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

Crystal structures of pyrazolo[1,5-a]pyrimidine derivatives solved from powder diffraction data
Chernyshev VV, Yatsenko AV, Tafeenko VA, Zhukov SG, Aslanov LA, Sonneveld EJ, Makarov VA, Granik VG, Trounov VA, Kurbakov AI
ZEITSCHRIFT FUR KRISTALLOGRAPHIE 213 (9): 477-482 1998

Abstract:
The molecular crystal structures of 3-amino-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)degrees) and 3-amino-4-nitro-6,8-dimethylpyrazolo[1,5-a]pyrimidine (C8H9N5O2; space group P (1) over bar; Z = 2; a = 7.643(2) Angstrom, b = 9.142(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 directed along the diagonals of the bc plane, while the latter crystal structure adopts dimeric arrangement.