Iron-nitrosyl complexes formed in zeolites

Infrared photodissociation spectroscopy of iron nitrosyl cation complexes: Fe(NO)n⁺ (n = 1-5)

Infrared spectra of mass-selected mononuclear iron nitrosyl cations Fe(NO)n(+) with n = 1-5 and their argon tagged complexes are measured via infrared photodissociation spectroscopy in the nitrosyl stretching frequency region in the gas phase. The structures are established by comparison of the experimental spectra with the simulated spectra derived from density functional calculations. Two IR active bands were observed for the argon-tagged Fe(NO)2(+) and Fe(NO)3(+) complexes, consistent with theoretical predictions that these complexes have bent C(2v) and nonplanar C(3v) symmetry, respectively. The Fe(NO)4(+) complex was characterized to have a completed coordination sphere with 17 electrons containing a bent one-electron NO ligand and three three-electron NO ligands. The Fe(NO)5(+) complex was determined to involve a Fe(NO)4(+) core ion that is solvated by an external NO molecule.

Study of the Influence of Water on Oxidative Properties of Fe3+ in ZSM-5 Zeolite Channels

The interactions of phenol and thiophene with Fe3+ ions have been studied in ZSM-5 zeolite channels in the presence of water. The Fe-ZSM-5 was prepared by the ion exchange of Fe3+ for Na+. The Fe3+ ions in zeolite channels have unsaturated co-ordination spheres and oxidize organic substrates (phenol, thiophene) at room temperature. The interaction of Fe3+ with phenol gives rise to the stabilized cation-radical PhOH•+ and thiophene forms low oligomers (2-6 monomeric units). The oligomers are present in the neutral as well as oxidized form as cation-radicals (polarons). The formation of dications (bipolarons) has not been observed.