Stable C2H5X+˙ (X=Cl, Br) radical cations of structure [CH3CHXH+˙]: Their energetics and dissociation characteristics

Abstract A new radical cation having the methyl carbene type structure [CH 3 CHClH] +˙ has been characterized in the gas phase. It is readily generated by the dissociative ionization [CH 3 CHCICO 2 H] +˙ → CO 2 +[CH 3 CHCIH] +˙ . Its enthalpy of formation has been estimated to be 951 kJ mol −1 , close to that of [CH 3 CH 2 CI] +˙ . The principal fragmentation characteristics (loss of HCl and Cl ˙ ) of the ion are discussed. A brief description of the bromo analogue [CH 3 CHBrH] +˙ is also given.