ELECTRON-TRANSFER REACTIVITY IN THE ACTIVATION OF ORGANIC FLUORIDES BY BARE METAL MONOCATIONS

In the gas phase, the bare calcium monocation reacts with organic fluo rides, via C-F bond activation to yield CaF+ together with the corresp onding radical. Ab initio calculations are used to analyse the mechani sm of reaction with fluoromethane, Density-functional calculations lea d to underestimated reaction barriers, whereas ACPF and CCSD(T) calcul ations with large basis sets provide good agreement with experiment. T he reaction involves a tightly bonded TS in which an electron is trans ferred from calcium to carbon; this structured harpoon mechanism highl ights the simultaneous importance of electron transfer and of metal-fl uorine bonding in reductive defluorination processes. (C) 1997 Elsevie r Science B,V.