Unusual bonding in platinum carbido clusters.

Vibrational spectroscopy and density functional theory calculations are used to determine the structures of small gas-phase platinum carbido dusters Pt_nC⁺, n = 3-5. The carbon atom is found to prefer three-coordinate binding sites near the center of the duster, in contrast to most previously investigated adatoms on transition metal clusters. The Pt₃C unit is particularly stable, and binding of the carbon atom also leads to significant rearrangement of the metal framework when compared to the bare clusters