Theoretical study of Ar–MCO (M = Pd, Pt)

Ab initio calculations are performed for noble-gas complexes, Ar–PdCO and Ar–PtCO, by QCISD(T) with a Douglas–Kroll relativistic scheme. The electronic ground states of Ar–PdCO and Ar–PtCO are predicted to be 1Σ with linear equilibrium structure, and the binding energy of Ar is estimated as 5.3 and 8.2 kcal/mol for Ar–PdCO and Ar–PtCO, respectively. The M–C–O (M = Pd, Pt) bending frequency in MCO increases by ∼10% in Ar–MCO. The present calculations suggest that the experimentally reported M–C–O bending frequencies for MCO measured in the solid argon matrix are possibly to be assigned to the overtone band of the M–C–O bending mode of Ar–MCO.