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Geometries and bond energies of the He-MX, Ne-MX, and Ar-MX (M = Cu, Ag, Au; X = F, Cl) complexes.

Research paper by Corey J CJ Evans, Timothy G TG Wright, Adrian M AM Gardner

Indexed on: 26 Feb '10Published on: 26 Feb '10Published in: Journal of Physical Chemistry A



Abstract

Calculations on the He...MX, Ne...MX, and Ar...MX (M = Cu, Ag, Au; X = F, Cl) complexes at the CCSD and CCSD(T) levels of theory have been carried out. The geometries of the Ar-MF complexes are in good agreement to those determined via microwave spectroscopy. The RG...MX (RG = He, Ne, and Ar) dissociation energies for these complexes have been evaluated by extrapolation to the complete basis set limit. The importance of the inclusion of diffuse functions to the determined dissociation energies of these complexes are discussed with comparison to recent work. For the He...CuF and He...AuF complexes, the dissociation energies have been found to be significant, at approximately 26 kJ mol(-1), while the bonding in the chlorine analogues is only approximately 15 kJ mol(-1). The bonding between the helium and the metal atoms in the He...CuF and He...AuF complexes has been investigated by using an atoms-in-molecules (AIM) analysis together with an evaluation of the dipole/induced-dipole and ion/induced-dipole interactions. This analysis has shown that the bonding in these complexes is slightly covalent in nature. For the He...AgF and Ne...MF (M = Cu, Ag, Au) complexes the dissociation energy is much smaller and the AIM analysis shows the bonding is more electrostatic in nature. Calculations have also been carried out on He...AgCl and Ne...MCl (M = Cu, Ag, Au) complexes for the first time in addition to the Ar...MX (M = Cu, Ag, Au; X = F, Cl) complexes. The RG...MCl complexes are found to be more weakly bound than the corresponding RG...MF complexes as a result of the difference in electronegativity of the halogen. For each complex, bond lengths, rotational constants, and harmonic vibrational frequencies have also been evaluated.