The crystal structure of imidazole at –150°C

Abstract

The study of the crystal structure of imidazole was started in the Instituto de Fisica Alonso de Santa Cruz (Garcia Blanco & Martinez-Carrera, 1958). A tentative projection of the structure was given, but the X-ray data, taken at room temperature, were insufficient for refinement. Low-temperature data were collected and the structure solved in 1958/59 in this laboratory, while the author held a Netherlands-Spain exchange fellowship. The structure was further refined in 1963 in the Laboratory of Crystallography of the University of Pittsburgh by courtesy of Prof. G.A.Jeffrey. In the meantime Will (1963), apparently unaware of our former work, published a rough trial structure of imidazole at room temperature. Since our experimental low-temperature data are far more complete, they permit an accurate determination of the molecular geometry and of the packing in the crystal.