η 3 -allyl-Pd(II) complexes of 2-, 3- and 4-pyridylmethyl- coumarin esters

A series of 2-, 3- and 4-pyridylmethyl-coumarin esters ligands (1–3) and their η3-allyl palladium complexes (1-Pd – 3-Pd) have been designed, synthetized and characterized. NMR analysis of compounds 1-Pd – 3-Pd indicated the presence of the allyl fragment. The molecular structure of 2, 3 and 1-Pd was determined by X-ray crystallographic analysis. The molecular structure 1-Pd reveals that coumarin ligand (2) is coordinated to the palladium center via a monodentate fashion through the nitrogen atom of the pyridinyl fragment while the allyl group is binding via a η3 fashion in an overall square-planar geometry completed with a chloride atom. An investigation of intermolecular interactions in crystal packing via a Hirshfeld surfaces and fingerprint plots analyses showed a wide variety of intermolecular contacts such as H•••O and H•••N hydrogen bonding, π•••π stacking, C–H•••π and carbonyl (lone pair)•••π interactions that generated polymeric arrays.