title: Two tautomeric polymorphs of 2,6-dichloropurine.
abstract: Two polymorphs of 2,6-dichloropurine, C(5)H(2)Cl(2)N(4), have been crystallized and identified as the 9H- and 7H-tautomers. Despite differences in the space group and number of symmetry-independent molecules, they exhibit similar hydrogen-bonding motifs. Both crystal structures are stabilized by intermolecular N-H···N interactions that link adjacent molecules into linear chains, and by some nonbonding contacts of the C-Cl···π type and by π-π stacking interactions, giving rise to a crossed two-dimensional herringbone packing motif. The main structural difference between the two polymorphs is the different role of the molecules in the π-π stacking interactions.
authors.affiliation: Departamento de Química Farmacéutica y Orgánica, Facultad de Farmacia, Universidad de Granada, Campus de Cartuja s/n, 18071 Granada, Spain.
authors.forename: M Eugenia
authors.initials: ME
authors.lastname: García-Rubiño
authors.forename: Duane
authors.initials: D
authors.lastname: Choquesillo-Lazarte
authors.forename: M C
authors.initials: MC
authors.lastname: Núñez
authors.forename: Joaquín M
authors.initials: JM
authors.lastname: Campos
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D015394:Molecular Structure; D011687:Purines / Q000737:chemistry*
chemical_list: D011687:Purines; C031268:2,6-dichloropurine