When do interacting atoms form a chemical bond? Spectroscopic measurements and theoretical analyses of dideuteriophenanthrene.

Don't rewrite the textbooks! Vibrational spectra of a selectively deuterated derivative of phenanthrene indicate that the C4HHC5 interaction in its "bay" area should be interpreted as steric (Pauli) repulsion. These findings and the results of theoretical analysis are in conflict with interpretations that describe this interaction as strongly stabilizing.