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Identification of a Two-Coordinate Iron(I)-Oxalate Complex
Martin Mayer1, Nina Vankova2, Ferdinand Stolz3
1Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstr. 2, 04103, Leipzig, Germany.
Angewandte Chemie (International Ed. in English)
|January 28, 2022
Summary
Researchers discovered unusual iron oxidation state +I in iron-oxalate complexes using mass spectrometry. This finding expands our understanding of iron
Area of Science:
- Chemistry
- Inorganic Chemistry
- Spectroscopy
Background:
- First-row transition metals exhibit exotic oxidation states, prompting significant research interest.
- Iron-oxalate complexes are crucial in various chemical processes and warrant detailed oxidation state investigation.
Purpose of the Study:
- To investigate the oxidation states of iron within iron-oxalate complexes.
- To identify and characterize unusual oxidation states of iron beyond the common +II and +III states.
Main Methods:
- Utilized infrared (IR) free liquid matrix-assisted laser desorption/ionization (MLDI) and ionspray mass spectrometry (IS-MS).
- Employed IR photodissociation spectroscopy to measure vibrational spectra of gas-phase anionic iron oxalate complexes.
- Assigned complex structures by comparing experimental spectra with anharmonic vibrational spectra calculated using second-order perturbation theory.
Main Results:
- Successfully detected iron in its uncommon oxidation state +I, alongside the common +II and +III states.
- Observed iron +I in both positive-ion and negative-ion modes, indicating its stability.
- Measured and assigned vibrational spectra for key anionic complexes: [Fe(III)(C2O4)2]-, [Fe(II)(C2O4)CO2]-, and [Fe(I)(C2O4)]-.
Conclusions:
- Demonstrated the existence and detectability of iron in the +I oxidation state within iron-oxalate complexes.
- Provided structural insights into iron oxalate complexes through vibrational spectroscopy and theoretical calculations.
- Expanded the known chemistry of iron by confirming an unusual oxidation state in a relevant complex system.
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