| The thermal and photochemical reactions of cycloheptene, 1,3- and 1,4-cyclohexadiene with ozone have been studied using a combination of matrix isolation, infrared spectroscopy, and theoretical calculations. The reaction of cycloheptene with ozone resulted in the first observation of early intermediates for a cyclic alkene with conformational isomerism. Spectral evidence supports the presence of the primary ozonide of the chair and boat conformers of cis-cycloheptene, which represents the first time two primary ozonide isomers have been observed for any alkene. In addition, at least one conformer of the Criegee intermediate, as well as stable end products were observed spectroscopically. Experimental and theoretical results for the reaction of ozone with 1,4-cyclohexadiene demonstrate that this reaction does not follow the long-accepted Criegee mechanism. Rather, the reaction of ozone with 1,4-cyclohexadiene leads to the essentially barrierless formation of benzene, C6H6, and H2O3. In addition, it was determined that the reaction of ozone with 1,3-cyclohexadiene follows two pathways, one of which is the Criegee mechanism through a low energy transition state leading to formation of the primary ozonide. With a similar barrier, ozone can also abstracts a single hydrogen from C5 while adding to C1 of 1,3-cyclohexadiene, forming a hydroperoxy intermediate. The study of 1,3- and 1,4-cyclohexadiene presents two of the rare cases in which the Criegee mechanism is not the dominant pathway for the ozonolysis of an alkene as well as the first evidence for dehydrogenation of an alkene by ozone.;The low-energy photochemical reaction of ozone and n-butylferrocene has been studied using a combination of argon-matrix isolation, infrared spectroscopy, and theoretical calculations. The results support the photodissociation of ozone by red light (lambda ≥ 600 nm) which produces an atomic oxygen, (O3P), and a molecular oxygen. (O3P) 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 dark deposition reactions of ozone with ferrocene and with n-butylferrocene were studied using matrix isolation, UV-Vis spectroscopy, and theoretical calculations. The co-deposition of ferrocene with ozone and that of n-butylferrocene with ozone led to production of green charge transfer complexes. These charge transfer complexes underwent photochemical reactions upon irradiation with red light (lambda ≥ 600 nm). The MO analysis of the long wavelength transitions indicated that the formation of the charge transfer complex with ferrocene or n-butylferrocene affects the how readily the pi*-orbital on ozone is populated when red light (lambda ≥ 600 nm) is absorbed. All findings given are supported by 18O-labeled ozone infrared experiments and literature spectra. In addition further justification was provided by theoretical calculations at the B3LYP/6-311++G(d,2p) level. Theoretical UV-Vis spectra were calculated with TD-DFT using a B3LYP functional and the 6-311G++(d,2p) basis set. |
