6-Chlorothieno[2,3-e]-1,4,2-dithiazine-3(2H)-thione-1,1-dioxide, Ammonium Salt Sesquihydrate: Synthesis, Crystal Structure and Density Functional Calculations

The title compound crystallizes in the monoclinic space group C 2 /c space group, with unit cell dimensions of a = 15.6684(3) Å, b = 7.3974(2) Å, c = 21.2669(5) Å; β = 106.7770(10)° (Z = 8). In the title compound, NH 4 + ·C 5 HClNO 2 S 4 – ·1.5 H 2 O, the 1,4,2-dithiazine ring adopts a distorted half-chair conformation. The structure displays several cooperative intermolecular N/O–H···N/O/S hydrogen-bonding interactions, giving rise to a two-dimensional layers packing motif. The layers are built up from seven component entities formed via extensive intermolecular N/O–H···N/O/S hydrogen bonds involving 6-chlorothieno[2,3- e ]-1,4,2-dithiazine-3(2 H )-thione-1,1-dioxide anions, ammonium cations and water molecules. The geometry of the title compound was fully optimized using a Density functional B3LYP/6-31G(d) and B3LYP/6-31+G(d) methods and the results were consistent with experimental values. The binding energy and associated basis set superposition as well as the thermodynamic quantities were calculated. Graphical Abstract The title compound was isolated by the addition of NH 4 Cl to 6-chlorothieno[2,3- e ]-1,4,2-dithiazine-3-thiol-1,1-dioxide sodium salt. The X-ray structure and optimized geometry by DFT calculations are comparable. The structure displays several cooperative N/O–H···N/O/S hydrogen-bonding interactions, giving rise to a two-dimensional layers packing motif.