CRYSTAL-STRUCTURES OF PYRAZOLO[1,5-A]PYRIMIDINE DERIVATIVES SOLVED FROM POWDER DIFFRACTION DATA

The molecular crystal structures of no-4-nitro-6-methyl-8-oxopyrazolo[ 1,5-a]pyrimidine (C7H7N5O3; space group P2(1)/n; Z = 4; a = 18.920(4) Angstrom, b = 8.441(2) Angstrom, = 5.210(1) Angstrom, beta = 90.82(2)d egrees) and mino-4-nitro-6,8-dimethylpyrazolo[1,5-a]pyrimidine (C8H9N5 O2; space group P (1) over bar; Z = 2; a = 7.643(2) Angstrom, b = 9.14 2(3) Angstrom, c = 7.492(1) Angstrom, alpha = 111.12(2)degrees, beta = 100.66(2)degrees gamma = 102.58(2)degrees) have been determined from X-ray and neutron powder diffraction data using grid search procedure. The hydrogen-bonded molecules of the former compound form chains dire cted along the diagonals of the bc plane, while the latter crystal str ucture adopts dimeric arrangement.