Structure of 5-methoxy-2-([4-methoxy-3,5-dimethyl-2-pyridinyl) methyl]sulfinyl)-1H-benzimidazole (omeprazole).

C17H19N3O3S, Mr = 345.42, triclinic, P1, a = 10.686 (5), b = 10.608 (7), c = 9.666 (6) A, alpha = 119.75 (5), beta = 112.02 (5), gamma = 68.33 (4) degrees, V = 859 (1) A3, Z = 2, Dm = 1.332 (2), Dx = 1.335 g cm-3, Cu K alpha, lambda = 1.5418 A, mu = 18.04 cm-1, F(000) = 364, T = 293 K, R = 0.057 for 1962 observed reflections. The methylsulfinyl group, which adopts a trans conformation, links the pyridine and benzimidazole rings in an almost coplanar orientation. Thus the molecule, as a whole, adopts a nearly extended form. Two centrosymmetrically related molecules form a cyclic dimer by intermolecular N-H...O hydrogen bonding, and the dimers are held together by van der Waals contacts between the neighboring aromatic rings in the crystal structure.