Statistical analysis of structural data and detailed inspection of individual crystal structures culled from the Cambridge Structural Database and the Brookhaven Protein Data Bank show that covalently bound fluorine (in contrast to anionic fluoride) hardly ever acts as a hydrogen-bond acceptor. The weakness of covalently bound fluorine as hydrogen-bond acceptor is backed by results of new molecular orbital calculations on model systems using ab initio intermolecular perturbation theory (IMPT), and is in accord with results of other physicochemical studies and with the physical properties of fluorinated organic compounds. Factors influencing the strength of hydrogen bonding in extended systems are discussed.

Keywords: Ab initio calculations; Cambridge structural database; Chemistry; Fluorine compounds; Hydrogen bonds; Protein data bank.

Reprints: J D Dunitz, ETH (Federal Technical Institute) Zurich, Organic Chemistry Laboratory, Universitat Str 16, Ch-8092 Zurich, Switzerland.

FLUORIDE 30 (3)  1997, p. 191	International Society for Fluoride Research
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