Crystal structure of the anticancer drug carmustine determined by X-ray powder diffraction

The structure of the anticancer drug carmustine (1,3-bis(2-chloroethyl)-1-nitrosourea, C5H9Cl2N3O2) was successfully determined from laboratory X-ray powder diffraction data recorded at 278 K and at 153 K. Carmustine crystallizes in the orthorhombic space group P2(1)2(1)2(1) with Z = 4. The lattice parameters are a = 19.6935(2) angstrom, b = 9.8338(14) angstrom, c = 4.63542(6) angstrom, V = 897.71(2) angstrom(3) at 153 K, and a = 19.8522(2) angstrom, b = 9.8843(15) angstrom, c = 4.69793(6) angstrom, V = 921.85(2) angstrom(3) at 278 K. The Rietveld fits are very good, with low R-values and smooth difference curves of calculated and experimental powder data. The molecules form a one-dimensional hydrogen bond pattern. At room temperature, the investigated commercial sample of carmustine was amorphous.