Theoretical study on structures and infrared spectroscopy of Cu2+(H2O)Arn (n = 1–4)

Abstract

The binding energy of Cu²⁺(H₂O) is computed to be 98.4 kcal/mol and thus one-photon photodissociation is not possible in the 3400–3800 cm^–1 (9.7–10.9 kcal/mol) region. To study whether the infrared photodissociation processes of Cu²⁺(H₂O) can occur by multiple argon atoms tagging technique, density functional and CCSD(T) methods are used to investigate the geometries, OH stretching frequencies and the argon atom binding energies of Cu²⁺(H₂O)Ar_n (n = 1–4) complexes. Various isomers are found resulting from the different coordination sites of argon atoms. The OH stretches in these complexes are shifted to lower frequencies than those of the free water molecule, and the corresponding vibrational red shifts are progressively smaller as more argon atom is added to Cu²⁺ while binding an argon atom to an OH site should lead to additional sizable red shift to the OH stretching vibrations.