, O, OH, OCH₃, C₆H₅, H) ions in the gas phase and the generation of their neutral counterparts by neutralization-reionization mass spectrometry

Abstract

The structure of C5H5FeR(+·) ions was studied by tandem mass spectromerry that included the neutralization-reionization (NR) method. Halogen-containing species (R = F, Cl, Br, I) showed fragmentation that was consistent with a structure that has the cyclopentadienyl ring and R as separate ligands at the metal atom (structure A). This structure also was identified for C5H5FeO(+) and CpFeOH(+·) ions, but these species also easily isomerized to metal-cyclopentadiene structure, RC5H5Fe(+·) (B), followed by hydrogen rearrangement(s) and CO loss. B was the dominant structure of C5H5FeH(+·) and C5H5FeC6H 5 (+·) ions. All ions that have structure A showed recovery signals in their NR mass spectra that indicated that their stable neutral counterparts were generated. The NR mass spectra also provided complementary information about the structure of ions before neutralization and after reionization.

The Generation of Neutral Derivatives of Low-Valence Iron, RFe(I), by Netralization—Reionization Mass Spectrometry

“…Electron ionization of both compounds produced abundant C 5 H 5 FeOH + ions further dissociating with a loss of the cyclopentadienyl ring and giving rise to HOFe + ions. 46 NR mass spectra of HOFe + ions generated from the two different precursors were qualitatively similar to each other. Strong recovery signals were detected in both cases.…”

“…Iron amide ions were generated from ferrocenyl carbamide, C 5 H 5 FeC 5 H 4 CONH 2 . 46 The NR mass spectrum of H 2 NFe + ions (Figure 4) resembled that of CH 3 Fe + 41 and HOFe + ions. The detection of moderately abundant survivor ions clearly indicated the intrinsic stability of the corresponding neutral, H 2 NFe, in the experimental time frame.…”

“…The most prominent dissociation of metastable and collisionally-activated CH 3 C 5 H 4 Fe + ions is the formation of HFe + cations. 46 The major isotope peak of the HFe + ion appears at m/z 57. A peak at m/z 57 also corresponds to 57 Fe + ions; Fe + ions are always present in 70 eV mass spectra of Fe-containing complexes.…”

“…The dissociation of C 5 H 5 FeF + ions provides the major source for these ions. 46 Iron fl uoride ions present another case when isobaric interference complicated the interpretation of the neutralization-reionization experiment. The NR mass spectrum of ions at m/z 75 displayed several peaks that could not be formed from 56 FeF + ions.…”

“…Phenyl iron(I) ions were produced by electron ionization of benzoylferrocene, C 5 H 5 FeC 5 H 4 COC 6 H 5 . 46 was evident due to the presence of a signifi cant recovery peak in the NR mass spectrum ( Figure 6). The two most intense signals in the NR mass spectrum corresponded to Fe + and C 6 H 5 + ions.…”