Cover Picture: Isotopic Polymorphism in Pyridine (Angew. Chem. Int. Ed. 4/2009)



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A low-temperature polymorph is found to exist for [D5]pyridine that does not exist for [H5]pyridine. In their Communication on page 755 ff., R. Boese, S. Parsons, and co-workers report the unusual complexity of the solid-state structures of one of the simplest heteroaromatic molecules. Pyridine shows the unusual property of isotopic polymorphism, which is rare for organic or molecular compounds as isotopic substitution rarely has an effect on the stabilities of crystal structures.