Intermolecular and intramolecular hydrogen bonding in 5‐pyridylmethylenehydantoins: IR and NMR study

Abstract The patterns of the NH stretching vibrations in the solid‐state IR spectra of a series of 5‐pyridylmethylenehydantoins revealed the presence of various modes of hydrogen bonding: intermolecular NH&4nldr; &4nldr;OC and intermolecular or intramolecular NH&4nldr; ‥‥N(py). These variations are related to the orientation of the pyridyl nitrogen and to stereochemistry. A distinction between intramolecularly and intermolecularly hydrogen‐bonded compounds was also provided by comparison of the 1 H NMR spectra in (CD 3 ) 2 SO and in CDCl 3 .