Conformational pseudo-polymorphism and hydrogen bonding: benzthiazide anhydrate and monohydrate, an antihypertensive drug

Crystal structures of benzthiazide [6-chloro-3-[[(phenylmethyl)thio]ethyl]4H-1,2,4-benzthiadiazine-7-sulfonamide-1,1,dioxide] in its anhydrate and monohydrate forms reveal, respectively, a J-like folded as well as extended type conformations that have critical torsional flexibility along the C–C–S–C bonds and novel H-bonded sulfonamide motifs.