Resonance Raman Spectra of Dioxygen Adducts of Cobalt Porphyrins. Spectroscopic Manifestation of Vibrationally Coupled Dioxygen and Energy Matching of Interactive Modes

Article abstract of DOI:10.1021/ja00222a009

Resonance Raman spectra of dioxygen adducts of cobalt porphyrin complexes with 3,5-dichloropyridine (DCP) are reported.When 16O2, 18O2, and scrambled oxygen (i.e., 16O2:16O18O:18O2) are used, evidence is obtained for vibrational coupling of ν(O-O) with an internal mode of axially coordinated DCP.This coupling is manifested spectroscopically by shifts of the coupled modes from their inherent frequencies and/or by intensity enchancement of the coupled internal mode relative to noncoupled ligand modes.The magnitude of the perturbation is shown to be dependent upon energy matching of the interacting modes through a series of studies in wich the frequency of the ν(O-O) is varied by controlled alterations in structure and solution enviroment.