Butonium cations rearrangement

The pulsed electron beam MS technique was also used by Hiraoka and Kebarle842 to study the C4H + cations. In the ion-molecule reaction of ethane and the ethyl cation, two species were observed and identified as the 2-//-n-butoniu m cation 469 and the 2-C-w-butonium cation 470. C—C protonated ion 470 formed first rearranges to C—H protonated ion 469 (energy barrier = 9.6 kcal mol-1) and then dissociation to sec-C4H9+ + H2 takes place. 

An experimental study also exists with respect to the C4H1C cations. Using the pulsed electron-beam MS technique, Hiraoka and Kebarle observed two species in the ion-molecule reaction of ethane and the ethyl cation. They identified them as the 59 2-H-n-butonium and the 60 2-C-n-butonium cation. C-C protonated ion 60 formed first rearranges to C-H protonated ion 59 (energy barrier = 9.6 kcal mol ) before dissociation to xcc-QH/ -1- If. 

Three cations, an //-protonated (471) and two C-protonated (470 and 472) isomers were found by Collins and O Malley831 by DFTand MP2 calculations. Ion 472 is more stable than ion 470 by about 5 kcal mol-1. Eleven stable isomeric protonated butane cations including rotamers were found by extensive studies by Mota and coworkers843 [MP4SDTQ(fc)/6-311++G //MP2(full)6 - 31G level]. The stability order 2-C-w-butonium (470) > 1-C-w-butonium (472) > 2-/7-w-butonium (469) > l-//-/ -butonium (471) was interpreted in terms of charge delocalization in the involved 3c-2e bonds. Cation 471 prefers to rearrange to cation 472, whereas cation... 

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