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Reflectance circular dichroism of solid-state chiral coordination compounds
Ivano Bilotti1, Paolo Biscarini, Ettore Castiglioni
1Dip. Chimica Fisica ed Inorganica, Università di Bologna, Bologna, Italy.
Chirality
|September 19, 2002
Summary
Solid-state diffuse reflectance circular dichroism (DRCD) successfully obtains reliable spectra for chiral coordination compounds. This method accurately determines absolute configuration and stereochemistry, offering advantages over solution-based techniques.
Area of Science:
- Coordination Chemistry
- Spectroscopy
- Chiroptical Methods
Background:
- Chiral coordination compounds are crucial in various scientific fields.
- Characterizing solid-state stereochemistry often requires specialized techniques.
- Solution-based circular dichroism (CD) can be influenced by solvent and pressure.
Purpose of the Study:
- To validate solid-state diffuse reflectance circular dichroism (DRCD) for chiral coordination compounds.
- To compare DRCD spectra with solution, nujol mull, and KBr pellet spectra.
- To assess DRCD's ability to determine absolute configuration and stereochemistry.
Main Methods:
- Measurement of DRCD spectra for chiral lambda- and delta-M[(A--A)(n)](m+) coordination compounds (M=Cr, Co).
- Comparison of DRCD spectra with solution, nujol mull, and KBr pellet spectra (300-800 nm).
- Analysis of spectral data to correlate with absolute configuration and stereochemistry.
Main Results:
- DRCD spectra were successfully obtained for various chiral coordination compounds.
- DRCD spectra reliably reflected the absolute configuration at the metal center.
- Subtle stereochemical changes were accurately detected in the solid state compared to solution.
Conclusions:
- Solid-state DRCD is a valid and reliable method for obtaining chiroptical spectra.
- DRCD provides accurate stereochemical information without solvent or pressure effects.
- DRCD offers a direct link to X-ray diffractometry structures for randomly oriented samples.