Syntheses, Structures, and Luminescent Properties of [Bis(iminoalkyl)pyridine]cadmium( II ) Complexes

Four new Cd II complexes of 2,6‐bis[1‐(phenylimino)ethyl]pyridine ( L 1 ), 2,6‐bis[1‐(2,6‐diisopropylphenylimino)ethyl]pyridine ( L 2 ), 2,6‐bis[1‐(2,6‐dimethylphenylimino)ethyl]pyridine ( L 3 ), 2,6‐bis[1‐(2‐methylphenylimino)ethyl]pyridine ( L 4 ) have been synthesized. These complexes have the formulas [Cd( L 1 )Cl 2 ]·1.5CH 3 CN ( 1 ), [Cd( L 2 )Cl 2 ] ( 2 ), [Cd( L 3 )Cl 2 ]·CH 3 CN ( 3 ), and [Cd( L 4 )Cl 2 ]·CH 3 CN ( 4 ). The molecular structures of complexes 1 − 4 were determined by single‐crystal X‐ray diffraction. Crystallographic studies of 1 − 4 reveal all four complexes to be five‐coordinate with geometries that can be best described as distorted trigonal‐bipyramidal. All eight compounds ( L 1 − L 4 and 1 − 4 ) are luminescent at room temperature in solution and the solid state. At 298 K in dichloromethane solution, all compounds have fluorescent emissions at about 368−409 nm. The fluorescent emission of these compounds originates from ligand‐centered π*−π transitions. The Cd II centers play a key role in enhancing the fluorescent emission of the ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)