Structure, conformation, and dynamic processes of the stereolabile atropisomers of hindered terphenyl hydrocarbons.
[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.
Lunazzi
Lodovico
L
Department of Organic Chemistry A. Mangini, University of Bologna, viale Risorgimento 4, Bologna I-40136, Italy.
Mazzanti
Andrea
A
Minzoni
Mirko
M
Anderson
J Edgar
JE