Theoretical Study On The Nucleophilic Substitution Reaction Of Pseudohalogen Ion And Ion Pair At Carbon

In this paper, we have systematically investigated the anionic and ion-pair nucleophilic substitution reactions of pseudohalogen anions and molecules, NCO? (cyanate anion), NCS? (thiocyanate anion), LiNCO (lithium isocyanate) and LiNCS (lithium isothiocyanate) with CH3X(X = F, Cl, Br and I) by using HF(Hartree-Fock) and MP2 (the second-order Moller-Plesset theory) methods with 6-311+G(d,p) basis set for Li, O, S, N, C, H and X = F, Cl elements and with Wadt and Hay effective core potentials for the bromine- and iodine- containing species. Through ab initio calculations, the characters of the energies, structures and frequency for intermediates, transition states, reactants and products can been gained. Meanwhile, we have also researched the mechanisms of various reactions in detail and obtained the following results:There are two possible reaction pathways via the different TS structures for the reactions NCO? + CH3X (X = F, Cl, Br and I). Calculated results show a preference for nitrogen in the cyanate anion as the attacking site and...