The Crystal Structure of Purine

The crystal structure of Purine, C5N4H4, has been determined and refined by Fourier and least-squares analyses of complete three-dimensional diffraction data from Copper X-radiation. The crystals are Orthorhombic with space group Pna21. The unit cell dimensions are a = 15.551, b = 9.3751, and c = 3.6626 Å. Least-squares refinement of the positional parameters of all 13 atoms and of the individual anisotropic temperature factors of the nine heavy atoms, using the 570 observed reflections of non-zero weight, yielded a final R factor of 0.070. The molecule containing two fused rings is planar. There is a Hydrogen on N(7) and none on N(9). N(7) participate in a Hydrogen bond of length 2.85 Å with N(9).