In general, Pt7Ge2 has one centrally located Ge atom that coordinates with 3 or 4 Pt atoms, with a second Ge atom near the cluster periphery, coordinated with 3 Pt atoms. No accessible isomers with direct Ge-Ge bonds were found. For Pt7Ge2C2, the isomers are very similar to those of Pt7 and Pt7Ge2, in which all the Pt are exposed, and the added C atoms sit on the edge of the clusters. The structures of Pt7Ge2C2 are quasi-planar with features similar to the isomers of Pt4GeC2, i.e., the Ge atoms are bound in sites near the cluster periphery, coordinated to 2 to 4 Pt atoms, while the C atoms are more centrally located, each bonded to three Pt atoms. In contrast to Pt4GeC2, Pt7Ge2C2 does not have direct C-C bonds for the accessible isomers. None of the Pt7Ge2C2 (or Pt4GeC2) isomers have direct Ge-C bonding, and in all cases, the carbon atoms are in the plane of the cluster, rather than on top of Pt atoms. The latter point is consistent with the ISS experiments (Fig. ), which showed that carbon tends to bind in sites where it does not strongly attenuate He + scattering from Pt.