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Inspect the diagram of this molecule (Figure, bottom row) very carefully (you will need a magnifying glass) and note the eight pairs of hydrogens in the ortho positions of the phenyl groups. Adjacent pairs of such hydrogens do seem very close. In fact, estimated from comparing with the adjacent C-C lengths of about 1.4A, the H...H contacts must be about 0.8A. There are other hints from the article that this geometry is assumed to be planar, with D4h symmetry. The vibrations are reported as calculated on the basis of this geometry, which in fact turns out to be a higher order stationary point in the potential surface of the free molecule.

I find the close H...H approaches (eight of them) surprising, given that the closest non-bonded H..H approach ever measured is about 1.5A. Calculations suggest this molecule is far from planar in its low energy state, and even just twisting the phenyl groups to be co-planar with the adjacent ring does not produce an overall planar molecule. I estimate the energy of a fully planar (but otherwise relaxed) system is about 180 kcal/mol above that of the fully relaxed molecule. An analysis of these energies and various other aspects can be found at DOI: 10.14469/hpc/5560 and DOI: 10.14469/hpc/5559

I think it worth establishing what the geometry of the molecule on Cu or Au surfaces actually is before correlating calculated vibrations with the measurements reported in this article. If the CoTPP system really is planar with ultra-short non-bonded H...H contacts, that would be a discovery indeed. I think it more reasonable that this species remains very non-planar on the metal surfaces and that the interpretation of these imaged normal modes may be more complex than suggested in this article.

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