Nucleophilic or Electrophilic Interactions of C2 with HX systems (X=F, Cl, Br)

D. Khiri (1) , H. Gritli (1) , Gilberte Chambaud (2)

1 LSAMA - Laboratoire de Spectroscopie Atomique, Moléculaire et Applications
2 MSME - Laboratoire de Modélisation et Simulation Multi Echelle

Highly correlated ab-initio wavefunctions within the MRCI approach are used in a comparative study of the interactions between C2 and the three hydrogen halides HX (X = F, Cl, Br). Test calculations are also presented using the UCCSD(T)-F12 approach. The asymptotic regions are investigated for different relative orientations of the two moieties. It is shown that the three systems C2 + HX are bound, for intermolecular distances close to 3 Ang, through nucleophilic interactions 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, governed by the electrophilic character of C2 are decreasing from HBr to HF. Even though the reactions towards the molecular systems HCCX or CCHX are exothermic, activation barriers (0.58 eV and more) are calculated at short distances, preventing the direct reactions towards the corresponding tetra-atomic systems

Mots clés: Potential curves; long range interactions; ab-initio calculations; hydrogen halides

Domaines: Chimie théorique et/ou physique

D. Khiri, H. Gritli, Gilberte Chambaud. Nucleophilic or Electrophilic Interactions of C2 with HX systems (X=F, Cl, Br). Journal of Physical Chemistry A, 2014, 118 (32), pp.6248. ⟨10.1021/jp503651u⟩. ⟨hal-01064801⟩