Gas-phase reactions of the dichlorocarbene radical cation

The gaseous dicklorocarbene radical cation is reported to behave as a highl y reactive electrophile rather than a radical toward various organic substr ates in a Fourier-transform ion cyclotron resonance mass spectrometer. For example, the carbene ion reacts with alkyl halides (R-X) via fast electroph ilic addition to form a covalently bonded, internally excited intermediate Cl2C-X-R+.. The intermediate fragments either homolytically or heterolytica lly to produce net halogen atom or halide ion transfer products, respective ly. The observed ionic reaction product is determined by the ionization ene rgies of the Two possible neutral Fragments (CCl2X.. and R-.). The fragment with the lower ionization energy preferentially retains the charge. Most r eactions observed for heteroatom-containing organic compounds also appear t o follow this electrophilic addition-elimination mechanism. In some cases, addition of carbonyl compounds to the carbene ion is followed by homolytic cleavage of the C-Q bond to yield a new carbene radical cation.