Synthesis, characterization and catalytic properties of novel palladium(II) complexes containing aromatic sulfonamides: effective catalysts for the oxidation of benzyl alcohol

In this article, N-(2-aminophenyl)arylsulfonamides (1-5) were successfully synthesized by the reaction of o-phenylenediamine and various benzenesulfonyl chlorides. The Schiff base derivatives (1a-f; 4e) of those compounds were obtained using different aldehydes. Then, a series of neutral-four coordinate Pd(II) complexes (6-10) were prepared from the reaction of Pd(OAc)(2) and 1-5. On the other hand, when we tried to synthesize Pd(II) complexes containing Schiff base/sulfonamide ligands, two different situations were observed. Generally, when an electron-donating group was attached to the imine fragment (1a-d) except for 1f, the Schiff base hydrolyzed and 6 was isolated. When an electron-withdrawing group was attached to the imine fragment (1e, 4e), neutral four-coordinate Pd(II) complexes (11-13) bearing Schiff base/sulfonamide ligands were isolated. The synthesized compounds were characterized by FT-IR, elemental analysis and NMR spectroscopy. The complexes were used as a catalyst in the oxidation reaction of benzyl alcohol to benzaldehyde in the presence of H5IO6 in acetonitrile. All complexes showed satisfactory catalytic activity. The highest catalytic activity was obtained with 9. Copyright (C) 2012 John Wiley & Sons, Ltd.