Synthesis of palladium N-heterocyclic carbene complexes and investigation of catalytic activities in C-C bond formation reactions

N-heterocyclic carbenes (NHC) and their transition metal complexes have been recognized as being extraordinary versatile ligands for the organometallic chemistry and homogeneous catalysts. NHC complexes are used as catalysts in many organic reactions such as cross-coupling, C-C bond formation reactions, C-H activation reactions, hydroformylation, hydrogen transfer reactions and metathesis. The NHC complexes can exhibit high catalytic activity and selectivity in catalytic reactions due to high termal and moisture stability of M-NHC bond than analogues M-P bond. Thus, in this thesis, ditopic NHC benzimidazolium carbene precursors and their bimetallic Pd-PEPPSI complexes were synthesized and the catalytic activities of bimetallic Pd-PEPPSI complexes were investigated in Suzuki-Miyaura, Mizoroki-Heck and Sonogashira-Hagihara C-C bond formation reaction. The results can be summarized in three headings; 1) Ditopic NHC benzimidazolium carbene precursors (2a-i) were synthesized and their structures were illuminated by appropriate spectroscopic methods. 2) The bimetallic Pd-PEPPSI complexes (3a-g) of ditopic NHC benzimidazolium carbene precursors were synthesised by heating appropriate amount of PdCl2 and K2CO3 in pyridine and their structures were illuminated by appropriate spectroscopic methods. 3) The catalytic activities of synthesized bimatallic Pd-NHC-PEPPSI complexes (3a-g) were examined in Suzuki-Miyaura, Heck and Sonogashira C-C bond formation reactions. KEYWORDS: N-Heterocyclic carbene, ditopic carbene precursors, C-C bond formation, palladium-PEPPSI carbene complexes.