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Circular Dichroism and TDDFT Investigation of Chiral Fluorinated Aryl Benzyl Sulfoxides
Author(s) -
Berardozzi Roberto,
Guido Ciro A.,
Capozzi Maria Annunziata M.,
Cardellicchio Cosimo,
Di Bari Lorenzo,
Pescitelli Gennaro
Publication year - 2015
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201500648
Subject(s) - chemistry , time dependent density functional theory , circular dichroism , aryl , sulfoxide , computational chemistry , conformational isomerism , density functional theory , thioanisole , atomic orbital , excited state , crystallography , photochemistry , molecule , organic chemistry , atomic physics , physics , quantum mechanics , alkyl , catalysis , electron
A series of ten chiral aryl benzyl sulfoxides with perfluorinated aryl or benzyl rings, obtained by enantioselective oxidation of sulfides, has been investigated by means of electronic circular dichroism (ECD) spectroscopy and time‐dependent DFT (TDDFT) calculations. The (per)fluorination of the aromatic rings has a large impact on the conformer population, the molecular orbitals shape, and the character of electronic transitions. In this series, the transition responsible for the “sulfoxide primary” CD band has a large charge transfer (CT) character, as demonstrated by the CT metric index Γ NTO . As a consequence, global DFT hybrids such as B3LYP are largely inaccurate in the prediction of excited states; nevertheless, a correct simulation of CD spectra may be achieved by using range‐separated functionals such as CAM‐B3LYP. The use of the empirical Mislow's rule for assigning the absolute configuration is strongly discouraged for this class of compounds.