American Chemical Society
ol050091a_si_001.cif (22.63 kB)

Structure, Conformation, and Dynamic Processes of the Stereolabile Atropisomers of Hindered Terphenyl Hydrocarbons

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posted on 2005-03-31, 00:00 authored by Lodovico Lunazzi, Andrea Mazzanti, Mirko Minzoni, J. Edgar Anderson
Ortho-substituted p-terphenyl hydrocarbons exist as trans and cis atropisomers that were identified by low-temperature NMR spectroscopy. The interconversion barriers increase with the dimensions of the ortho substituents, the experimental values being matched by ab initio calculations. X-ray diffraction shows that only the trans atropisomer is present in the solids. Spectra of a tert-butyl derivative in nonequilibrium conditions indicate that the cis is more populated than the trans atropisomer in solution, favored by attractive interactions.