Abstract
The title mol-ecule, C(18)H(16)N(2)OS, exhibits a slight 'ruffling' of the imidazolone ring, and the lone pair on the tricoordinate nitro-gen atom is involved in N→C π-bonding within the ring. Both the methyl group bonded to sulfur and the vinyl substituent lie very close to the plane of the five-membered ring. In the crystal, C-H⋯O hydrogen bonds form inversion dimers, which are linked into chains extending along the b-axis direction by C-H⋯π(ring) inter-actions. Hirshfeld surface analysis indicates that H⋯H inter-actions account for more than half of the inter-molecular contacts, with C-H⋯π(ring) inter-actions contributing a further quarter of the total.