Title of article :
Two new polytypes of 2,4,6-tribromobenzonitrile
Author/Authors :
Britton, Doyle Department of Chemistry - University of Minnesota, USA , Noland, Wayland E. Department of Chemistry - University of Minnesota, USA , Tritch, Kenneth J. Department of Chemistry - University of Minnesota, USA
Abstract :
Three polymorphs of 2,4,6-tribromobenzonitrile (RCN), C7H2Br3N, two of
which are novel and one of which is a redetermination of the original structure
first determined by Carter & Britton [(1972). Acta Cryst. B28, 945–950] are
found to be polytypic. Each has a layer structure which differs only in the
stacking of the layers. Each layer is composed of molecules associated through
C NBr contacts which form R2
2(10) rings. Two such rings are associated with
each N atom; one with each ortho-Br atom. No new polytypes of 1,3,5-tribromo2-isocyanobenzene (RNC) were found but a re-determination of the original
structure by Carter et al. [(1977). Cryst. Struct. Commun. 6, 543–548] is
presented. RNC was found to be isostructural with one of the novel polytypes of
RCN. Unit cells were determined for 23 RCN samples and 11 RNC samples.
Polytypes could not be distinguished based on crystal habits. In all four
structures, each molecule of the asymmetric unit lies across a mirror plane.
Keywords :
CBr contacts , NBr contacts , isocyanide , Sandmeyer , polymorphs , polytypes , crystal structure
Journal title :
Acta Crystallographica Section E: Crystallographic Communications
