Spectroscopic characterization of lanthanide octaethylporphyrin sandwich complexes. Effects of strong. pi. pi. interaction

Optical absorption and resonance Raman spectra are reported for the lanthanide sandwich porphyrins, Eu{sup III}(OEP){sub 2}, Nd{sup III}(OEP){sub 2}, and La{sup III}(OEP){sub 2} (OEP = octaethylporphyrin). These complexes contain a single hole in the porphyrin {pi} system and are electronically simi...

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Bibliographic Details
Published in:Journal of the American Chemical Society 1990-04, Vol.112:9
Main Authors: Duchowski, J.K., Bocian, D.F.
Format: Article
Language:English
Subjects:
ABSORPTION SPECTRA
CARBOXYLIC ACIDS
COMPLEXES
DATA
DATA ANALYSIS
EUROPIUM COMPLEXES
EXPERIMENTAL DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
LANTHANUM COMPLEXES
MEASURING INSTRUMENTS
MEASURING METHODS
NEODYMIUM COMPLEXES
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PORPHYRINS
RAMAN SPECTRA
RARE EARTH COMPLEXES
SPECTRA 400500 > Photochemistry
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Summary:Optical absorption and resonance Raman spectra are reported for the lanthanide sandwich porphyrins, Eu{sup III}(OEP){sub 2}, Nd{sup III}(OEP){sub 2}, and La{sup III}(OEP){sub 2} (OEP = octaethylporphyrin). These complexes contain a single hole in the porphyrin {pi} system and are electronically similar to the Ce{sup IV} sandwich porphyrin cation radical Ce{sup IV}(OEP){sub 2}{sup +}. Variable-temperature (10-300 K) UV-vis and near-infrared (NIR) spectra are obtained for all four single-hole sandwiches. At high resolution and/or at low temperatures, well-resolved fine structure is observed on the intradimer charge-transfer bands (ca. 1,250 nm) of all the complexes. The absorption is dominated by a single Franck-Condon active vibration. This vibration is assigned as a mode, Q{sub AB}, which contains a significant amount of multicenter character and modulates interring separation. Vibronic analysis of the NIR band contours reveals that two system origins, separated by 400-700 cm{sup {minus}1} (depending on the complex), are present. The progressions built off the lower and higher energy origins exhibit spacings of {approximately} 250 and {approximately} 315 cm{sup {minus}1}, respectively.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja00165a009