Mechanistic aspects of the gas-phase reactions of halobenzenes with bare lanthanide cations: a combined experimental/theoretical investigation.

The gas-phase reactions of chlorobenzene with all atomic lanthanide cations Ln(+) (except Pm(+) ) have been investigated by using Fourier transform ion cyclotron resonance mass spectrometry in conjunction with density functional theory calculations. According to the latter, a direct chlorine transfer to the lanthanide cation, which has been observed previously for fluorine abstraction from fluorobenzene, is not operative for the C6 H5 Cl/Ln(+) couples; rather, chlorine transfer proceeds through an initial coordination of the lanthanide cation to the aromatic ring of the substrate. Both, the product distribution and the chlorine abstraction efficiencies are affected by the bond dissociation energy (BDE(Ln(+) Cl)) as well as the promotion energies of Ln(+) to attain a 4f(n)  5d(1)  6s(1) configuration. In addition, mechanistic aspects of some CH and CC bond activations are presented. Where appropriate, comparison with the previously studied C6 H5 F/Ln(+) systems is made.