S-donor functionalized N-heterocyclic carbene precursors and carbene complexes

In recent years, studies on the coordination chemistry of N-heterocyclic carbene (NHC) ligands have increased significantly. Studies have shown that NHC ligands, capable of forming highly stable bonds with a variety of main group and transition metals, represent an effective alternative to tertiary phosphines. The distinctive electronic properties of NHCs, such as high σ-donor and low π-acceptor, allow them to be readily converted into transition metal complexes. While NHCs with nitrogen, oxygen, or phosphorus donors are relatively common, those with sulfur donors are still relatively understudied. The sulfur atom exhibits different oxidation states ranging from 2- to 6+, enriching the already versatile NHC chemistry. The development of sulfur therapeutics is a key component of the pharmaceutical industry. Sulfur-derived functional groups are found in drugs and natural products. To date, it continues to be the predominant heteroatom integrated into 362 FDA-approved sulfur-containing drugs (in addition to oxygen or nitrogen). Sulfonamides, thioethers, sulfones, and penicillin are sulfur-containing structures that have been well studied in recent years, both in terms of synthesis and application. For the reasons mentioned above, in this thesis, three types of organosulfur (4-methylsulfonylbenzyl, 2-(phenylsulfonyl)ethyl, and 2-(phenylsulfide)ethyl)-functionalized benzimidazole-based NHC precursors (2, 8, 13), NHC-Pd(II)-pyridine (3, 9, 14), NHC-Ag(I) (4), NHC-Ru(II) (5), NHC=Se (6, 10), and NHC=S (11) complexes were synthesized and their structures were elucidated using appropriate spectroscopic methods (NMR and FT-IR). The enzyme inhibition activities of the synthesized benzimidazolium salts and the anticancer activities of NHC-Ag, NHC-Ru, and NHC=Se complexes were investigated.