Synthesis and characterization of double cyclopalladated complexes of Schiff bases and azine—oxidative addition of aryl-halogen bond

Abstract

The oxidative addition of aryl-halogen bonds of Schiff bases (2-ClC 6H 4CHNCH 2) 2 ( 1), (2-BrC 6H 4CHNCH 2) 2 ( 2), 1,4-(2-BrC 6H 4CHN) 2C 6H 4 ( 3), 4,4′-(2-BrC 6H 4CHNC 6H 4) 2 ( 4 and the azine (2-BrC 6H 4CHN) 2 ( 5 to Pd(dba) 2 has been carried out in benzene. Insoluble halogeno-bridged polymeric complexes [{ Pd(C 6H 4CHN CH 2)Cl} n] ( 1a), [{ Pd(C 6H 4CHN CH 2)Br} n] ( 2a), [1,4-{Br Pd(C 6H 4CHN C 6H 4 NCHC 6H 4)Pd Br} n] ( 3a), [4,4′-{ Pd(C 6H 4CHN C 6H 4)Br} n] ( 4a) and [{ Pd(C 6H 4CHN C 6H 4)Br} n] ( 5a) were formed. The bridge-splitting reactions of halogeno-bridged complexes were studied with different ligands like triphenylphosphine, triethylphosphite, 4-picoline, diethyldithiocarbamate and N-(2-hydroxy)benzylideneamine. All the double cyclopalladated complexes obtained were analysed by means of 1H NMR and 13C NMR spectroscopy.