HETEROCYCLES

■ Organopalladium (II) Complexes Containing Carbon-bonded Pyridine and Picoline as a Ligand: Preparation, Structures, and Reactions

Kiyoshi Isobe and Shinichi Kawaguchi*

*Department of Chemistry, Faculty of Science, Osaka University, Toyonaka, Osaka 560-8531, Japan

Abstract

Oxidative addition reactions of monohalopyridines, 2,6-dichloropyridine, 2-chloropyrazine, and 2-chlorobenzothiazole as well as 2- and 3-chloromethylpyridines with tetrakis(triphenylphosphine)palladium(0) gave [PdX(R) (PPh₃)]₂ or [PdX(R) (PPh₃)₂] depending on the nature of the carbon-bonded heterocycles R. Most of these novel organopalladium(II) complexes were characterized by the analytical, molecular-weight, and IR data together with the ¹H and ¹³C NMR spectroscopy. The molecular structures of some pyridyl and picolyl complexes were determined by X-ray analysis to reveal the novel C,N-bridging modes of the 2-pyridyl and 2-picolyl ligands. Reactions of these complexes with carbon monoxide and other reagents were examined. The pyridyl complexes catalyze the cross coupling reactions between halopyridines and methylmagnesium bromide.