title: 5-Amino-2,4,6-tribromoisophthalic acid: the MAD triangle for experimental phasing.
abstract: The title compound, C(8)H(4)Br(3)NO(4), shows an extensive hydrogen-bond network. In the crystal structure, molecules are linked into chains by COO-H...O bonds, and pairs of chains are connected by additional COO-H...O bonds. This chain bundle shows stacking interactions and weak N-H...O hydrogen bonds with adjacent chain bundles. The three Br atoms present in the molecule form an equilateral triangle. This can be easily identified in the heavy-atom substructure when this compound is used as a heavy-atom derivative for experimental phasing of macromolecules. The title compound crystallizes as a nonmerohedral twin.
authors.affiliation: Department of Structural Chemistry, Georg-August-Universität Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany. tbeck@shelx.uni-ac.gwdg.de
authors.forename: Tobias
authors.initials: T
authors.lastname: Beck
authors.forename: Regine
authors.initials: R
authors.lastname: Herbst-Irmer
authors.forename: George M
authors.initials: GM
authors.lastname: Sheldrick
mesh_terms: D001966:Bromine / Q000737:chemistry; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D015394:Molecular Structure; D010795:Phthalic Acids / Q000737:chemistry*
chemical_list: C542184:5-amino-2,4,6-tribromoisophthalic acid; D010795:Phthalic Acids; D001966:Bromine