Quantum Chemical Calculations of the Structure, Property and Stability of Penta-coordinated Carboniu

The structure and energy of the carbonium ions formed upon protonation of butane were studied by the DFT methods. Four stable structures are identified for the protonated form of n-butane, the energy increases in the following order: C2HC3C1HH. The stability of the penta-enordinated carbonium ions may be explained by the electron distribution in the three-center-two-electron bonds. The delocalization of the penta-eoordinated carbonium ion CHC with three-center-two-electron bonds on positive charges was stronger than that of the penta-coordinated carbonium ion CHH with three-center-two-electron bonds and its stability was higher than that of the penta-coordinated earbonium ion CHH with three-center-two-electron bonds.