Structures of Small Platinum Cluster Anions Pt n - : Experiment and Theory.

The structures of platinum cluster anions P t 6 - - P t 13 - have been investigated by trapped ion electron diffraction. Structures were assigned by comparing experimental and simulated scattering functions using candidate structures obtained by density functional theory computations, including spin-orbit coupling. We find a structural evolution from planar structures ( P t 6 - , P t 7 - ) and amorphous-like structures ( P t 7 - - P t 9 - ) to structures based on distorted tetrahedra ( P t 9 - - P t 11 - ). Finally, P t 12 - and P t 13 - are based on hcp fragments. While the structural parameters are well described by density functional theory computations for all clusters studied, the predicted lowest energy structure is found in the experiment only for P t 6 - . For larger clusters, higher energy isomers are necessary to obtain a fit to the scattering data.