This Letter presents an ab initio investigation on several dimeric complexes of fluorine-containing molecules with ammonia. Fluorine bond energies, computed at the MP2/aug-cc-pVTZ level of theory, vary in a range from - 0.13 to - 9.30 kcal/mol, thus indicating that fluorine bonding interactions are comparable in strength to traditional halogen bonds. The quantum theory of atoms in molecules and the second-order perturbation natural bond orbital analyses are also applied to explore the nature of fluorine bonding. (c) 2007 Elsevier B.V. All rights reserved.