A Stibenium Stabilized by Intramolecular Coordination from a Phosphine

A bis(ferrocenyl)stibenium with intramolecular phosphine coordination was obtained as an air-stable compound after abstracting bromide from the corresponding bromostibine. UV-vis spectroscopy measurements and DFT calculations revealed that this stibenium exhibits ligand-to-metal charge-transfer absorption bands that arise from the electron transfer from the ferrocenyl moieties to the Sb center, suggesting high electrophilicity for the latter. The redox behavior of the isolated stibenium was investigated by cyclic-voltammetry measurements, which revealed irreversible oxidation behavior.