title: Molecular pair analysis: C-H...F interactions in the crystal structure of fluorobenzene? And related matters.
abstract: The crystal structure of fluorobenzene is compared with isomorphous crystal structures of molecules of roughly similar shape. The lowest-energy fluorobenzene dimers are identified by theoretical calculations. Molecular pair analysis of the crystal structure of fluorobenzene and of an isomorphous virtual low-energy polymorph of benzene suggests that the important intermolecular interactions in the two structures are closely similar. In particular, the intermolecular C-H...F interactions in the fluorobenzene crystal have approximately the same structure-directing ability and influence on the intermolecular energy as the corresponding C-H...H interactions in benzene. Molecular pair analysis of the isomorphous crystal structures of benzonitrile, alloxan, and cyclopentene-1,2,3-trione indicates that essentially the same crystal structure can be adopted with quite different patterns of pair energies and atom-atom interactions. The question as to whether the packing radius of organic fluorine is larger or smaller than that of hydrogen, is addressed, but not answered.
authors.affiliation: Organic Chemistry Laboratory, ETH-Zurich, 8093 Zurich, Switzerland. dunitz@org.chem.ethz.ch
authors.forename: Jack D
authors.initials: JD
authors.lastname: Dunitz
authors.forename: W Bernd
authors.initials: WB
authors.lastname: Schweizer