Synthesis and characterization of novel pyridine–isourea complexes of Pd(II)

New neutral palladium(II) complexes having formula PdCl2(pyiuPr), PdCl2(pyiuCy), Pd(OCOCH3)2(pyiuPr), Pd(OCOCH3)2(pyiuCy), Pd(CH3)Cl(pyiuPr) and Pd(CH3)2(pyiuPr), where pyiuPr and pyiuCy are the novel ligands 1,3-diisopropyl-2-((pyridin-2-yl)methyl)isourea and 1,3-dicyclohexyl-2-((pyridin-2-yl)methyl)isourea, were synthesized and characterized. These neutral ligands act as bidentate and coordinate the palladium center through the pyridine N-atom and one of the nitrogen atoms of the isourea dent, as deducted by variable-temperature NMR experiments and DFT calculations and observed by X-ray diffraction experiments on the complex PdCl2(pyiuCy).

Graphical abstractPyridine–isourea ligands having formula 1,3-dialkyl-2-((pyridin-2-yl)methyl)isourea have been prepared, together with the methanesulfonate salts of their conjugate acids. These ligands act as bidentate in Pd(II) complexes and coordinate the metal center through the pyridine N-atom and one of the nitrogen atoms of the isourea dent, forming a seven-membered ring.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Polydentate pyridine–isourea N-donor ligands have been synthesized. ► These ligands act as bidentate in palladium(II) square-planar complexes. ► X-ray structures of ligands and complexes have been obtained. ► Variable-temperature NMR experiments have been carried out.