Magnetically Induced Binary Ferrocene with Oxidized Iron

Ferrocene is perhaps the most popular and well-studiedorganometallicmolecule, but our understanding of its structure and electronic propertieshas not changed for more than 70 years. In particular, all previousattempts of chemically oxidizing pure ferrocene by binding directlyto the iron center have been unsuccessful, and no significant changein structure or magnetism has been reported. Using a metal organicframework host material, we were able to fundamentally change theelectronic and magnetic structure of ferrocene to take on a never-beforeobserved physically stretched/bent high-spin Fe(II) state, which readilyaccepts O-2 from air, chemically oxidizing the iron fromFe(II) to Fe(III). We also show that the binding of oxygen is reversiblethrough temperature swing experiments. Our analysis is based on combiningMo''ssbauer spectroscopy, extended X-ray absorption finestructure, in situ infrared, SQUID, thermal gravimetric analysis,and energy dispersive X-ray fluorescence spectroscopy measurementswith ab initio modeling.

Automated summary

Ferrocene, a well-known organometallic molecule, has had its structure and electronic properties unchanged for over 70 years. However, through the use of a metal organic framework host material, researchers were able to alter the electronic and magnetic structure of ferrocene, giving it a unique physically stretched/bent high-spin Fe(II) state that readily accepts O-2 to chemically oxidize the iron from Fe(II) to Fe(III). The binding of oxygen was found to be reversible through temperature swing experiments. The study combined various measurement techniques and ab initio modeling.