A new monoclinic polymorph of 3-diethyl­amino-4-(4-meth­oxy­phen­yl)-1,1-dioxo-4H-1λ(6),2-thia­zete-4-carbonitrile

A new monoclinic form of the title compound, C(14)H(17)N(3)O(3)S, has been found upon slow crystallization from water. Another monoclinic form of the compound was obtained previously from a mixture of dichloro­methane and diethyl ether [Clerici et al. (2002 ▶). Tetra­hedron, 58, 5173–5178]. Both phases crystallize in space group P2(1)/n with one mol­ecule in the asymmetric unit. The formally single exocyclic C—N bond that connects the –NEt(2) unit with the thia­zete ring is considerably shorter than the adjacent, formally double, endocyclic C=N bond. This is likely to be due to the extended conjugated system between the electron-donor diethyl­ammine fragment and the electron-withdrawing sulfonyl group. In the newly discovered polymorph, the meth­oxy group is rotated by almost 180° around the phen­yl–OCH(3) bond, resulting in a different mol­ecular conformation.