Tautomerism and hydrogen bonding in guaninium phosphite and guaninium phosphate salts

Abstract

The crystal structures of three similar guaninium salts, guaninium monohydrogenphosphite monohydrate, C5H6N5O+·H2O3P−·H2O, guaninium monohydrogenphosphite dihydrate, C5H6N5O+·H2O3P−·2H2O, and guaninium dihydrogenmonophosphate monohydrate, C5H6N5O+·H2O4P−·H2O, are described and compared. The crystal structures have been determined from accurate single-crystal X-ray data sets collected at 100 (2) K. The two phosphite salts are monoclinic, space group P21/c, with different packing and the monophosphate salt is also monoclinic, space group P21/n. An investigation of the hydrogen-bond network in these guaninium salts reveals the existence of two ketoamine tautomers, the N9H form and an N7H form.