Coexistence of Metallocene Cations and Anions

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry

Background:

• Metallocene complexes are crucial in catalysis and materials science.
• Understanding the electronic and structural properties of metallocene anions is key to expanding their applications.

Purpose of the Study:

• To synthesize and structurally characterize a novel rhodocene anion.
• To investigate the coexistence of metallocene cations and anions in different oxidation states.
• To provide the first structural data for a 4d metallocene anion.

Main Methods:

• Synthesis of the rhodocene anion [Rh(C5Me5)(C5(CF3)5)]− as a [Co(C5Me5)2]+ salt.
• Reduction of the rhodocenium cation [Rh(C5Me5)(C5(CF3)5)][BF4] using decamethylcobaltocene.
• Single-crystal X-ray diffraction (XRD) for structural characterization.
• 103Rh NMR spectroscopy to analyze electronic changes upon reduction.

Main Results:

• Successfully synthesized and characterized the rhodocene anion [Rh(C5Me5)(C5(CF3)5)]−.
• Observed an unprecedented coexistence of metallocene cations and anions in different oxidation states.
• Determined the structure of the 4d metallocene anion, revealing an η3-bound perfluorinated ligand in the Rh(I) state.
• NMR data showed significant shifts indicating changes in the electronic environment of the rhodium center.

Conclusions:

• The study presents the first structurally characterized 4d metallocene anion.
• The bonding mode of the perfluorinated ligand adjusts to satisfy the 18-electron rule in the reduced state.
• This work expands the understanding of metallocene chemistry, particularly for anionic species.