Communication: The structures of small cationic gas-phase platinum clusters

The structures of small platinum clusters Pt-3-5(+) are determined using far-infrared multiple photon dissociation spectroscopy of their argon complexes combined with density functional theory calculations. The clusters are found to have compact structures, and Pt-4(+) and Pt-5(+) already favor three-dimensional geometries, in contrast to a number of earlier predictions. Challenges in applying density functional theory to 3rd row transition metal clusters are addressed. Preliminary calculations suggest that the effects of spin-orbit coupling do not change the favoured lowest-energy isomers. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4726403]