Synthesis and Characterization of<em> </em>Triphenylphosphine Adducts of Ferrocene-Based Palladacycles and Their Performance in the Suzuki and Sonogashira Reactions with Bromo- and Chloroarenes

Abstract

A new triphenylphosphine adduct of cyclopalladated ferrocenylpyridazine containing a chloride anion, <strong>2</strong><strong>a</strong>, has been synthesized from the reaction of the chloride-bridged palladacyclic dimer <strong>1</strong><strong>a</strong> with triphenylphosphine. The corresponding adducts <strong>3a</strong>,<strong>b</strong> containing<strong> </strong>iodide anion have been readily prepared through anion exchange reactions of <strong>2a</strong>,<strong>b</strong> with NaI in acetone. These complexes<strong> </strong>were characterized by elemental analysis, IR and ¹H-NMR. Additionally, their crystal structures have been determined by X-ray diffraction and intermolecular C–H···X (Cl, Br, I) bonds were found in the crystals. The use of these palladacycles as catalysts for the Suzuki and Sonogashira reactions was examined. The complexes <strong>2a</strong>,<strong>b</strong> exhibited higher catalytic activity than the corresponding <strong>3a</strong>,<strong>b</strong> in the Suzuki reaction. However, the order of activity of adducts<strong> </strong>with varying<strong> </strong>halogen anions is <strong>3a</strong>~<strong>3b</strong> > <strong>2a</strong>~<strong>2b</strong> in the Sonogashira reaction.

Keywords

• adduct
• palladacycle
• crystal structure
• Suzuki reaction
• Sonogashira reaction