The reaction of N(S-4) with CH2F: A comparative ab initio and DFT study

The triplet potential energy surface for the N(S-4) + CH2F((2)A') reaction has been studied employing both MP2 and DFT(B3LYP) methods. The energies of the involved species have been refined using the G2, CBS, and CCSD(T) meth ods, respectively. The general picture for this reaction is a typical addit ion-elimination mechanism, where initially a rather stable intermediate, (N CH2F)-N-. ., is obtained by the interaction of nitrogen with the radical th rough the carbon atom. There are two preferred products from the thermodyna mic viewpoint, trans-FC.=NH and HFC=N-., the latter one being slightly more stable. Other possible products, such as H2C=N-. and trans-HC.=NH, are als o exothermic but less stable, whereas cis-HC.=NF is even clearly endothermi c. From the kinetic viewpoint, HFC=N-. is predicted to be the preferred pro duct. It seems that neither isomerization nor subsequent elimination of hyd rogen or fluorine atoms from the primary products is feasible, since all th ese processes are much less exothermic and involve considerable kinetic bar riers.