Theoretical study of the interaction between Au(I) and I on the [AuI2]−-I2 complexes

We studied the interaction between [AuI2]− and I2 using ab initio methodology. We found that the changes around the equilibrium intermolecular distance Au⋯l2 and in the interaction energy differences are sensitive to the electron correlation potential. We evaluated these effects using several levels of theory, including MP2, MP4 and CCSD(T); and size of the basis set on atoms. The equilibrium distances Au-l2 in the complexes are in the range 380-392 pm. The obtained interaction energies differences at the equilibrium distance range from 4.3 to 14.7 kJ/mol at the different levels used. These results indicate that the complexes formed are in the category of van der Waals systems. At long-distances, the behaviour of the [AuI2]−⋯I2 interaction may be related mainly to charge-induced dipole and dispersion terms. Both terms are important.