Highly correlated ab-initio wavefunctions within the MRCI approaches are
used in a comparative study of the interactions between C2 and the three hydro-
gen halides HX (X = F, Cl, Br). Some test results are also presented within the
UCCSD(T)-F12 approach. The asymptotic regions are investigated for different
relative orientations of the two moities. It is shown that the three systems C2 +
HX are bound, for intermolecular distances close to 3 Å, through nucleophilic in-
teractions between C2 and HX for approaches perpendicular to the C-C axis, with
decreasing interaction energies from HF to HBr. For HX approaching C2 along
its axis, the interactions are governed by the electrophilic character of C2 and the
interaction energies are decreasing from HBr to HF. Activation barriers towards
the molecular systems HCCX or CCHX (0.58 eV and more) are calculated at short
distances, making difficult the reactions towards the corresponding tetra-atomic
systems.
| Type : | : | affiche |
| Mots-Clés | : | electophilic ; nucleophilic ; ab ; initio ; reactivity ; dissociation ; activation barriers. |
| PDF version | : |  PDF version |
