STRUCTURE OF 8-AMINO-3,4-DIHYDRO-2H,6H-PYRIMIDO[2,1-B][1,3]THIAZIN-6-ONE

C7H9N3OS, M(r) = 183.23, monoclinic, P2(1)/c, a = 7.152 (2), b = 15.407 (3), c = 7.493 (2) angstrom, beta = 101.36 (3)-degrees, V = 809.5 (9) angstrom 3, Z = 4, D(x) = 1.50 g cm-3, lambda(Mo K-alpha) = 0.7107 angstrom, mu = 3.0 cm-1, F(000) = 384, T = 293 K, R = 0.040 for 1500 unique reflections with I greater-than-or-equal-to 3-sigma(I). The structure consists of statistically disordered molecules with occupancy factors of 0.815 and 0.185. The disorder arises from two alternative half-chair conformations of the thiazine ring. The crystal packing is determined by intermolecular hydrogen-bonding interactions.