Matrix isolation infrared spectroscopic and density functional theory studies on the reactions of yttrium and lanthanum hydrides with carbon monoxide.

Laser-ablated yttrium and lanthanum hydrides have been co-deposited at 4 K with carbon monoxide in excess argon. Products, such as HYCO, (HY)2CO, HLaCO, HLa(CO)2, and H2LaCO, have been formed in the present experiments and characterized using infrared spectroscopy on the basis of the results of the isotopic shifts, mixed isotopic splitting patterns, stepwise annealing, the change of reagent concentration and laser energy, and the comparison with theoretical predictions. Density functional theory calculations have been performed on these molecules. The agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts supports the identification of these molecules from the matrix infrared spectra. Plausible reaction mechanisms have been proposed to account for the formation of these molecules.