7-chloro-2-methyl-3-methylamino-2H-1,2,4-benzo-thiadiazine 1,1-dioxide

The title compound, C9H10ClN3O2S, was prepared for structural comparison wi th analogous products known as myorelaxants and inhibitors of insulin relea se. The 2H-tautomeric form is imposed by the presence of a methyl group in the 2-position. There are four independent molecules (A, B, C and D) in the asymmetric unit which have almost the same geometry. The C-N distances in the four thiadiazine rings [C-N single- and double-bond mean values of 1.40 5 (3) and 1.304 (3) Angstrom, respectively] may serve as reference to chara cterize the 2H-tautomeric form in analogous structures. The NH group of the methylamino substituent of each molecule participates in an intermolecular hydrogen bond with a sulfoxide O atom acting as acceptor. These four indep endent hydrogen bonds give rise to two types of infinite chains, both stret ching along the a axis and having molecular compositions of...ABABAB... and ...CDCDCD...