Abstract: The rotation barriers (5.2-8.5 kcal/mol) of the trifluoromethyl group and the chemical shifts of the individual fluorines have been measured by analysis of the variable temperature fluorine nmr spectra of 2, 2-dichlorohexafluoropropane (l), 2, 2- dibromohexafluoropropane (2), 2-iodo-2-(trifluoromethyl) hexafluoropropane (4), 1, 1, 1- trifluoro-2, 2-dichloro-2-iodoethane (5), pentafluoroiodoethane (a), and l, l, l- ...