Polymorphism of malononitrile. Crystallographic characterization of the L-F phase transition

The L-F phase transition of malononitrile, CH₂(CN)₂, has been characterized by powder X-ray diffraction analysis. The powder data of L and F phases are given. Crystallographic results are consistent with spectroscopic and calorimetric ones which indicate that this transition is of first order and corresponds to a reconstructive mechanism.