Photochemistry of metalloporphyrins
During the current period our efforts have been focussed on the characterization of porphyrin radical cations, anions, and excited states, and of oxo-metal prophyrins, using resonance Raman (RR) spectroscopy. RR spectra of octaethyl porphyrin and tetraphenylporphyrin radical cations showed different frequency shift patterns, which were interpreted in terms of the expected behavior of a{sub 1u} and a{sub 2u} radicals. Anomalously polarized RR bands were discovered whose frequencies and isotope shifts differed greatly from those of the neutral parents, and which signalled pseudo-Jahn-Teller activity in A{sub 2g} modes which mix the A{sub 1u} and A{sub 2u} ground and low-lying excited states. The RR spectrum of the ZnTPP radical anion showed modest frequency downshifts in Jahn-Teller (J-T) active B{sub 1g} and B{sub 2g} modes, but no significant polarized scattering from these modes, indicating that the J-T effect is dynamic in character. Manganyl porphyrins were found to have anomalously low metal-oxo stretching frequencies, and the weakness of the bond was related to electronic properties of the d{sup 3} Mn(IV) ion and its interactions with the porphyrin orbitals. Vanadyl porphyrins were used to assess the influence of solvents and axial ligands and of the effects of porphyrin radical cation formation on the metal-oxo bond. 13 refs.
- Research Organization:
- Princeton Univ., NJ (USA). Dept. of Chemistry
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- FG02-88ER13876
- OSTI ID:
- 6188754
- Report Number(s):
- DOE/ER/13876-1; ON: DE91009136
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
ABSORPTION
ANIONS
AROMATICS
CARBOXYLIC ACIDS
CATIONS
CHARGED PARTICLES
CHLORINS
COMPLEXES
DOCUMENT TYPES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IONS
IRON COMPLEXES
JAHN-TELLER EFFECT
LASER SPECTROSCOPY
MANGANESE COMPLEXES
NITROSO COMPOUNDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHENOLS
POLYPHENOLS
PORPHYRINS
PROGRESS REPORT
RADICALS
RAMAN SPECTROSCOPY
RESONANCE ABSORPTION
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES
VANADIUM COMPLEXES
ZINC COMPLEXES