Fluorine is much more electronegative (3.98) than Nitrogen (3.04) and Oxygen (3.44). As such, its bonding to Hydrogen is much stronger than that of N and O.

Article The Strength of Hydrogen Bonds Between Fluoro-Organics and A...

Dear Rajiv Lakkaniga please check out the following review articles. According to these references, fluorine has only a weak (poor) hydrogen‐bond‐acceptor strength because the fluorine atom itself is non-polarizable.

Article Organic Fluorine: Odd Man Out

Article Organic Fluorine as a Hydrogen-Bond Acceptor: Recent Example...

According to this paper, organic fluorine is polarizable:

Article Revealing the Polarizability of Organic Fluorine in the Trif...

Dear Martin Klvana, interesting contribution! Apparently this continues to be a a controversial issue.

Frank T. Edelmann, indeed; i once witnessed a debate (without a clear resolution) as to whether C-F...H interaction is a hydrogen bond or not -- perhaps it was a case of logomachy? The debate involved the authors of the paper below; the paper shows the effect of X (H or F) in X-C-F on the capacity of F to interact with the guanidinium group of an arginine residue in the active site of DNA polymerase β:

Article (R)-β,γ-fluoromethylene-dGTP-DNA ternary complex with DNA polymerase β

Martin Klvana and Frank T. Edelmann

I personally believe this problem can be explained based on an electronegativity argument, as I mentioned in my previous answer. F is the most electronegative element in the periodic table. As such, it can easily grab an electron from its neighbours to complete its p-shell, especially if they are low-electronegative elements such as H. In this sense, an H..F-type interaction is too strong to be considered as hydrogen bonding. It's either ionic (and thus polarizable) or at least covalent.

• Frank T. Edelmann ( - ) you are right, fluorine is low polarizible in aliphatic systems, and in some extent in aromatic molecules. As I see, opponents trying to think but have no high-level education. Attempts to refer to strong H...F(-) bond have no relevance as it is bond with IONIC F-anion - in contrary to COVALENT C-F bond.
• Publication cited in second message of Martin Klvana (

  Article Revealing the Polarizability of Organic Fluorine in the Trif...

  ) - is really example of scientific profanation. Ordering of fluorinated (perfluorinated) mojeties near the same groups cased NOT by high energy, but LOW energy, to optimize ordering of groups with high energy of intermolecular interaction.

Andrei Rogoza, as weak as the C-F...H interaction may be (relative to some other, stronger interactions), it may be strong enough to exert meaningful biological effects; therefore, the importance of such interaction ought not to be dismissed without careful consideration of the specific case in question.

Andrei Rogoza your "high-level education" seems to lack some fundamental elements!

Dear Martin Klvana , I recommended your first answer, as the correct methodology was used in the cited article and the results were correctly interpreted. Unfortunately, the second citation seems to be problematic. The article was published by the American Chemical Society, and its authority affects the brain. I carefully studied the article, and I can say that neither the methodology nor the conclusions in this article inspire confidence. There are two main reasons - 1) study in the crystalline state and 2) incorrectly selected model substances. In the model substance A, in the ortho position to CF3 there is an NH donor group, which causes polarization. Everyone knows this and it is written in any publication on fluorine chemistry. In the framework of the theory of hyperconjugation, this has been explained for a very long time.

With model substance B, they try to operate with the concepts of "short contact", as well as ideas about functional groups. Unfortunately, in solid matter, these concepts have low value in explaining of polarization. It is forgotten that the molecule has a molecular orbital that interacts entirely with the molecular environment, and the deformation of the electron shells in the crystal can reach 10-15% of the "atom size". An easy and long-time known way to prove the hydrogen bond is to study the infrared spectra in solution. Moreover, replacing hydrogen atoms with deuterium is a reliable tool for identifying the position of such a bond (hydrogen atoms are not visible in a conventional X-ray diffraction). When the solution is diluted, the intermolecular bonds break up, which is immediately visible on the infrared spectrum. Unfortunately, the authors of the "stunning" discovery of a new hydrogen bond have not studied anything like this.