STRUCTURES OF N-AMINOGUANINE HYDROCHLORIDE SALTS

1-Aminoguanine hydrochloride (1), C5H7N6O+.Cl-, M(r) = 202.6, monoclinic, P2(1)/a, a = 17.927 (2), b = 9.219 (1), c = 4.737 (1) angstrom, beta = 93.28 (1)-degrees, V = 781.5 (2) angstrom 3, Z = 4, D(x) = 1.722 Mg m-3, lambda(Cu K-alpha) = 1.5418 angstrom, mu = 4.17 mm-1, F(000) = 416, T = 280 K, R = 0.062 for 1027 reflections. 7-Aminoguanine hydrochloride monohydrate (2), C5H7N6O+.Cl-.H2O, M(r) = 220.6, monoclinic, P2(1)/a, a = 14.665 (5), b = 12.907 (7), c = 4.642 (5) angstrom, beta = 91.38 (5)-degrees, V = 878.3 (11) angstrom 3, Z = 4, D(x) = 1.668 Mg m-3, lambda(Cu K-alpha) = 1.5418 angstrom, mu = 3.84 mm-1, F(000) = 456, T = 280 K, R = 0.068 for 897 reflections. 9-Aminoguanine hydrochloride (3), C5H7N6O+.Cl-, M(r) = 202.6, monoclinic, P2(1)/n, a = 4.778(1), b = 14.142 (2), c = 11.736 (2) angstrom, beta = 97.77 (1)-degrees, V = 785.9 (2) angstrom 3, Z = 4, D(x) = 1.713 Mg m-3, lambda(Cu K-alpha) = 1.5418 angstrom, mu = 4.15 mm-1, F(000) = 416, T = 280 K, R = 0.061 for 971 reflections. The three N-aminoguanine molecules take a cationic form with the protonation at the ring-N atom in the imidazole moiety. For the most part, the corresponding bond lengths and angles of (1), (2) and (3) are in agreement with each other. Extensive hydrogen-bond networks are formed in all three crystals.