Abstract
The crystal structures of four derivatives of pyrazolo[4,3-c][1,2]benzothiazine-2,4-dihydro-3,4-dimethyl-,5,5-dioxide containing benzothiazine dioxide and pyrazolo fused rings that have been synthesized were determined. (C-11 H-11 N-3 O-2 S): Mr = 249.29, monoclinic, P2(1)/c, a = 8.3070(3), b = 13.6331(5), c = 10.1661(3) angstrom, beta = 106.924(2)degrees, V = 1101.45(7) angstrom(3,) Z = 4. (C-12 H-13 N-3 O-2 S): Mr = 263.31, monoclinic, P2(1)/n, a = 9.729(3), b = 11.224(4), c = 11.436(3) angstrom, beta = 98.85(2)degrees, V = 1233.9(7) angstrom(3), Z = 4. (C-14 H-15 N-3 O-4 S): Mr = 321.35, monoclinic, P2(1)/c, a = 9.2534(3), b = 19.3920(7), c = 7.9489(2) angstrom, beta = 95.323(2)degrees, V = 1420.21(8) angstrom(3,) Z = 4. (C-14 H-15 N-3 O-3 S): Mr = 305.35, monoclinic, P2(1) /c, a = 13.816(7), b = 7.464(3), c = 14.674(8) angstrom, beta = 109.05(3)degrees, V = 1430.3(12) (3), Z = 4. The heterocyclic thiazine rings adopt half-chair conformations, and the mean-planes of the phenyl and pyrazolo rings lie between 10.43(11) and 15.93(16)A degrees with respect to each other. In each case, the geometry about thiazine N-atom is trigonal pyramidal and only the first compound containing a donor N-atom shows classical hydrogen bonds. However, non-classical H-bonding of the type C-H center dot center dot center dot O is observed in all structures.