Stimulus-responsive metallocenes: a photo/thermal switch enabled by the perfluorinated Cp* ligand.
Robin Sievers1, Nick Hartmann1, Paulin S Riemann1
1Freie Universität Berlin, Institut für Chemie und Biochemie - Anorganische Chemie Fabeckstraße 34/36 14195 Berlin Germany moritz.malischewski@fu-berlin.de.
Chemical Science
|June 5, 2025
Summary
Researchers synthesized new ferrocene and ruthenocene complexes. Photolysis revealed reversible cyclopentadienyl ligand dissociation, a novel light and heat-initiated reaction in organometallic chemistry.
Area of Science:
- Organometallic Chemistry
- Photochemistry
- Coordination Chemistry
Background:
- Electron-deficient metallocenes featuring perfluorinated cyclopentadienyl (Cp*) ligands are of interest.
- Understanding ligand substitution lability is crucial for catalyst design.
Purpose of the Study:
- To synthesize and characterize analogous ferrocene and ruthenocene complexes with Cp* ligands.
- To investigate the substitution lability of the Cp* ligand under photolytic conditions.
- To explore the reactivity of resulting complexes and the reversibility of ligand dissociation.
Main Methods:
- Synthesis and full characterization of [Fe(C5H5)(C5(CF3)5)] and [Ru(C5H5)(C5(CF3)5)].
- Photolysis experiments in acetonitrile (MeCN) to induce ligand substitution.
- Trapping reactions with chelating diphosphine (DPPE) to stabilize intermediates.
- Spectroscopic and analytical techniques for characterization.
Main Results:
- Successful synthesis of bench-stable ruthenocene [Ru(C5H5)(C5(CF3)5)].
- Photolysis generated reactive piano-stool complexes [M(C5H5)(MeCN)3][C5(CF3)5] (M = Fe, Ru) via Cp* ligand dissociation.
- The iron complex underwent dismutation, but was trapped as [Fe(C5H5)(DPPE)(MeCN)][C5(CF3)5].
- The ruthenium complex exhibited a thermally reversible backreaction to the parent ruthenocene.
Conclusions:
- The Cp* ligand can dissociate reversibly under mild conditions initiated by light.
- This work demonstrates the first example of light- and heat-induced reversible cyclopentadienyl ligand dissociation and recoordination.
- The findings open new avenues for controlling reactivity in organometallic complexes.
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