Polarized x-ray absorption near-edge structure of highly oxidized chromium porphyrins
Polarized X-ray absorption near-edge spectra have been measured for Cr/sup IV/(TTP)O and Cr/sup V/(TTP)N (TTP is the dianion of 5,10,15,20-tetra-p-tolylporphyrin). These spectra, which are very similar for the two molecules, show an intense preedge absorption feature polarized perpendicular to the porphyrin plane. The absorption edges are relatively featureless when the polarization is parallel to the porphyrin plane. On the basis of multiple-scattered-wave X..cap alpha.. calculations, the intense preedge feature is interpreted as a bound ..-->.. bound transition with significant metal character in the excited state. This transition, which has been observed in many metal-oxo species, was not observed in the putative ferryl (Fe=o) intermediates of horseradish peroxidase. The reasons for this absence in Fe=O species and its relationship to the reactivity of metal-oxo porphyrin complexes are discussed in light of the present results.
- Research Organization:
- Stanford Univ., CA
- OSTI ID:
- 5454573
- Journal Information:
- Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 25:13; ISSN INOCA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400600* -- Radiation Chemistry
ANIONS
BREMSSTRAHLUNG
CALCULATION METHODS
CARBOXYLIC ACIDS
CHARGED PARTICLES
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
CHROMIUM COMPLEXES
COMPLEXES
DATA
ELECTROMAGNETIC RADIATION
ELECTRONIC STRUCTURE
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
IONS
NONDESTRUCTIVE ANALYSIS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDATION
PORPHYRINS
RADIATIONS
SYNCHROTRON RADIATION
TRANSITION ELEMENT COMPLEXES
X-RAY EMISSION ANALYSIS