Proponium ions cation

Two isomeric proponium ions, cation 455 and 457 were computed by Collins and O Malley831 (DFTand MP2 calculations). The 2-//-protonated cation 456, in turn, was suggested to be rather the transition state for the interconversion of the ions. Structure 456 is better described as the van der Waals complex of, vec-C3H7+ and H2, which was already suggested by Hiraoka and Kebarle.748 Mota and co-workers832 have recently... 

Ab initio topological analysis of the proponium cations showed that the most stable structure is the C-proponium ion lying, however, only 0.3 kcal mol below the van der Waals complex of isopropyl cation and H2 (MP4/6-311-H-G / MP2/6-31G level of theory). Similar topological studies of the stability of the different n-butonium cations formed by the protonation of the nonequivalent bonds of n-butane indicated the MP2 level stability order... 

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