Theoretical study of the insertion reactions of Zr+ into HF, HCl, H2O, H2S, NH3, PH3, CH4, and SiH4

The insertion reactions of transition metal cation doublet Zr+(D-2) into HF, HCl, H2O, H2S, NH3, PH3, CH4, and SiH4 have been studied by means of ab initio molecular orbital calculations incorporating electron correlation with the Moller-Plesset perturbation theory up to the second and the fourth orders and the hybrid density functional method, B3LYP. Three regions of the potential surface have been investigated, an ion-molecule complex, followed by a three-center, four-electron transition state, and then an insertion product. It is found that all insertion reactions are exothermic and all transition states are below the energy surfaces of the reactants. For the ion-molecule complexes, the binding energies of the same-row hydrides increase from right to left, with the exception of CH4 and SiH4, Whose binding energies decline considerably; while to the same-group hydrides the ion-molecule complexes in the up row are more bound than those in the down row. The stability of the insertion product H-Zr+-RHn-1 decreases from right to left across the row and falls from up to down across the column. The reaction barrier follows the same trend; i.e., the more exothermic the insertion reaction is, the lower is the reaction barrier. All these observed trends could be understood by a combined effect of the electrostatic interaction and the covalent interaction.