CRYSTAL STRUCTURE OF [2-(P-(METHOXYPHENYL) HYDROXY) METHYLENE-2H-1,4-BENZOTHIAZINE-3-(4H)-ONE](+). K.A. Nirmala and P. Kumaradhas, Department of Physics, Bangalore University, Bangalore-560 056, INDIA

The title compound C₁₆H₁₅NO₂S.H₂O is a derivative of benzothiazine posses pharmacological activity. The exact structure was determined because of the ambiguity in chemical and physical methods. A single crystal X-ray analysis has been carried out to know about the exact conformation of molecular geometry and crystal packing. The title compound crystalyizeses with water molecule.

Crystal Data: Space group P2₁/c, Monoclinic, a=12.050(6)Å, b=5.612(2)Å, c=23.795(4)Å, (=102.46(2)Å, V=1571.2(9)ų, Z=4, (=1.5418Å, D_cal =1.350 mg/u³ and D_exp =1.345mg/u³.

The structure has been solved by direct method SHEXLS-86 and it was refined by full matrix least-squares method SHELXL-93 to the final value of R=0.049 and wR=0.11.

The 1,4-benzothiazine is significantly deviated from planarity and having distorted boat conformation. The methoxyphenyl with hydroxy group is pseudo-axial to the 1,4-benzothiazine ring. There is a strong intramolecular hydrogen bonding between the oxygen of water molecule to hydroxy group of the benzothiazine and also there is a strong interamolecular hydrogen bonding between oxygen of the water molecule to carbonyl oxygen. The molecular packing is stabilized by three dimensional hydrogen bonding network. The amide group hydrogen bond with adjacent molecules forms centrosymmetric dimers in the crystal. This is the important facit of the molecular packing.