Density functional study of potential energy surfaces and relative stabilities of halonium cations of ethylene and cyclopentenes

Potential energy surfaces, hydride affinities and nuclear independent chemical shifts (NICS) of a variety of halonium cations of ethylene C2H4X+, cyclopentene C5H8X+ and hydroxy substituted cyclopentenes C5H8−n(OH)nX+ (n=1, 2), where X=Cl and Br were computed at the Becke3LYP/6-311++G(d,p) level of theory. 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, as well as the NICS values for the 1,2-bridged cations indicate that the bromo cations are more stable than the analogous chloro cations.