An iron-carbonyl derivative of C60 examined with Moessbauer spectroscopy

Abstract

Moessbauer measurements performed between 5 and 300 K on polycrystalline powder of an iron-carbonyl derivative of C[sub 60] reveal two inequivalent iron sites. The first site displays a quadrupole split doublet at all temperatures, assigned to an [(Fe(CO)[sub 4])[sub x]([eta][sup 2]-C[sub 60])] adduct (x unknown). This iron site presents an S = O spin state and a negative isomer shift indicating that C[sub 60] acts as an electron pair donor to the metal center. The average effective hyperfine field for the second site is characteristic of an Fe(III) high-spin (S = 5/2) state and exhibits relaxation effects. This Fe(III) sextet splits into two subspectra, on the application of a magnetic field, which can be assigned to the octahedral and tetrahedral sites of [gamma]-Fe[sub 2]O[sub 3] microparticles formed on the grain surface. 14 refs., 3 figs., 1 tab.