Infrared Matrix-Isolation and Theoretical Studies of the Reactions of Ferrocene with Ozone

Abstract

The reactions between ferrocene (Cp2Fe) (2a) and ozone (O3) were studied using low-temperature matrix-isolation techniques coupled with theoretical density functional theory (DFT) calculations. Co-deposition of Ar/Cp2Fe and Ar/O3 gas mixtures onto a cryogenically cooled CsI window produced a dark-green charge-transfer complex, Cp2Fe-O3, that photodecomposed upon red (λ ≥ 600 nm) and infrared (λ ≥ 1000 nm) irradiation but was stable to green or blue irradiation. Products of photodecomposition were characterized by FT-IR, oxygen-18 labeling, and DFT calculations using the B3LYP functionals and the 6-311G++(d,2p) basis set. Likely, photochemical products included four structures having the molecular formula C10H10FeO, identified by DFT calculations based on their calculated infrared spectra and (18)O isotope shifts. Each of these calculated molecules had one intact and fully coordinated η(5)-C5H5 cyclopentadienyl (Cp) ring and (1) an η(5)-C5H5O cyclic ether (pyran ring) (2b), (2) an η(4)-C5H5O linear aldehyde (2c), (3) a bidentate cyclic aldehyde with a seven-membered ring including the iron atom (2d), or (4) an Fe-O bond and an η(2)-C5H5 (Cp) ring (2e). No conclusive evidence for a gas-phase thermal reaction between ferrocene and ozone was observed under the conditions of these experiments. However, strong evidence for a surface-catalyzed thermal reaction was observed in merged-jet experiments wherein the gases were premixed before deposition. Surface-catalyzed ferrocene-ozone reaction products included a thin film of Fe2O3 observed on the walls of the merged tube as well as cyclopentadiene (C5H6), cyclopentadienone (C5H4O), and further oxidation products observed in the matrix. Possible mechanisms for both the photochemical and the thermal reactions are discussed.

Charge-Transfer Complexes and Photochemistry of Ozone with Ferrocene and n-Butylferrocene: A UV–vis Matrix-Isolation Study

“…This resulted in the observation of a green matrix, as has been seen and previously reported in the infrared studies. 12,13 While some changes relative to the blank were visibly apparent, difference spectra (also shown in Figure 1a) clearly revealed a new broad A similar set of experiments was conducted involving the twin jet dark codeposition of samples of Ar/O 3 and Ar/n-butyl cp 2 Fe to mirror the parallel infrared studies. The results for this system were comparable to the O 3 /cp 2 Fe system with some red shifting, with a broad absorption centered at 816 nm, a second product peak at 382 nm, and a shoulder at 328 nm as shown in Figure 1b.…”

“…12 The only new feature noted was a slightly perturbed antisymmetric stretching mode of O 3 , which shifted a few wavenumbers to the red of parent O 3 . This shift is characteristic of the formation of a molecular complex between O 3 and cp 2 Fe, and it suggested that the green color the matrix might be due to a molecular complex.…”

Long wavelength photochemistry of ozone and n-butylferrocene: A matrix isolation study

“…This phenomenon was also observed in the Ar/O 3 /cp 2 Fe experiments. 23 All further experiments were performed by covering the cell windows during deposition.…”

“…The nickel ferrite thin film is of particular interest due to its potential for application in microelectronic devices. 22 Recently a matrix isolation study of the reaction of ferrocene (cp 2 Fe) and ozone (O 3 ) was conducted by Kugel et al 23 This study used matrix-isolation combined with IR spectroscopy and theoretical calculations to show that a photochemical reaction of O 3 with cp 2 Fe occurs upon irradiation with red light (λ ≥ 600 nm). Thislow-energyphotochemical reaction leads to the production atomic oxygen O( 3 P) which subsequently reacts with cp 2 Fe resulting in the formation of an iron cyclopentadienyl ring moiety and ether: (1) a pyran, (2) an aldehyde, or (3) a bidentate cyclic aldehyde with a seven-membered ring including the iron atom.…”

Iron‐Promoted CC Bond Formation in the Gas Phase

“…[7] As aw hole,t he nature of the products obtained in the reactions of (h 5 -C 5 H 5 )Fe + indicates that, irrespective of the coordination site of the added nucleophile,t he coordination of the iron with the carbon ring is always preserved. [8] Although the process is promising for solar energy conversion devices,s of ar no evidence for thermal reactions has been found. [8] Although the process is promising for solar energy conversion devices,s of ar no evidence for thermal reactions has been found.…”