Self-association based on orthogonal C=O...C=O interactions in the solid and liquid state.

A network of orthogonal C=O...C=O interactions was identified in the X-ray crystal structure of an alpha,alpha-difluorocyclopentanone derivative. This finding inspired investigations of self-association driven by these weak dipolar interactions in apolar solvents, which was proven by (1)H NMR spectroscopy.