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 H 5 IO 6 in acetonitrile. All complexes showed satisfactory catalytic activity . The highest catalytic activity was obtained with 9. Copyright © 2012 John Wiley & Sons, Ltd.