Date of Award

Fall 1990

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Chemistry

Abstract

Resonance Raman (RR) spectra were obtained on model compounds representing intermediates in the reaction cycle of cytochrome P-450. Spectra of the dioxygen adduct, FeI I (TpivPP) (C - + 6HF4s ) (02)K 18c6, reveal an oxygen sensitive band at 532cm-1 which shifts to 499cm-1 upon 18o2 substitution. The location of this band and its sensitivity to isotopic substitution led to the assignment of the 532cm- 1 band as the v(Fe-0) stretching frequency. Other dioxygen adducts were prepared using different thiolate bases (e.g. C6F5S-, 2-C6H4ClS-, 3-C6H4ClS-, 2,6-C6H3Cl2S-, and 3,4- c6H3cl2S-) to determine their effect on the v(0-0) and v(Fe- 0) vibrational frequencies. The changes of the v(0-0) frequencies upon base substitution were small. The v(Fe-0) frequencies were difficult to detect due to the inherent weakness of this vibrational mode. Resonance Raman spectra were also obtained for, FeiV(TMP")=O+, a ferryl porphyrin pi-cation radical, and an oxygen isotope sensitive band was observed at 802cm-1 . Its location, along with a 35cm-1 shift when oxygen-18 substituted m-chloroperoxybenzoic acid (mCPBA) was used as the oxidizing agent, prompted assignment of the 802cm-1 band to the v(Fe-0) stretch of the ferryl porphyrin pi-cation radical. A previous paper by Kitagawa and co-workers stated that the v ( Fe-o) stretch for FeiV (TMP") =0+ in a methylene chloride/methanol mixed solvent occurred at 828cm-1 . Experiments at low and high laser powers were performed which showed that the 828cm-1 band is associated with a photoproduct.

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