title: Structure, conformation, and dynamic processes of the stereolabile atropisomers of hindered terphenyl hydrocarbons.
abstract: [reaction: see text] 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.
authors.affiliation: Department of Organic Chemistry A. Mangini, University of Bologna, viale Risorgimento 4, Bologna I-40136, Italy.
authors.forename: Lodovico
authors.initials: L
authors.lastname: Lunazzi
authors.forename: Andrea
authors.initials: A
authors.lastname: Mazzanti
authors.forename: Mirko
authors.initials: M
authors.lastname: Minzoni
authors.forename: J Edgar
authors.initials: JE
authors.lastname: Anderson