LAUSR

Abstract The Pd + CO reaction has been reinvestigated using deposition of ground state reagents in solid argon and neon and the formation of Pdm-CO (m = 2–4) and Pd2-(CO)2 molecules is evidenced by many absorption in the range of 2015–1700 cm−1. These bands are also accompanied by other signals in far-infrared. In argon, selective irradiation in visible leads to conversion between two Pd2-CO isomers distinguished by the stretching frequency of the diatomic CO: bridged T-shaped (νCO = 1856 cm−1) and end on (νCO = 2015 cm−1). The experimental data, with the help of isotopic effects, are fully supported by theoretical calculations with density functional theory. The nature of chemical bonding has been also discussed within the topological approach. It has been shown that the CO complex adapts his valence basins to the geometrical symmetry of Pdm-CO when interacting with Pdm clusters.