Dr. Marian Olaru, Alexandra Mischin, Lorraine A. Malaspina, Dr. Stefan Mebs, Prof. Dr. Jens Beckmann

Angewandte Chemie-International Edition (2020) 59, 1581-1584

https://doi.org/10.1002/anie.201913081

The bis(ferrocenyl)phosphenium ion, [Fc₂P]⁺, reported by Cowley et al. (J. Am. Chem. Soc. 1981, 103, 714–715), was the only claimed donor-free divalent phosphenium ion. Our examination of the molecular and electronic structure reveals that [Fc₂P]⁺ possesses significant intramolecular Fe⋅⋅⋅P contacts, which are predominantly electrostatic and moderate the Lewis acidity. Nonetheless, [Fc₂P]⁺ undergoes complex formation with the Lewis bases PPh₃ and IPr to give the donor–acceptor complexes [Fc₂P(PPh₃)]⁺ and [Fc₂P(IPr)]⁺ (IPr=1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene).