Structure and stability of halonium cations of cycloalkenes. A theoretical study

A theoretical study of the chloronium and bromonium cations of cyclopropene, cyclobutene, cyclopentene and cyclohexene, C3H4X+, C4H6X+, C5H8X+ and C6H10X+, have been studied at the ab initio MP2 and density functional B3LYP levels of theory implementing 6-311++G(d,p) basis set. The potential energy surfaces of all molecules under investigation have been scanned and the equilibrium geometries and their harmonic vibrational frequencies have been calculated. The computed hydride affinities of all conformers found and the NICS for the bridged cations show that the bromo cations are more stable than the analogous chloro cations, with the bridged 1,4-bromocyclohexyl cation being the most stable cation species studied.