6-(4-Fluoro-phen-yl)-8-phenyl-2,3-dihydro-4H-imidazo[5,1-b][1,3] thiazin-4-one: An unusual [6-5] fused-ring system

Abstract

The title compound, C18H13FN2OS, is the first structural example of a [6-5] fused ring incorporating the 2,3-dihydro-4H-imidazo[5,1-b][1,3]thia-zin-4-one mol-ecular scaffold. The six-membered 2,3-dihydro - 1,3-thia-zin-4-one ring adopts an envelope conformation, with the S - CH2 C atom displaced by 0.761 (2) Å from the five-atom plane (all within 0.05 Å of the mean plane). The imidazole ring is planar. The phenyl ring is twisted from coplanarity with the imidazole ring by 23.84 (5)° and the 4-fluoro-phenyl ring is twisted by 53.36 (6)°, due to a close C(aryl) - H⋯O=C contact with the thia-zin-4-one carbonyl O atom. The primary inter-molecular inter-action involves a CH2 group with the F atom [C⋯F = 3.256 (2) Å and C - H⋯F = 137°]. © International Union of Crystallography 2007.