CRYSTAL-STRUCTURES OF DRO-6-HYDROXY-7H-1,2,4-TRIAZOLO[3,2-B]1,3-THIAZINE AND DRO-6-HYDROXY-7H-1,2,4-TRIAZOLO[3,2-B]1,3-THIAZINE

The examined compounds crystallize in the monoclinic space groups P2(1 )/c (phenyl derivative, 1) and P2(1)/a (benzyl derivative, 2). The uni t cell parameters a, b, c (Angstrom) and beta (degrees) were: 6.402(1) , 16.506(1), 10.144(1), 97.48(1) for 1 and 12.099(2), 4.612(1), 21.712 (4) and 105.20(2) for 2. The final R(Rw) factors were 0.043 (0.041) an d 0.121 (0.126) for 1 and 2, respectively. Both molecules have similar geometry of the bicyclic system with flat 1,2,4-triazole rings, sofa conformations of 1,3-thiazole ones and axial hydroxy groups. In the cr ystals the molecules form infinite chains (by means of O-H...N(4) hydr ogen bonds), enantiomeric in 1 and racemic in 2.