The [CH2 = CHOH/H2O]+˙ system: A theoretical study of distonic ions,hydrogen-bridged ions and ion–dipole complexes

Several isomeric forms of the vinyl alcohol/water radical cation have been investigated by high-level ab initio molecular orbital theory calculations, including electron correlation effects. Of the ions considered here, the anti form of the ? O ?H ?O? bridged complex is calculated to be the lowest in energy, having a stabilization energy of 100 kJ mol^?1 with respect to the dissociation products CH₂CHOH]⁺˙ and H₂O. Although the isomeric ions may formally be represented as distonic ions, hydrogen-bridged ions and ion–dipole complexes, the only significant barrier separating the isomers appears to be the anti?syn isomerization barrier. However, in the ? O ?H ?O? bridged complex this barrier is found to be considerably lowered relative to the anti?syn isomerization barrier for the free vinyl alcohol radical cation.