Synthesis and crystal structures of 5-amino-1-(2-hydroxyethyl)imidazole-4-carboxamide and 5-amino-1-(2-chloroethyl)-4-cyanoimidazole

Both 5-amino-1-(2-hydroxyethyl)imidazole-4-carboxamide (AHIC) and 5-amino-1-(2-chloroethyl)-4-cyanoimidazole (ACCI) have been synthesized and crystallized in the monoclinic space group P2₁/c, Z = 4, with a = 8.420(2), b = 9.759(2), c = 10.583(2) Å, = 111.80(2)° for AHIC and a = 6.139(1), b = 8.522(2), c = 15.156(3) Å, = 96.71(2)° for ACCI. Differences in the molecular geometries of the two compounds are attributed to the differences in the substituents at the 1- and 4-positions of the imidazole ring. The molecular conformation of AHIC is stabilized by intramolecular hydrogen bonding between the 5-amino and the vicinal carboxamide moiety, resulting in an extended planar structural pattern. The presence of the cyano group in the 4-position of ACCI prevents the formation of such an intramolecular hydrogen bond. Both the crystal structures are stabilized by networks of intermolecular hydrogen bonds.