IR Signature of Size-Selective CO2 Activation on Small Platinum Cluster Anions, Pt-n(-) (n=4-7)

Infrared multiple photon dissociation spectroscopy (IR-MPD) has been employed to determine the nature of CO2 binding to size-selected platinum cluster anions, Pt-n(-) (n=4-7). Interpreted in conjunction with density functional theory simulations, the results illustrate that the degree of CO2 activation can be controlled by the size of the metal cluster, with dissociative activation observed on all clusters n >= 5. Of potential practical significance, in terms of the use of CO2 as a useful C1 feedstock, CO2 is observed molecularly-bound, but highly activated, on the Pt-4(-) cluster. It is trapped behind a barrier on the reactive potential energy surface which prevents dissociation.