Crystal structures of pyrazolo[1,5-a]pyrimidine derivatives solved from powder diffraction data

The molecular crystal structures of 3-amino-4-nitro-6-mefhyl-8-oxopyrazolo[1,5-a]pyrimidine (C7H7N5O3; space group P21/n; Z = 4; a = 18.920(4) Å, b = 8.441(2) Å, c = 5.210(1) Å, β = 90.82(2)°) and 3-amino-4-nitro-6,8-dimethylpyrazolo[1,5-a]pyrimidine (C8H9N5O2; space group P[unk]; Z = 2; a = 7.643(2) Å, b = 9.142(3) Å, c = 7.492(1) Å, α = 111.12(2)°, β = 100.66(2)°, γ = 102.58(2)°) 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 directed along the diagonals of the bc plane, while the latter crystal structure adopts dimeric arrangement.