Syntheses and characterization of 5-substituted hydantoins and thiazolines- implications for crystal engineering of hydrogen bonded assemblies. Crystal structures of 5-(2-pyridylmethylene)hydantoin, 5-(2-pyridylmethylene)-2-thiohydantoin, 5-(2-pyridylmethylene)thiazolidine-2,4-dione, 5-(2-pyridylmethylene)rhodanine and 5-(2-pyridylmethylene)pseudothiohydantoin

A series of six potentially bidentate ligands composed of 5-membered hetero cyclic rings with methylenepyridyl substituents are described. These molecu les are potentially bifunctional, acting as bidentate ligands to metal cent res whilst retaining on their periphery a range of groups capable of formin g triple hydrogen bonds. Their metal complexes have the potential to displa y interesting magnetic, optical and electrochemical properties when the hyd rogen bonds are used for the crystal engineering of solid state materials. Here we report the synthesis and characterization of the six closely relate d molecules, 5-(2-pyridylmethylene)hydantoin I, 5-(2-pyridylmethylene)-2-th iohydantoin II, 5-(2-pyridylmethylene)thiazolidine-2,4-dione III, 5-(2-pyri dylmethylene)rhodanine IV, 5-(2-pyridylmethylene)pseudothiohydantoin V and 5-(2-pyridylmethylene)-2-imino-4-amino-2,5-dihydrothiazole VI. The solid st ate structures of I-VI have been studied using natural abundance solid stat e N-15 NMR spectroscopy and the single crystal structures of I-V are discus sed.