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

• Molecular complex between ozone and n-butylferrocene isolated.
• Long wavelength (λ > 600 nm) photodissociation of ozone carried out, leading to O(3P) reaction with n-butylferrocene
• Multiple intermediate oxidation products observed and supported computationally.
• Overall reaction mechanism proposed and calculated theoretically.

The photochemical reaction of ozone and n-butylferrocene has been studied using a combination of argon-matrix isolation, infrared spectroscopy, and theoretical calculations. The dark deposition produced a vivid green matrix that, when irradiated with red light, turned a brownish-red color. This green matrix as well as slightly red-shifted O3 infrared absorptions are indicative of the formation an initial charge transfer complex between ozone and n-butylferrocene. The spectral results support the photodissociation of the complexed ozone with red light (λ ≥ 600 nm) producing an oxygen atom, O(3P), and a dioxygen molecule, O2(3Σ). The O(3P) then reacts with n-butylferrocene to form products consisting of an iron atom with a coordinated n-butylcyclopentadienyl or cyclopentadienyl ring and either: (1) a pyran, (2) an aldehyde, or (3) a bidentate cyclic aldehyde with a seven-membered ring including the iron atom. The photochemical products were characterized with FT-IR spectroscopy, 18O-labeled O3 experiments, and DFT calculations using the B3LYP functional with the 6–311++G(d, 2p) basis set. A possible mechanism for the photochemical reaction is discussed.