Evidence for Cyclic Bromonium /ons l. NMR Studies(cont'd 5S02 Me Not observed Me SbF5 So2 Open chlorocarbonium ion has long range coupling thru sp" cationic cente No long range coupling observed in the bromonium case implies a cyclic bridged intermediate No13c data is given for the chloro-version a 1c data(variable temp. for bromonium gives evidence for an equilibrium process. This low temp. study suggests that the intermediate is mainly a static bridged ion in equilibrium with a ll amount of B-haloalkyl carbonium ion A J Am. chem. soc. 1969. 91 A J. Am. Chem PA-Bromonium 05 10/4/00 2: 44 PMCH3 CH2 CH3 CH2 Olah, G. A. J. Am. Chem. Soc. 1969, 91, 5801 Olah, G. A. J. Am. Chem. Soc. 1974, 96, 3565 . Open chlorocarbonium ion has long range coupling thru sp2 cationic center No long range coupling observed in the bromonium case implies a cyclic bridged intermediate No 13C data is given for the chloro-version 13C data (variable temp.) for bromonium gives evidence for an equilibrium process. This low temp. study suggests that the intermediate is mainly a static bridged ion in equilibrium with a small amount of β -haloalkyl carbonium ion. Evidence for Cyclic Bromonium Ions I. NMR Studies (cont'd) ii. Unsymmetrical Case: . . . + SbF5 SO2 + Not observed SbF5 SO2 + + Me Cl Me Cl Me Me Me Me Cl H H H H Cl Me Me Br H Br H Br Me Me Me Me Br H H 09A-Bromonium 05 10/4/00 2:44 PM