Comparison of distributions of hydrogen bond lengths, calculated separately for fluorinated (LF), otherwise halogenated (LX), and non-halogenated ligands (LH), for the four most represented topologies of protein-ligand hydrogen bonds.

Those for which hydrogen bonds to LX/LF ligands are, according to the Mann-Whitney U test, significantly shorter (assuming α = 0.05) are highlighted. Note that for each pair of H-bond distributions, a smaller mean rank indicates statistically shorter donor-acceptor distances, or, equivalently, positive values of ZU statistics indicate these types of H-bonds, which are shorter to halogenated ligands. The corresponding medians, and their differences with statistical significances (p), are also presented.