2-(1-Aryliminoethyl)cycloheptapyridylpalladium complexes: Synthesis, characterization and the use in the Heck-reaction

A series of 2-(1-aryliminoethyl)cycloheptapyridine derivatives (L1–L7) were prepared in good yield by the condensation reaction of 2-acetylcycloheptapyridine with various anilines, and then reacted with PdCl2(CH3CN)2 in dichloromethane to form the respective palladium(II) complexes (C1–C7). All organic and palladium compounds were characterized by FT-IR and NMR spectroscopy, as well as by elemental analysis. The molecular structures of the complexes C4, C5 and C7 were determined by single crystal X-ray diffraction studies and revealed distorted square geometries at each palladium center via the coordination of two nitrogen atoms and two chlorides. All palladium complexes exhibited good activity in the Heck cross-coupling reaction between bromoarenes and styrene, and the catalytic systems possessed high thermal stability.