posted on 2005-03-31, 00:00authored byLodovico 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.