Short strong hydrogen bonds in 2-acetyl-1,8-dihydroxy-3,6-dimethylnaphthalene: An outlier to current hydrogen bonding theory?

The environmental influence on the electronic character of two O-H center dot center dot center dot O hydrogen bonds in a beta-diketone, 2-acetyl-1,8-dihydroxy-3,6-dimethylnaphthalene, is studied by low-temperature synchrotron X-ray diffraction and high-level density functional theory (DFT) calculations. It is revealed that one of the hydrogen bonds is very strong, yet partial localization is found. This result is analyzed by atoms in molecules (AIM) theory and applying the source function. Model compounds, with less steric strain, reveal that the strong hydrogen bond is not merely a result of steric compression.