CHARGE-TRANSFER COMPLEXES BETWEEN DIHALOGEN COMPOUNDS AND ELECTRON-DONORS

A theoretical study of the charge-transfer complexes formed by dihalog en compounds (F-2, Cl-2, Br-2, FBr, FCl, and ClBr) and electron donors (FH, OH2, NH3, CO, NCH, and C2H2) has been carried out. The geometrie s, energies, and electronic and spectroscopic properties of these comp lexes have been compared with the corresponding properties of the hydr ogen bonded complexes of FH with the same electron donors. The hybrid HF-DFT, B3LYP, and second-order Mollet-Plesset perturbation, MP2, meth ods have been used. The properties analyzed include geometry, energy, electron distribution using the atoms in molecules (AIM) methodology, and spectroscopic constants of the complexes and monomers. Similaritie s in the variations of the geometries, in the trends in the interactio n energetic, and in the topological electron density characteristics b etween the properties of the HE complexes and the dihalogen charge-tra nsfer systems are pointed out. The main differences correspond to the variation trend of the atomic properties and the NMR shielding when go ing from the monomers to the complexes.