Investigation of synthesis, characterization and catalytic activities of schiff base li̇gands and transition metal complexes

Our aim in this study is to synthesis and characterize original Schiff bases and their CoII, NiII, RuII‐p‐cymene and PdII metal complexes and to examine the catalytic activities of RuII‐p‐cymene and PdII complexes. In this study, after the synthesis of ethyl 2-amino-5,5,7,7-tetramethyl-4,5,6,7-tetrahydrothieno [2,3-c]pyridine-3-carboxylate starting material, Schiff bases were obtained as a result of the reaction with 2-hydroxybenzaldehyde and 2-hydroxy-3-methoxybenzaldehyde. Schiff base metal complexes were prepared using NiCl2∙6H2O, CoCl2∙6H2O, PdCl2(CH3CN)2 and [RuCl2(p-cymene)]2 compounds. The structures of Schiff bases and their metal complexes were elucidated using elemental analysis, magnetic susceptibility, 1H-NMR, 13C-NMR, FT-IR, UV-Vis, LC-MS, thermogravimetric analysis techniques. Octahedral structures for the obtained CoII, NiII and RuII‐p‐cymene complexes and square plane for PdII complexes have been proposed. The catalytic activities of the RuII‐p‐cemene complexes obtained after the characterization processes in the hydrogen transfer reactions were investigated by using acetophenone derivatives. Finally, synthesized PdII complexes were tested in the Suzuki-Miyaura and Mizoroki-Heck coupling reactions as catalyst. The product conversions obtained as a result of catalytic studies were determined using GC-MS. When 4-bromoacetophenone was used as a substrate in the hydrogen transfer reactions, catalysts 1 and 2 showed good catalytic activity of 93% and 96%. In addition, it was determined that palladium complexes showed moderate and good acttalytic activity for Suzuki-Miyaura and Mizoroki-Heck C-C coupling reactions.