Ab initio molecular orbital calculations on acetyl cations. Relative hyperconjugative abilities of C-X bonds

Abstract

Ab initio molecular orbital calculations have been carried out for the substituted acetyl cations RCO⁺ (R = CH₃, CH₃CH₂, (CH₃)₂CH, (CH₃)₃C) and XCH₂CO⁺ (X = CH₃CH₂, CH₂=CH,CH=C, C=N, OH, F). The stabilities of the ions RCO⁺ are found to follow the normal inductive order of the substituents R. The calculations suggest that C-C hyper-conjugation is more effective than C-H hyper-conjugation.