title: Secondary interactions in the isomorphous compounds 2,6-bis(chloromethyl)pyridinium chloride and 2,6-bis(bromomethyl)pyridinium bromide.
abstract: The title compounds, C7H8Cl2N+.Cl- and C7H8Br2N+.Br-, are isomorphous. In the crystal packing, layers parallel to the ac plane are formed by a classical N(+)-H...X- hydrogen bond (X = halogen) and two X...X contacts. A third X...X contact links the layers, and a fourth, which is however very long, completes a ladder-like motif of halogen atoms. Hydrogen bonds of the form C-H...X play at best a subordinate role in the packing.
authors.affiliation: Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Postfach 3329, 38023 Braunschweig, Germany.
authors.forename: Virginia
authors.initials: V
authors.lastname: Lozano
authors.forename: Peter G
authors.initials: PG
authors.lastname: Jones