title: Crystal structure of disodium 2-amino-6-oxo-6,7-di-hydro-1H-purine-1,7-diide hepta-hydrate.
abstract: In the title compound, disodium 2-amino-6-oxo-6,7-di-hydro-1H-purine-1,7-diide hepta-hydrate, 2Na(+)·C5H3N5O(2-)·7H2O, the structure is composed of alternating (100) layers of guanine mol-ecules and hydrated Na(+) ions. Within the guanine layer, the mol-ecules are arranged in centrosymmetric pairs, with a partial overlap between the guanine rings. In this compound, guanine exists as the amino-keto tautomer from which deprotonation from N1 and N7 has occurred (purine numbering). There are no direct inter-actions between the Na(+) cations and the guanine anions. Guanine mol-ecules are linked to neighboring water mol-ecules by O-H⋯N and O-H⋯O hydrogen bonds into a network structure.
authors.affiliation: Department of Structural Biology, Weizmann Institute of Science, 76100 Rehovot, Israel.
authors.forename: Dvir
authors.initials: D
authors.lastname: Gur
authors.affiliation: Chemical Research Support, Weizmann Institute of Science, 76100 Rehovot, Israel.
authors.forename: Linda J W
authors.initials: LJ
authors.lastname: Shimon
keywords: crystal structure; guanine salt; hydrogen bonds; nucleobase
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